78 changed files with 988 additions and 1461 deletions
--- a/.clang-format
+++ b/.clang-format
@ -1,38 +1,27 @@
---
 Language:        Cpp
 # BasedOnStyle:  LLVM
-AccessModifierOffset: -4
+AccessModifierOffset: -2
 AlignAfterOpenBracket: Align
-AlignArrayOfStructures: None
-AlignConsecutiveMacros: None
-AlignConsecutiveAssignments: None
-AlignConsecutiveBitFields: None
-AlignConsecutiveDeclarations: None
+AlignConsecutiveAssignments: false
+AlignConsecutiveDeclarations: false
 AlignEscapedNewlines: Right
-AlignOperands:   Align
+AlignOperands:   true
 AlignTrailingComments: true
-AllowAllArgumentsOnNextLine: true
-AllowAllConstructorInitializersOnNextLine: true
 AllowAllParametersOfDeclarationOnNextLine: true
-AllowShortEnumsOnASingleLine: true
-AllowShortBlocksOnASingleLine: Never
+AllowShortBlocksOnASingleLine: false
 AllowShortCaseLabelsOnASingleLine: false
 AllowShortFunctionsOnASingleLine: All
-AllowShortLambdasOnASingleLine: All
-AllowShortIfStatementsOnASingleLine: Never
+AllowShortIfStatementsOnASingleLine: false
 AllowShortLoopsOnASingleLine: false
 AlwaysBreakAfterDefinitionReturnType: None
 AlwaysBreakAfterReturnType: None
 AlwaysBreakBeforeMultilineStrings: false
-AlwaysBreakTemplateDeclarations: MultiLine
-AttributeMacros:
-  - __capability
+AlwaysBreakTemplateDeclarations: false
 BinPackArguments: true
 BinPackParameters: true
 BraceWrapping:   
-  AfterCaseLabel:  false
-  AfterClass:      false
-  AfterControlStatement: Never
+  AfterClass:      true
+  AfterControlStatement: false
  AfterEnum:       false
  AfterFunction:   false
  AfterNamespace:  false
@ -42,21 +31,13 @@ BraceWrapping:
  AfterExternBlock: false
  BeforeCatch:     false
  BeforeElse:      false
-  BeforeLambdaBody: false
-  BeforeWhile:     false
  IndentBraces:    false
  SplitEmptyFunction: true
  SplitEmptyRecord: true
  SplitEmptyNamespace: true
 BreakBeforeBinaryOperators: None
-BreakBeforeConceptDeclarations: true
-BreakBeforeBraces: Custom
-BraceWrapping:
-  AfterClass: true
-  AfterFunction: true
-  AfterNamespace: true
+BreakBeforeBraces: Linux
 BreakBeforeInheritanceComma: false
-BreakInheritanceList: BeforeColon
 BreakBeforeTernaryOperators: true
 BreakConstructorInitializersBeforeComma: false
 BreakConstructorInitializers: BeforeColon
@ -69,56 +50,35 @@ ConstructorInitializerAllOnOneLineOrOnePerLine: false
 ConstructorInitializerIndentWidth: 4
 ContinuationIndentWidth: 4
 Cpp11BracedListStyle: true
-DeriveLineEnding: true
 DerivePointerAlignment: false
 DisableFormat:   false
-EmptyLineAfterAccessModifier: Never
-EmptyLineBeforeAccessModifier: LogicalBlock
 ExperimentalAutoDetectBinPacking: false
 FixNamespaceComments: true
 ForEachMacros:   
  - foreach
  - Q_FOREACH
  - BOOST_FOREACH
-IfMacros:
-  - KJ_IF_MAYBE
 IncludeBlocks:   Preserve
 IncludeCategories: 
  - Regex:           '^"(llvm|llvm-c|clang|clang-c)/'
    Priority:        2
-    SortPriority:    0
-    CaseSensitive:   false
  - Regex:           '^(<|"(gtest|gmock|isl|json)/)'
    Priority:        3
-    SortPriority:    0
-    CaseSensitive:   false
  - Regex:           '.*'
    Priority:        1
-    SortPriority:    0
-    CaseSensitive:   false
 IncludeIsMainRegex: '(Test)?$'
-IncludeIsMainSourceRegex: ''
-IndentAccessModifiers: false
 IndentCaseLabels: false
-IndentCaseBlocks: false
-IndentGotoLabels: true
 IndentPPDirectives: None
-IndentExternBlock: AfterExternBlock
-IndentRequires:  false
 IndentWidth:     4
 IndentWrappedFunctionNames: false
-InsertTrailingCommas: None
 JavaScriptQuotes: Leave
 JavaScriptWrapImports: true
 KeepEmptyLinesAtTheStartOfBlocks: true
-LambdaBodyIndentation: Signature
 MacroBlockBegin: ''
 MacroBlockEnd:   ''
 MaxEmptyLinesToKeep: 1
 NamespaceIndentation: None
-ObjCBinPackProtocolList: Auto
 ObjCBlockIndentWidth: 2
-ObjCBreakBeforeNestedBlockParam: true
 ObjCSpaceAfterProperty: false
 ObjCSpaceBeforeProtocolList: true
 PenaltyBreakAssignment: 2
@ -126,57 +86,24 @@ PenaltyBreakBeforeFirstCallParameter: 19
 PenaltyBreakComment: 300
 PenaltyBreakFirstLessLess: 120
 PenaltyBreakString: 1000
-PenaltyBreakTemplateDeclaration: 10
 PenaltyExcessCharacter: 1000000
 PenaltyReturnTypeOnItsOwnLine: 60
-PenaltyIndentedWhitespace: 0
-PointerAlignment: Right
-PPIndentWidth:   -1
-ReferenceAlignment: Pointer
+PointerAlignment: Left
 ReflowComments:  true
-ShortNamespaceLines: 1
-SortIncludes:    CaseSensitive
-SortJavaStaticImport: Before
+SortIncludes:    true
 SortUsingDeclarations: true
 SpaceAfterCStyleCast: false
-SpaceAfterLogicalNot: false
 SpaceAfterTemplateKeyword: true
 SpaceBeforeAssignmentOperators: true
-SpaceBeforeCaseColon: false
-SpaceBeforeCpp11BracedList: false
-SpaceBeforeCtorInitializerColon: true
-SpaceBeforeInheritanceColon: true
 SpaceBeforeParens: ControlStatements
-SpaceAroundPointerQualifiers: Default
-SpaceBeforeRangeBasedForLoopColon: true
-SpaceInEmptyBlock: false
 SpaceInEmptyParentheses: false
 SpacesBeforeTrailingComments: 1
-SpacesInAngles:  Never
-SpacesInConditionalStatement: false
+SpacesInAngles:  false
 SpacesInContainerLiterals: true
 SpacesInCStyleCastParentheses: false
-SpacesInLineCommentPrefix:
-  Minimum:         1
-  Maximum:         -1
 SpacesInParentheses: false
 SpacesInSquareBrackets: false
-SpaceBeforeSquareBrackets: false
-BitFieldColonSpacing: Both
-Standard:        Latest
-StatementAttributeLikeMacros:
-  - Q_EMIT
-StatementMacros:
-  - Q_UNUSED
-  - QT_REQUIRE_VERSION
+Standard:        Auto
 TabWidth:        8
-UseCRLF:         false
 UseTab:          Never
-WhitespaceSensitiveMacros:
-  - STRINGIZE
-  - PP_STRINGIZE
-  - BOOST_PP_STRINGIZE
-  - NS_SWIFT_NAME
-  - CF_SWIFT_NAME
-...

--- a/.gitignore
+++ b/.gitignore
@ -1,4 +1 @@
 build
-.vscode/ipch/*
-.kdev4
-.cache
--- a/.gitmodules
+++ b/.gitmodules
@ -1,6 +1,3 @@
-[submodule "subprojects/nlohmann_json"]
-	path = subprojects/nlohmann_json
+[submodule "3rdparty/nlohmann_json"]
+	path = 3rdparty/nlohmann_json
 	url = https://github.com/nlohmann/json.git
-[submodule "subprojects/singleapplication"]
-	path = subprojects/singleapplication/singleapplication.git
-	url = https://github.com/itay-grudev/SingleApplication.git
--- a/.vscode/launch.json
+++ b/.vscode/launch.json
@ -21,8 +21,7 @@
                    "text": "-enable-pretty-printing",
                    "ignoreFailures": true
                }
-            ],
-            "visualizerFile": "/home/brodbemn/.config/Code - OSS/User/workspaceStorage/d64ec049841ecb3d43e402bb3c167cb5/tonka3000.qtvsctools/qt.natvis.xml"
+            ]
        }
    ]
 }
--- a/.vscode/settings.json
+++ b/.vscode/settings.json
@ -65,47 +65,9 @@
        "condition_variable": "cpp",
        "mutex": "cpp",
        "hash_map": "cpp",
-        "future": "cpp",
-        "bit": "cpp",
-        "compare": "cpp",
-        "concepts": "cpp",
-        "forward_list": "cpp",
-        "map": "cpp",
-        "set": "cpp",
-        "string": "cpp",
-        "unordered_set": "cpp",
-        "iterator": "cpp",
-        "memory_resource": "cpp",
-        "random": "cpp",
-        "semaphore": "cpp",
-        "stop_token": "cpp",
-        "__bit_reference": "cpp",
-        "__bits": "cpp",
-        "__config": "cpp",
-        "__debug": "cpp",
-        "__errc": "cpp",
-        "__hash_table": "cpp",
-        "__locale": "cpp",
-        "__mutex_base": "cpp",
-        "__node_handle": "cpp",
-        "__split_buffer": "cpp",
-        "__threading_support": "cpp",
-        "__tree": "cpp",
-        "__tuple": "cpp",
-        "__verbose_abort": "cpp",
-        "format": "cpp",
-        "ios": "cpp",
-        "locale": "cpp"
+        "future": "cpp"
    },
    "C_Cpp.clang_format_path": "/usr/bin/clang-format",
    "cmake.configureOnOpen": true,
-    "C_Cpp.configurationWarnings": "Disabled",
-    "files.watcherExclude": {
-        "**/.git/objects/**": true,
-        "**/.git/subtree-cache/**": true,
-        "**/node_modules/*/**": true,
-        "**/.hg/store/**": true,
-        ".flatpak/**": true,
-        "_build/**": true
-    }
+    "C_Cpp.configurationWarnings": "Disabled"
 }
--- a/subprojects/CMakeLists.txt
+++ b/subprojects/CMakeLists.txt
@ -2,4 +2,3 @@ if(NOT KIMA2_USE_EXTERNAL_JSON)
  set(JSON_BuildTests OFF CACHE INTERNAL "")
  add_subdirectory(nlohmann_json EXCLUDE_FROM_ALL)
 endif()
-#add_subdirectory(csv-parser)
--- a/3rdparty/nlohmann_json
+++ b/3rdparty/nlohmann_json
@ -0,0 +1 @@
+Subproject commit f1768a540a7b7c5cc30cdcd6be9e9ef91083719b
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@ -1,10 +1,10 @@
-cmake_minimum_required(VERSION 3.10)
+cmake_minimum_required(VERSION 3.8)

-project(kima2 VERSION 1.8.3)
+project(kima2 VERSION 0.13.1)

-set(CMAKE_MODULE_PATH "${CMAKE_HOME_DIRECTORY}/cmake")
+set(CMAKE_MODULE_PATH "${CMAKE_HOME_DIRECTORY}/cmake" ${CMAKE_MODULE_PATH})

-set(CMAKE_CXX_STANDARD 20)
+set(CMAKE_CXX_STANDARD 17)
 set(CMAKE_CXX_STANDARD_REQUIRED ON)

 #include(InstallRequiredSystemLibraries)
@ -12,12 +12,10 @@ set(CMAKE_CXX_STANDARD_REQUIRED ON)
 if(MSVC)
  add_compile_options(/W4 /WX)
 else()
-  #add_compile_options(-Wall -Wextra -pedantic -Woverloaded-virtual -Wredundant-decls -Wshadow)
-  add_compile_options(-Wall -Wextra)
+  add_compile_options(-Wall -Wextra -pedantic -Woverloaded-virtual -Wredundant-decls -Wshadow)
 endif()

 configure_file(config.h.in ${PROJECT_BINARY_DIR}/config.h)
-configure_file(de.rustysoft.kima2.metainfo.xml.in ${PROJECT_BINARY_DIR}/de.rustysoft.kima2.metainfo.xml)

 set(CMAKE_RUNTIME_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR}/bin)
 set(CMAKE_LIBRARY_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR}/lib)
@ -29,14 +27,14 @@ if(KIMA2_USE_EXTERNAL_JSON)
  find_package(nlohmann_json REQUIRED)
 endif()

-add_subdirectory(subprojects)
+add_subdirectory(3rdparty)
 add_subdirectory(src)

-#if(NOT CMAKE_BUILD_TYPE OR CMAKE_BUILD_TYPE MATCHES Debug)
-#  include(CTest)
-#  enable_testing()
-#  add_subdirectory(test)
-#endif()
+if(NOT CMAKE_BUILD_TYPE OR CMAKE_BUILD_TYPE MATCHES Debug)
+  include(CTest)
+  enable_testing()
+  add_subdirectory(test)
+endif()


 # CPack
@ -80,8 +78,6 @@ else(WIN32 AND NOT UNIX)
 	  DESTINATION share/${PROJECT_NAME})
  install(FILES "${CMAKE_SOURCE_DIR}/misc/kima2.svg"
        DESTINATION share/icons/hicolor/scalable/apps)
-  install(FILES de.rustysoft.kima2.metainfo.xml
-	  DESTINATION share/metainfo)
 endif (WIN32 AND NOT UNIX)

 if( MINGW )
@ -90,19 +86,18 @@ if( MINGW )
    set( CMAKE_INSTALL_SYSTEM_RUNTIME_LIBS
    ${MINGW_PATH}/libstdc++-6.dll
    ${MINGW_PATH}/libgcc_s_seh-1.dll
-    ${MINGW_PATH}/Qt6Core.dll
-    ${MINGW_PATH}/Qt6Gui.dll
-    ${MINGW_PATH}/Qt6Widgets.dll
-    ${MINGW_PATH}/Qt6PrintSupport.dll
-    ${MINGW_PATH}/Qt6Network.dll
+    ${MINGW_PATH}/Qt5Core.dll
+    ${MINGW_PATH}/Qt5Gui.dll
+    ${MINGW_PATH}/Qt5Widgets.dll
+    ${MINGW_PATH}/Qt5PrintSupport.dll
    ${MINGW_PATH}/libwinpthread-1.dll
    ${MINGW_PATH}/libsqlite3-0.dll
    ${MINGW_PATH}/libusb-1.0.dll
-    ${MINGW_PATH}/libicuuc75.dll
-    ${MINGW_PATH}/libicuin75.dll
-    ${MINGW_PATH}/libicudt75.dll
+    ${MINGW_PATH}/libxlnt.dll
+    ${MINGW_PATH}/libicuuc62.dll
+    ${MINGW_PATH}/libicuin62.dll
+    ${MINGW_PATH}/libicudt62.dll
    ${MINGW_PATH}/libpcre2-16-0.dll
-    ${MINGW_PATH}/libpcre2-8-0.dll
    ${MINGW_PATH}/zlib1.dll
    ${MINGW_PATH}/libharfbuzz-0.dll
    ${MINGW_PATH}/libpng16-16.dll
@ -112,26 +107,20 @@ if( MINGW )
    ${MINGW_PATH}/libbz2-1.dll
    ${MINGW_PATH}/libintl-8.dll
    ${MINGW_PATH}/libpcre-1.dll
-    ${MINGW_PATH}/libdouble-conversion.dll
-    ${MINGW_PATH}/libzstd.dll
-    ${MINGW_PATH}/libmd4c.dll
-    ${MINGW_PATH}/libbrotlicommon.dll
-    ${MINGW_PATH}/libbrotlidec.dll
-    #${MINGW_PATH}/libfmt.dll
-    ${MINGW_PATH}/libb2-1.dll
    ${MINGW_PATH}/libiconv-2.dll)
-    install(FILES ${MINGW_PATH}/../share/qt6/plugins/platforms/qwindows.dll
-      ${MINGW_PATH}/../share/qt6/plugins/platforms/qminimal.dll
+    install(FILES ${MINGW_PATH}/../share/qt5/plugins/platforms/qwindows.dll
+      ${MINGW_PATH}/../share/qt5/plugins/platforms/qminimal.dll
      DESTINATION bin/platforms)
-    #install(FILES ${MINGW_PATH}/../share/qt6/plugins/printsupport/windowsprintersupport.dll
-    #  DESTINATION bin/printsupport)
-    install(FILES ${MINGW_PATH}/../share/qt6/translations/qtbase_de.qm
-      ${MINGW_PATH}/../share/qt6/translations/qt_de.qm
-      ${MINGW_PATH}/../share/qt6/translations/qt_help_de.qm
-      ${MINGW_PATH}/../share/qt6/translations/qtmultimedia_de.qm
-      DESTINATION bin/share/qt6/translations)
-    install(FILES ${MINGW_PATH}/../share/qt6/plugins/styles/qmodernwindowsstyle.dll
-      DESTINATION bin/styles)
+    install(FILES ${MINGW_PATH}/../share/qt5/plugins/printsupport/windowsprintersupport.dll
+      DESTINATION bin/printsupport)
+    install(FILES ${MINGW_PATH}/../share/qt5/translations/qtbase_de.qm
+      ${MINGW_PATH}/../share/qt5/translations/qt_de.qm
+      ${MINGW_PATH}/../share/qt5/translations/qt_help_de.qm
+      ${MINGW_PATH}/../share/qt5/translations/qtmultimedia_de.qm
+      ${MINGW_PATH}/../share/qt5/translations/qtquick1_de.qm
+      ${MINGW_PATH}/../share/qt5/translations/qtscript_de.qm
+      ${MINGW_PATH}/../share/qt5/translations/qtxmlpatterns_de.qm
+      DESTINATION bin/translations)
 endif( MINGW )

 include(InstallRequiredSystemLibraries)
--- a/2
+++ b/2
@ -1,4 +1,4 @@
-Copyright © 2018-2024 Martin Brodbeck
+Copyright © 2018 Martin Brodbeck

 Hiermit wird unentgeltlich jeder Person, die eine Kopie der Software und der
 zugehörigen Dokumentationen (die "Software") erhält, die Erlaubnis erteilt,
--- a/README.md
+++ b/README.md
@ -13,16 +13,19 @@ Verkaufsdaten nach dem Verkaufsende auszutauschen.
 Ebenso können über einen ESC/POS-Drucker Quittungen ausgestellt werden.

 ## Installation
-Auf [rustysoft.de](https://www.rustysoft.de/software/kima2/) werden die Installationsmöglichkeiten (Flatpak, Windows-Installer) erläutert. Bitte die Hinweise dort beachten.
+Auf [rustysoft.de](https://www.rustysoft.de/?01_kima2) werden verschiedene Installationspakete (Arch Linux,
+Ubuntu, Windows) angeboten. Bitte die Hinweise dort beachten.

-## Selbst compilieren
+### Selbst compilieren
 KIMA2 benötigt folgende Libraries:
-* Qt 6
-* boost >= 1.80
+* Qt5
+* boost >= 1.62
 * libusb-1.0
+* xlnt >= 1.3.0
 * nlohmann-json (als 3rdparty submodule vorhanden)

-Da Features aus C++20 sowie von neueren Compilern verwendet werden, sollte als Compiler mindestens GCC 14 verwendet werden.
+Da Features aus C++17 verwendet werden sowie std::filesystem, sollte als Compiler mindestens
+GCC 8 verwendet werden.

 Die Installationsschritte unter Linux sind wie folgt:
 ```
--- a/de.rustysoft.kima2.metainfo.xml.in
+++ b/de.rustysoft.kima2.metainfo.xml.in
@ -1,27 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<component type="desktop-application">
-  <id>de.rustysoft.kima2</id>
-  
-  <name>KIMA2</name>
-  <summary>A small cash point program for children’s stuff markets</summary>
-  
-  <metadata_license>MIT</metadata_license>
-  <project_license>GPL-3.0-or-later</project_license>
-
-  <releases>
-    <release version="@PROJECT_VERSION@" type="stable" date="2024-01-23" />
-  </releases>
-  
-  <description>
-    <p>
-      A small cash point program for children's stuff markets. German language only.
-    </p>
-  </description>
-  
-  <launchable type="desktop-id">de.rustysoft.kima2.desktop</launchable>
-  <screenshots>
-    <screenshot type="default">
-      <image>https://rustysoft.de/images/software/kima2/screenshot.png</image>
-    </screenshot>
-  </screenshots>
-</component>
--- a/kima2.kdev4
+++ b/kima2.kdev4
@ -1,4 +0,0 @@
-[Project]
-CreatedFrom=CMakeLists.txt
-Manager=KDevCMakeManager
-Name=kima2
--- a/manual/Benutzerhandbuch.odt
+++ b/manual/Benutzerhandbuch.odt
--- a/manual/Benutzerhandbuch.pdf
+++ b/manual/Benutzerhandbuch.pdf
--- a/meson.build
+++ b/meson.build
@ -1,33 +0,0 @@
-project('kima2', 'cpp', default_options : ['cpp_std=c++20'], version : '1.8.0')
-
-conf_data = configuration_data()
-conf_data.set('PROJECT_VERSION', '"' + meson.project_version() + '"')
-configure_file(output : 'config.h',
-               configuration : conf_data)
-configuration_inc = include_directories('.')
-               
-#csv = cmake.subproject('csv-parser')
-#csv_lib = csv.dependency('csv')
-
-nlohmann_lib = dependency('nlohmann_json', version : '>=3.5.0', required : false)
-
-if not nlohmann_lib.found()
-  nlohmann_inc = include_directories('subprojects/nlohmann_json/single_include')
-  nlohmann_lib = declare_dependency(include_directories : nlohmann_inc)
-endif
-
-csv_inc = include_directories('subprojects/csv-parser/single_include')
-csv_dep = declare_dependency(include_directories : csv_inc)
-
-singleapp_proj = subproject('singleapplication')
-singleapp_lib = singleapp_proj.get_variable('singleapp_lib')
-singleapp_dep = singleapp_proj.get_variable('singleapp_dep')
-
-subdir('src')
-
-if build_machine.system() == 'linux'
-  install_data('misc/kima2.svg', install_dir : get_option('datadir') / 'icons/hicolor/scalable/apps')
-  install_data('misc/kima2.desktop', install_dir : get_option('datadir') / 'applications')
-  install_data('manual/Benutzerhandbuch.pdf', install_dir : get_option('datadir') / 'kima2')
-endif
-
--- a/misc/PKGBUILD
+++ b/misc/PKGBUILD
@ -1,35 +1,29 @@
 # Maintainer: Martin Brodbeck <martin at brodbeck-online dot de>
 pkgname=kima2
-pkgver=1.7.1
+pkgver=0.13.0
 pkgrel=1
 pkgdesc="A small cash point program for children's things markets (German only)"
 arch=('i686' 'x86_64')
-url="http://www.rustysoft.de/software/kima2"
+url="http://www.rustysoft.de/?01_kima2"
 license=('custom')
-depends=('glibc' 'libusb' 'qt6-base' 'sqlite3')
+depends=('glibc' 'libusb' 'qt5-base' 'sqlite3' 'xlnt')
 makedepends=('boost>=1.62')
-source=(git+https://git.rustysoft.de/martin/kima2)
-sha256sums=('SKIP')
+source=($pkgname-$pkgver.tar.gz)
+md5sums=('')

 build() {
-  cd $pkgname
-
-  git checkout v$pkgver
-  git submodule init
-  git submodule update
-
-  if [ -d build ]; then
-    rm -rf build
+  if [ ! -d $pkgname/build ]; then
+    mkdir $pkgname/build
  fi
-  mkdir build && cd build
+  cd $pkgname/build

-  cmake -DCMAKE_BUILD_TYPE=Release -DCMAKE_INSTALL_PREFIX=/usr -DKIMA2_USE_EXTERNAL_JSON=OFF ..
+  cmake -DCMAKE_BUILD_TYPE=Release -DCMAKE_INSTALL_PREFIX=$pkgdir/usr -DKIMA2_USE_EXTERNAL_JSON=ON ..
  make
 }

 package() {
  cd $pkgname/build
-  make DESTDIR="$pkgdir" install
+  make install
  cd ..
  install -D -m644 LICENSE "${pkgdir}/usr/share/licenses/${pkgname}/LICENSE"
 }
--- a/misc/kima2.desktop
+++ b/misc/kima2.desktop
@ -3,8 +3,8 @@ Type=Application
 Name=KIMA2
 GenericName=Cash Point Program
 GenericName[de]=Kassenprogramm
-Comment=A small cash point program for children's stuff markets
-Comment[de]=Ein kleines Kassenprogramm für Kindersachenmärkte
+Comment=A small cash point program
+Comment[de]=Ein kleines Kassenprogramm
 Exec=kima2
 Icon=kima2
 Categories=Office;
--- a/misc/kima2.spec
+++ b/misc/kima2.spec
@ -1,43 +0,0 @@
-Name: kima2
-Version: 1.6.0
-Release: 1%{?dist}
-Summary: A small cash point program for children's things markets
-License: custom
-
-Source0: %{name}-%{version}.tar.gz
-
-BuildRequires: meson
-BuildRequires: gcc-c++
-#BuildRequires: pkgconfig(nlohmann_json)
-BuildRequires: boost-date-time
-BuildRequires: sqlite-devel
-BuildRequires: libusb-devel
-BuildRequires: qt5-qtdeclarative-devel
-#BuildRequires: pkgconfig(pthreads)
-
-%description
-
-%prep
-%autosetup
-
-%build
-%meson
-%meson_build
-
-%install
-%meson_install
-
-%check
-%meson_test
-
-%files
-%{_bindir}/kima2
-%{_datadir}/applications/kima2.desktop
-%{_datadir}/icons/hicolor/scalable/apps/kima2.svg
-%{_datadir}/kima2/Benutzerhandbuch.pdf
-
-
-%changelog
-* Fri Oct 11 2019 Martin Brodbeck <infor@rustysoft.de> - dev builds
- 
-
--- a/src/core/CMakeLists.txt
+++ b/src/core/CMakeLists.txt
@ -1,34 +1,34 @@
 set(Boost_USE_STATIC_LIBS ON)

-find_package(Boost 1.78 REQUIRED)
+find_package(Boost 1.62 COMPONENTS date_time REQUIRED)
 find_package(SQLite3 REQUIRED)

-# Because csv-parser needs threads:
-
-find_package(fmt)
+if (MINGW)
+  find_package(XLNT REQUIRED STATIC)
+else (MINGW)
+  find_package(PkgConfig REQUIRED)
+  pkg_check_modules(XLNT REQUIRED xlnt>=1.3)
+endif (MINGW)

 set(CORE_SOURCES
    database.cpp
    entity.cpp
-    entityint.cpp
-    entityuuid.cpp
    seller.cpp
    article.cpp
    sale.cpp
    marketplace.cpp
-    csvreader.cpp
+    excelreader.cpp
    jsonutil.cpp
    utils.cpp
 )

-
 add_library(core STATIC ${CORE_SOURCES})
-#target_include_directories(core PRIVATE ${PROJECT_SOURCE_DIR}/subprojects/csv-parser/single_include)
+
 if (WIN32)
-    target_link_libraries(core PRIVATE sqlite3 nlohmann_json::nlohmann_json)
+    target_link_libraries(core PRIVATE printer Boost::boost Boost::date_time sqlite3 nlohmann_json::nlohmann_json ${XLNT_LIBRARY})
    target_link_libraries(core PRIVATE bcrypt)
 else()
-	target_link_libraries(core PRIVATE sqlite3 nlohmann_json::nlohmann_json)
+	target_link_libraries(core PRIVATE printer Boost::boost Boost::date_time sqlite3 nlohmann_json::nlohmann_json ${XLNT_LIBRARIES})
 endif()

-target_include_directories(core PUBLIC ${CMAKE_CURRENT_SOURCE_DIR}/..)
+target_include_directories(core PUBLIC ${CMAKE_CURRENT_SOURCE_DIR})
--- a/src/core/article.cpp
+++ b/src/core/article.cpp
@ -1,38 +1,44 @@
 #include "article.h"
-#include "seller.h"
 #include "utils.h"

 #include <iomanip>
 #include <sstream>

-Article::Article(int price) : m_price(price) {}
+// Article::Article() : Entity() {}

-void Article::setArticleNo(int articleNo) { m_articleNo = articleNo; }
+Article::Article(int price) : price_(price) {}

-void Article::setPrice(int price) { m_price = price; }
+// Article::Article(std::shared_ptr<Seller> sellerPtr) : Entity() { sellerPtr_ = sellerPtr; }

-void Article::setDescription(const std::string &description) { m_description = description; }
+void Article::setArticleNo(int articleNo) { articleNo_ = articleNo; }

-void Article::setSale(Sale *salePtr) { m_salePtr = salePtr; }
+void Article::setPrice(int price) { price_ = price; }

-void Article::setSeller(Seller *sellerPtr) { m_sellerPtr = sellerPtr; }
+void Article::setDescription(const std::string& description) { description_ = description; }

-bool Article::isSold() { return m_salePtr ? true : false; }
+void Article::setSale(Sale* salePtr) { salePtr_ = salePtr; }

-std::string Article::getDescription() { return m_description; }
+void Article::setSeller(Seller* sellerPtr) { sellerPtr_ = sellerPtr; }

-Seller *Article::getSeller() { return m_sellerPtr; }
-Sale *Article::getSale() { return m_salePtr; }
+bool Article::isSold() { return salePtr_ ? true : false; }

-int Article::getPrice() const { return m_price; }
+std::string Article::getDescription() { return description_; }

-std::string Article::getPriceAsString() const { return formatCentAsEuroString(m_price); }
+Seller* Article::getSeller() { return sellerPtr_; }
+Sale* Article::getSale() { return salePtr_; }

-int Article::getArticleNo() const { return m_articleNo; }
+int Article::getPrice() const { return price_; }
+
+std::string Article::getPriceAsString() const
+{
+    return formatCentAsEuroString(price_);
+}
+
+int Article::getArticleNo() const { return articleNo_; }

 std::string Article::getCompleteArticleNo() const
 {
    std::stringstream artNoStream;
-    artNoStream << m_sourceNo << "K" << std::setfill('0') << std::setw(5) << m_articleNo;
+    artNoStream << sourceNo_ << "K" << std::setfill('0') << std::setw(5) << articleNo_;
    return artNoStream.str();
 }
--- a/src/core/article.h
+++ b/src/core/article.h
@ -1,7 +1,9 @@
 #ifndef ARTICLE_H
 #define ARTICLE_H

-#include "entityuuid.h"
+#include "entity.h"
+//#include "sale.h"
+//#include "seller.h"

 #include <memory>
 #include <string>
@ -9,35 +11,34 @@
 class Seller;
 class Sale;

-class Article : public EntityUuid
+class Article : public Entity
 {
-public:
+  public:
    Article() = default;
    Article(int price);
-    Article(const Article &) = delete;
-    virtual ~Article() = default;
+    //virtual ~Article() = default;

    void setArticleNo(int articleNo);
    void setPrice(int price);
-    void setDescription(const std::string &description);
+    void setDescription(const std::string& description);
    bool isSold();
-    void setSale(Sale *salePtr);
-    void setSeller(Seller *sellerPtr);
+    void setSale(Sale* salePtr);
+    void setSeller(Seller* sellerPtr);

    int getArticleNo() const;
    std::string getCompleteArticleNo() const;
    std::string getDescription();
-    Seller *getSeller();
-    Sale *getSale();
+    Seller* getSeller();
+    Sale* getSale();
    int getPrice() const;
    std::string getPriceAsString() const;

-private:
-    Seller *m_sellerPtr{};
-    Sale *m_salePtr{};
-    int m_articleNo{};
-    int m_price{};
-    std::string m_description{};
+  private:
+    Seller* sellerPtr_{};
+    Sale* salePtr_{};
+    int articleNo_{};
+    int price_{};
+    std::string description_{};
 };

 #endif
--- a/src/core/csvreader.cpp
+++ b/src/core/csvreader.cpp
@ -1,92 +0,0 @@
-#include "csvreader.h"
-#include "utils.h"
-
-#include <fstream>
-
-// #include <csv.hpp>
-#include <boost/algorithm/string.hpp>
-
-#ifdef DELETE
-#undef DELETE
-#endif
-
-namespace fs = std::filesystem;
-
-std::size_t CsvReader::readSellersFromFile(const fs::path &filePath, Marketplace *market)
-{
-
-#if defined(_WIN64) || defined(_WIN32)
-    // Windows: Somhow this is necessary in order to open file names with umlauts
-    auto wide = filePath.wstring();
-    std::string fileName(wide.begin(), wide.end());
-
-    std::ifstream infile(fileName);
-#else
-    // csv::CSVReader csvReader(filePath.string(), format);
-    std::ifstream infile(filePath.string());
-#endif
-
-    for (auto &seller : market->getSellers()) {
-        seller->setState(Seller::State::DELETE);
-    }
-
-    market->storeToDb(true);
-
-    std::string line;
-
-    while (getline(infile, line)) {
-        std::vector<std::string> strs;
-        boost::split(strs, line, boost::is_any_of(";"));
-
-        auto seller = std::make_unique<Seller>();
-
-        try {
-            int sellerNo = std::stoi(strs[0]);
-            seller->setSellerNo(sellerNo);
-        } catch (std::invalid_argument const &ex) {
-            continue;
-        }
-
-        if (isNumber(strs[1]))
-            seller->setNumArticlesOffered(std::stoi(strs[1]));
-        else
-            seller->setNumArticlesOffered(0);
-
-        // If both, first name and last name, are empty, use N. N.
-        // Else, use the real values.
-        if (strs[2].empty() && strs[2].empty()) {
-            seller->setFirstName("N.");
-            seller->setLastName("N.");
-        } else {
-            std::string firstName = strs[2];
-            seller->setFirstName(trim(firstName));
-            std::string lastName = strs[3];
-            seller->setLastName(trim(lastName));
-        }
-
-        market->getSellers().push_back(std::move(seller));
-    }
-
-    // Add one additional seller "RESERVE RESERVE"
-    auto seller = std::make_unique<Seller>();
-    seller->setSellerNo(market->getNextSellerNo());
-    seller->setFirstName("RESERVE");
-    seller->setLastName("RESERVE");
-    market->getSellers().push_back(std::move(seller));
-
-    // If there was no special seller "Sonderkonto" in import data, then create one
-    auto specialSeller = market->findSellerWithSellerNo(0);
-    if (!specialSeller) {
-        auto seller = std::make_unique<Seller>();
-        seller->setSellerNo(0);
-        seller->setLastName("Sonderkonto");
-        seller->setFirstName("Sonderkonto");
-        seller->setNumArticlesOffered(0);
-        market->getSellers().push_back(std::move(seller));
-    }
-
-    market->sortSellers();
-    market->storeToDb();
-
-    return market->getSellers().size() - 1; // minus 1 because we don't count the "special" seller
-}
--- a/src/core/csvreader.h
+++ b/src/core/csvreader.h
@ -1,19 +0,0 @@
-#ifndef CSV_READER_H
-#define CSV_READER_H
-
-#include "marketplace.h"
-#include "seller.h"
-
-#include <filesystem>
-#include <memory>
-#include <string>
-#include <vector>
-
-class CsvReader
-{
-public:
-    static std::size_t readSellersFromFile(const std::filesystem::path &filePath,
-                                           Marketplace *market);
-};
-
-#endif
--- a/src/core/database.cpp
+++ b/src/core/database.cpp
@ -1,13 +1,13 @@
 #include "database.h"

-#include <chrono>
 #include <filesystem>
-#include <format>
 #include <iostream>
 #include <stdexcept>
 #include <vector>

-Database::Database(const std::string &dbname)
+#include "boost/date_time/posix_time/posix_time.hpp"
+
+Database::Database(const std::string& dbname)
 {
    dbname_ = dbname;
    init();
@ -28,7 +28,7 @@ Database::Database()
    if (!fs::exists(dbpath)) {
        try {
            fs::create_directories(dbpath);
-        } catch (fs::filesystem_error &err) {
+        } catch (fs::filesystem_error& err) {
            throw err;
        }
    }
@ -45,11 +45,8 @@ void Database::newDb()

    fs::path sourcePath = dbname_;
    fs::path destPath = sourcePath.parent_path() / sourcePath.stem();
-
-    auto chronoTime = std::chrono::system_clock::now();
-    std::string timeString = std::format("{0:%FT%H-%M-%S}", chronoTime);
-
-    destPath += std::string("_") += timeString += ".db";
+    destPath += std::string("_") +=
+        boost::posix_time::to_iso_string(boost::posix_time::second_clock::local_time()) += ".db";

    fs::copy_file(sourcePath, destPath, fs::copy_options::overwrite_existing);

@ -60,13 +57,13 @@ void Database::newDb()

 Database::~Database() { sqlite3_close(db_); }

-void Database::exec(const std::string &sql)
+void Database::exec(const std::string& sql)
 {
-    char *errMsg;
+    char* errMsg;
    const int errCode = sqlite3_exec(db_, sql.c_str(), nullptr, nullptr, &errMsg);
    if (errCode) {
        std::string errMsgString(errMsg); // Make a C++ string of the errMsg, so that we can call
-                                            // sqlite3_free() before throwing the exception
+                                          // sqlite3_free() before throwing the exception
        sqlite3_free(errMsg);
        throw std::runtime_error("Error in SQL execution: " + errMsgString);
    }
@ -78,10 +75,11 @@ void Database::createNew()

    std::string sqlCreateKima2{"CREATE TABLE IF NOT EXISTS kima2 ("
                               "version INTEGER NOT NULL);"
-                               "INSERT INTO kima2 (version) VALUES (3);"};
+                               "INSERT INTO kima2 (version) VALUES (2);"};
    sqlStrings.push_back(sqlCreateKima2);
    std::string sqlCreateSellers{"CREATE TABLE IF NOT EXISTS sellers ("
-                                 "seller_no INTEGER PRIMARY KEY NOT NULL, "
+                                 "id TEXT PRIMARY KEY NOT NULL, "
+                                 "seller_no INTEGER, "
                                 "first_name TEXT, "
                                 "last_name TEXT, "
                                 "num_offered_articles INTEGER, "
@ -91,13 +89,13 @@ void Database::createNew()
    std::string sqlCreateArticles{
        "CREATE TABLE IF NOT EXISTS articles ("
        "id TEXT PRIMARY KEY NOT NULL, "
-        "seller_no TEXT NOT NULL, "
+        "seller_id TEXT NOT NULL, "
        "source_no INTEGER NOT NULL, "
        "article_no INTEGER NOT NULL, "
        "description TEXT, "
        "price INTEGER NOT NULL, "
        "UNIQUE (source_no, article_no), "
-        "FOREIGN KEY (seller_no) REFERENCES sellers(seller_no) ON DELETE CASCADE, "
+        "FOREIGN KEY (seller_id) REFERENCES sellers(id) ON DELETE CASCADE, "
        "CHECK (article_no BETWEEN 0 AND 99999)"
        ");"};
    sqlStrings.push_back(sqlCreateArticles);
@ -117,13 +115,13 @@ void Database::createNew()
    sqlStrings.push_back(sqlCreateSalesItems);

    std::string sqlInitialEntries{
-        "INSERT OR IGNORE INTO sellers (seller_no, first_name, last_name, "
+        "INSERT OR IGNORE INTO sellers (id, seller_no, first_name, last_name, "
        "num_offered_articles) VALUES "
-        "(0, 'Sonderkonto', 'Sonderkonto', 0)"};
+        "('11111111-1111-1111-1111-111111111111', 0, 'Sonderkonto', 'Sonderkonto', 0)"};
    sqlStrings.push_back(sqlInitialEntries);

    beginTransaction();
-    for (const auto &sql : sqlStrings) {
+    for (const auto& sql : sqlStrings) {
        exec(sql);
    }
    endTransaction();
@ -132,15 +130,13 @@ void Database::createNew()
 void Database::updateDbToVer2()
 {
    beginTransaction();
-    exec("INSERT OR IGNORE INTO sellers (seller_no, first_name, last_name, "
+    exec("INSERT OR IGNORE INTO sellers (id, seller_no, first_name, last_name, "
         "num_offered_articles) VALUES "
-         "(0, 'Sonderkonto', 'Sonderkonto', 0)");
-    exec("UPDATE kima2 SET version = 3");
+         "('11111111-1111-1111-1111-111111111111', 0, 'Sonderkonto', 'Sonderkonto', 0)");
+    exec("UPDATE kima2 SET version = 2");
    endTransaction();
 }

-void Database::updateDbToVer3() { newDb(); }
-
 void Database::init()
 {
    const int errCode = sqlite3_open(dbname_.c_str(), &db_);
@ -156,19 +152,12 @@ void Database::init()
    switch (version) {
    case 0:
        createNew();
-        initResult_ = InitResult::OK;
        break;
    case 1:
-        updateDbToVer3();
-        initResult_ = InitResult::OUTDATED_REPLACED;
-        break;
-    case 2:
-        updateDbToVer3();
-        initResult_ = InitResult::OUTDATED_REPLACED;
+        updateDbToVer2();
        break;
    default:
        // Do nothing because we are up-to-date.
-        initResult_ = InitResult::OK;
        break;
    }
 }
@ -176,7 +165,7 @@ void Database::init()
 int Database::getVersion()
 {
    int retCode{};
-    sqlite3_stmt *stmt;
+    sqlite3_stmt* stmt;

    // Check if there's already a kima2 table available.
    // If not, return version == 0.
@ -223,26 +212,29 @@ void Database::beginTransaction() { exec("BEGIN TRANSACTION"); }

 void Database::endTransaction() { exec("END TRANSACTION"); }

-unsigned int Database::storeSellers(std::vector<std::unique_ptr<Seller>> &sellers, bool onlyDelete)
+unsigned int Database::storeSellers(std::vector<std::unique_ptr<Seller>>& sellers, bool onlyDelete)
 {
    int retCode{};
    int count{};
-    sqlite3_stmt *stmt;
+    sqlite3_stmt* stmt;

    beginTransaction();

-    for (auto &seller : sellers) {
+    for (auto& seller : sellers) {
        if (seller->getState() == Seller::State::NEW && !onlyDelete) {
            retCode = sqlite3_prepare_v2(
                db_,
                "INSERT INTO sellers"
-                " (seller_no, first_name, last_name, num_offered_articles)"
-                " VALUES (:seller_no, :first_name, :last_name, :num_offered_articles)",
+                " (id, seller_no, first_name, last_name, num_offered_articles)"
+                " VALUES (:uuid, :seller_no, :first_name, :last_name, :num_offered_articles)",
                -1, &stmt, nullptr);

            if (retCode != SQLITE_OK)
                throw std::runtime_error(sqlite3_errmsg(db_));

+            sqlite3_bind_text(stmt, sqlite3_bind_parameter_index(stmt, ":uuid"),
+                              boost::uuids::to_string(seller->getUuid()).c_str(), -1,
+                              SQLITE_TRANSIENT);
            sqlite3_bind_int(stmt, sqlite3_bind_parameter_index(stmt, ":seller_no"),
                             seller->getSellerNo());
            sqlite3_bind_text(stmt, sqlite3_bind_parameter_index(stmt, ":first_name"),
@ -268,13 +260,15 @@ unsigned int Database::storeSellers(std::vector<std::unique_ptr<Seller>> &seller
                "UPDATE sellers SET"
                " seller_no = :seller_no, first_name = :first_name,"
                " last_name = :last_name, num_offered_articles = :num_offered_articles"
-                " WHERE seller_no = :id",
+                " WHERE id = :uuid",
                -1, &stmt, nullptr);

            if (retCode != SQLITE_OK)
                throw std::runtime_error(sqlite3_errmsg(db_));

-            sqlite3_bind_int(stmt, sqlite3_bind_parameter_index(stmt, ":id"), seller->getId());
+            sqlite3_bind_text(stmt, sqlite3_bind_parameter_index(stmt, ":uuid"),
+                              boost::uuids::to_string(seller->getUuid()).c_str(), -1,
+                              SQLITE_TRANSIENT);
            sqlite3_bind_int(stmt, sqlite3_bind_parameter_index(stmt, ":seller_no"),
                             seller->getSellerNo());
            sqlite3_bind_text(stmt, sqlite3_bind_parameter_index(stmt, ":first_name"),
@ -297,13 +291,15 @@ unsigned int Database::storeSellers(std::vector<std::unique_ptr<Seller>> &seller
        } else if (seller->getState() == Seller::State::DELETE) {
            count += static_cast<int>(seller->getArticles(false).size());

-            retCode = sqlite3_prepare_v2(db_, "DELETE FROM sellers WHERE seller_no = :id", -1,
-                                         &stmt, nullptr);
+            retCode =
+                sqlite3_prepare_v2(db_, "DELETE FROM sellers WHERE id = :uuid", -1, &stmt, nullptr);

            if (retCode != SQLITE_OK)
                throw std::runtime_error(sqlite3_errmsg(db_));

-            sqlite3_bind_int(stmt, sqlite3_bind_parameter_index(stmt, ":id"), seller->getId());
+            sqlite3_bind_text(stmt, sqlite3_bind_parameter_index(stmt, ":uuid"),
+                              boost::uuids::to_string(seller->getUuid()).c_str(), -1,
+                              SQLITE_TRANSIENT);

            retCode = sqlite3_step(stmt);

@ -326,12 +322,12 @@ unsigned int Database::storeSellers(std::vector<std::unique_ptr<Seller>> &seller

    // Everything went fine, so we can now update our objects
    sellers.erase(std::remove_if(sellers.begin(), sellers.end(),
-                                 [](const std::unique_ptr<Seller> &seller) {
+                                 [](const std::unique_ptr<Seller>& seller) {
                                     return (seller->getState() == Seller::State::DELETE);
                                 }),
                  sellers.end());

-    for (auto &seller : sellers) {
+    for (auto& seller : sellers) {
        seller->cleanupArticles();
        seller->setState(Seller::State::OK);
    }
@ -339,18 +335,18 @@ unsigned int Database::storeSellers(std::vector<std::unique_ptr<Seller>> &seller
    return count;
 }

-unsigned int Database::storeArticles(std::vector<Article *> articles)
+unsigned int Database::storeArticles(std::vector<Article*> articles)
 {
    int retCode{};
    int count{};
-    sqlite3_stmt *stmt;
+    sqlite3_stmt* stmt;

-    for (auto &article : articles) {
+    for (auto& article : articles) {
        if (article->getState() == Article::State::NEW) {
            retCode = sqlite3_prepare_v2(
                db_,
                "INSERT INTO articles"
-                " (id, seller_no, source_no, article_no, description, price)"
+                " (id, seller_id, source_no, article_no, description, price)"
                " VALUES (:uuid, :seller_id, :source_no, :article_no, :desc, :price)",
                -1, &stmt, nullptr);

@ -360,8 +356,9 @@ unsigned int Database::storeArticles(std::vector<Article *> articles)
            sqlite3_bind_text(stmt, sqlite3_bind_parameter_index(stmt, ":uuid"),
                              boost::uuids::to_string(article->getUuid()).c_str(), -1,
                              SQLITE_TRANSIENT);
-            sqlite3_bind_int(stmt, sqlite3_bind_parameter_index(stmt, ":seller_id"),
-                             article->getSeller()->getId());
+            sqlite3_bind_text(stmt, sqlite3_bind_parameter_index(stmt, ":seller_id"),
+                              boost::uuids::to_string(article->getSeller()->getUuid()).c_str(), -1,
+                              SQLITE_TRANSIENT);
            sqlite3_bind_int(stmt, sqlite3_bind_parameter_index(stmt, ":source_no"),
                             article->getSourceNo());
            sqlite3_bind_int(stmt, sqlite3_bind_parameter_index(stmt, ":article_no"),
@ -385,7 +382,7 @@ unsigned int Database::storeArticles(std::vector<Article *> articles)
            retCode = sqlite3_prepare_v2(
                db_,
                "UPDATE articles SET"
-                " seller_no = :seller_id, source_no = :source_no, article_no = :article_no,"
+                " seller_id = seller_id, source_no = :source_no, article_no = :article_no,"
                " description = :desc, price = :price"
                " WHERE id = :uuid",
                -1, &stmt, nullptr);
@ -396,8 +393,9 @@ unsigned int Database::storeArticles(std::vector<Article *> articles)
            sqlite3_bind_text(stmt, sqlite3_bind_parameter_index(stmt, ":uuid"),
                              boost::uuids::to_string(article->getUuid()).c_str(), -1,
                              SQLITE_TRANSIENT);
-            sqlite3_bind_int(stmt, sqlite3_bind_parameter_index(stmt, ":seller_id"),
-                             article->getSeller()->getId());
+            sqlite3_bind_text(stmt, sqlite3_bind_parameter_index(stmt, ":seller_id"),
+                              boost::uuids::to_string(article->getSeller()->getUuid()).c_str(), -1,
+                              SQLITE_TRANSIENT);
            sqlite3_bind_int(stmt, sqlite3_bind_parameter_index(stmt, ":source_no"),
                             article->getSourceNo());
            sqlite3_bind_int(stmt, sqlite3_bind_parameter_index(stmt, ":article_no"),
@ -444,18 +442,18 @@ unsigned int Database::storeArticles(std::vector<Article *> articles)
    return count;
 }

-unsigned int Database::storeSales(std::vector<std::unique_ptr<Sale>> &sales)
+unsigned int Database::storeSales(std::vector<std::unique_ptr<Sale>>& sales)
 {
    int retCode{};
    int count{};
-    sqlite3_stmt *stmt;
+    sqlite3_stmt* stmt;

    if (sales.size() == 0)
        return 0;

    beginTransaction();

-    for (auto &sale : sales) {
+    for (auto& sale : sales) {
        if (sale->getState() == Sale::State::NEW) {
            retCode = sqlite3_prepare_v2(db_,
                                         "INSERT INTO sales"
@ -485,7 +483,7 @@ unsigned int Database::storeSales(std::vector<std::unique_ptr<Sale>> &sales)
            ++count;
            sqlite3_finalize(stmt);

-            for (const auto &article : sale->getArticles()) {
+            for (const auto& article : sale->getArticles()) {
                retCode = sqlite3_prepare_v2(db_,
                                             "INSERT INTO sales_items"
                                             " (sale_id, article_id)"
@ -538,24 +536,24 @@ unsigned int Database::storeSales(std::vector<std::unique_ptr<Sale>> &sales)
    // Everything went fine, so we can now update our objects
    sales.erase(
        std::remove_if(sales.begin(), sales.end(),
-                       [](const auto &sale) { return (sale->getState() == Sale::State::DELETE); }),
+                       [](const auto& sale) { return (sale->getState() == Sale::State::DELETE); }),
        sales.end());

-    for (auto &sale : sales) {
+    for (auto& sale : sales) {
        sale->setState(Sale::State::OK);
    }

    return count;
 }

-unsigned int Database::loadSellers(std::vector<std::unique_ptr<Seller>> &sellers)
+unsigned int Database::loadSellers(std::vector<std::unique_ptr<Seller>>& sellers)
 {
    int retCode{};
    int count{};
-    sqlite3_stmt *stmt;
+    sqlite3_stmt* stmt;

    retCode = sqlite3_prepare_v2(db_,
-                                 "SELECT seller_no, first_name, last_name, "
+                                 "SELECT id, seller_no, first_name, last_name, "
                                 "num_offered_articles FROM sellers ORDER BY seller_no",
                                 -1, &stmt, nullptr);
    if (retCode != SQLITE_OK)
@ -568,10 +566,11 @@ unsigned int Database::loadSellers(std::vector<std::unique_ptr<Seller>> &sellers
    while (retCode != SQLITE_DONE) {
        ++count;
        auto seller = std::make_unique<Seller>();
-        seller->setSellerNo(sqlite3_column_int(stmt, 0));
-        seller->setFirstName(reinterpret_cast<const char *>(sqlite3_column_text(stmt, 1)));
-        seller->setLastName(reinterpret_cast<const char *>(sqlite3_column_text(stmt, 2)));
-        seller->setNumArticlesOffered(sqlite3_column_int(stmt, 3));
+        seller->setUuidFromString(reinterpret_cast<const char*>(sqlite3_column_text(stmt, 0)));
+        seller->setSellerNo(sqlite3_column_int(stmt, 1));
+        seller->setFirstName(reinterpret_cast<const char*>(sqlite3_column_text(stmt, 2)));
+        seller->setLastName(reinterpret_cast<const char*>(sqlite3_column_text(stmt, 3)));
+        seller->setNumArticlesOffered(sqlite3_column_int(stmt, 4));
        seller->setState(Seller::State::OK);
        sellers.push_back(std::move(seller));

@ -580,29 +579,29 @@ unsigned int Database::loadSellers(std::vector<std::unique_ptr<Seller>> &sellers

    sqlite3_finalize(stmt);

-    for (auto &seller : sellers) {
+    for (auto& seller : sellers) {
        retCode = sqlite3_prepare_v2(db_,
                                     "SELECT id, source_no, article_no, description, price"
                                     " FROM articles"
-                                     " WHERE seller_no = :seller_id"
+                                     " WHERE seller_id = :seller_uuid"
                                     " ORDER BY article_no",
                                     -1, &stmt, nullptr);
        if (retCode != SQLITE_OK)
            throw std::runtime_error(sqlite3_errmsg(db_));

-        sqlite3_bind_int(stmt, sqlite3_bind_parameter_index(stmt, ":seller_id"), seller->getId());
+        sqlite3_bind_text(stmt, sqlite3_bind_parameter_index(stmt, ":seller_uuid"),
+                          boost::uuids::to_string(seller->getUuid()).c_str(), -1, SQLITE_TRANSIENT);

        retCode = sqlite3_step(stmt);

        while (retCode != SQLITE_DONE) {
            ++count;
            auto article = std::make_unique<Article>();
-            article->setUuidFromString(
-                reinterpret_cast<const char *>(sqlite3_column_text(stmt, 0)));
+            article->setUuidFromString(reinterpret_cast<const char*>(sqlite3_column_text(stmt, 0)));
            article->setSeller(seller.get());
            article->setSourceNo(sqlite3_column_int(stmt, 1));
            article->setArticleNo(sqlite3_column_int(stmt, 2));
-            article->setDescription(reinterpret_cast<const char *>(sqlite3_column_text(stmt, 3)));
+            article->setDescription(reinterpret_cast<const char*>(sqlite3_column_text(stmt, 3)));
            article->setPrice(sqlite3_column_int(stmt, 4));
            article->setState(Article::State::OK);

@ -617,12 +616,12 @@ unsigned int Database::loadSellers(std::vector<std::unique_ptr<Seller>> &sellers
    return count;
 }

-unsigned int Database::loadSales(std::vector<std::unique_ptr<Sale>> &sales,
-                                 std::vector<std::unique_ptr<Seller>> &sellers)
+unsigned int Database::loadSales(std::vector<std::unique_ptr<Sale>>& sales,
+                                 std::vector<std::unique_ptr<Seller>>& sellers)
 {
    int retCode{};
    int count{};
-    sqlite3_stmt *stmt;
+    sqlite3_stmt* stmt;

    retCode = sqlite3_prepare_v2(db_,
                                 "SELECT id, source_no, sold_at"
@ -635,13 +634,13 @@ unsigned int Database::loadSales(std::vector<std::unique_ptr<Sale>> &sales,

    sales.clear();

-    std::map<std::string, Sale *> saleMap;
+    std::map<std::string, Sale*> saleMap;
    while (retCode != SQLITE_DONE) {
        ++count;
        auto sale = std::make_unique<Sale>();
-        sale->setUuidFromString(reinterpret_cast<const char *>(sqlite3_column_text(stmt, 0)));
+        sale->setUuidFromString(reinterpret_cast<const char*>(sqlite3_column_text(stmt, 0)));
        sale->setSourceNo(sqlite3_column_int(stmt, 1));
-        sale->setTimestamp(reinterpret_cast<const char *>(sqlite3_column_text(stmt, 2)));
+        sale->setTimestamp(reinterpret_cast<const char*>(sqlite3_column_text(stmt, 2)));
        sale->setState(Sale::State::OK);
        saleMap.insert(std::make_pair(sale->getUuidAsString(), sale.get()));
        sales.push_back(std::move(sale));
@ -651,8 +650,8 @@ unsigned int Database::loadSales(std::vector<std::unique_ptr<Sale>> &sales,

    sqlite3_finalize(stmt);

-    std::map<std::string, Article *> artMap;
-    for (const auto &seller : sellers) {
+    std::map<std::string, Article*> artMap;
+    for (const auto& seller : sellers) {
        for (const auto article : seller->getArticles(false)) {
            artMap.insert(std::make_pair(article->getUuidAsString(), article));
        }
@ -668,8 +667,8 @@ unsigned int Database::loadSales(std::vector<std::unique_ptr<Sale>> &sales,
    retCode = sqlite3_step(stmt);

    while (retCode != SQLITE_DONE) {
-        saleMap[reinterpret_cast<const char *>(sqlite3_column_text(stmt, 0))]->addArticle(
-            artMap[reinterpret_cast<const char *>(sqlite3_column_text(stmt, 1))]);
+        saleMap[reinterpret_cast<const char*>(sqlite3_column_text(stmt, 0))]->addArticle(
+            artMap[reinterpret_cast<const char*>(sqlite3_column_text(stmt, 1))]);

        retCode = sqlite3_step(stmt);
    }
@ -682,7 +681,7 @@ unsigned int Database::loadSales(std::vector<std::unique_ptr<Sale>> &sales,
 void Database::updateCashPointNo(int oldCashPointNo, int newCashPointNo)
 {
    int retCode{};
-    sqlite3_stmt *stmt;
+    sqlite3_stmt* stmt;

    // Check if the new no ist already in use
    retCode = sqlite3_prepare_v2(db_, "SELECT COUNT() FROM articles WHERE source_no = :source_no",
--- a/src/core/database.h
+++ b/src/core/database.h
@ -10,36 +10,32 @@

 class Database
 {
-public:
-    enum class InitResult { OK, OUTDATED_REPLACED };
-    explicit Database(const std::string &dbname);
+  public:
+    explicit Database(const std::string& dbname);
    Database();
    ~Database();
-    Database(const Database &) = delete;
-    Database &operator=(const Database &) = delete;
-    void exec(const std::string &sql);
-    unsigned int storeSellers(std::vector<std::unique_ptr<Seller>> &sellers,
+    Database(const Database&) = delete;
+    Database& operator=(const Database&) = delete;
+    void exec(const std::string& sql);
+    unsigned int storeSellers(std::vector<std::unique_ptr<Seller>>& sellers,
                              bool onlyDelete = false);
-    unsigned int loadSellers(std::vector<std::unique_ptr<Seller>> &sellers);
-    unsigned int storeSales(std::vector<std::unique_ptr<Sale>> &sales);
-    unsigned int loadSales(std::vector<std::unique_ptr<Sale>> &sales,
-                           std::vector<std::unique_ptr<Seller>> &sellers);
+    unsigned int loadSellers(std::vector<std::unique_ptr<Seller>>& sellers);
+    unsigned int storeSales(std::vector<std::unique_ptr<Sale>>& sales);
+    unsigned int loadSales(std::vector<std::unique_ptr<Sale>>& sales,
+                           std::vector<std::unique_ptr<Seller>>& sellers);
    void updateCashPointNo(int oldCashPointNo, int newCashPointNo);
    void newDb();
-    InitResult getInitResult() { return initResult_; }

-private:
-    sqlite3 *db_{nullptr};
+  private:
+    sqlite3* db_{nullptr};
    std::string dbname_;
    void init();
    void beginTransaction();
    void endTransaction();
    void createNew();
    int getVersion();
-    unsigned int storeArticles(std::vector<Article *> articles);
+    unsigned int storeArticles(std::vector<Article*> articles);
    void updateDbToVer2();
-    void updateDbToVer3();
-    InitResult initResult_{InitResult::OK};
 };

 #endif // DATABASE_H
--- a/src/core/entity.cpp
+++ b/src/core/entity.cpp
@ -1,3 +1,33 @@
 #include "entity.h"

-Entity::State Entity::getState() const { return m_state; }
+#include <iostream>
+
+#include <boost/uuid/uuid_generators.hpp>
+#include <boost/uuid/uuid_io.hpp>
+
+Entity::~Entity() = default;
+
+void Entity::createUuid()
+{
+    static boost::uuids::random_generator generator{};
+    uuid_ = generator();
+}
+
+void Entity::setUuidFromString(const std::string& uuidString)
+{
+    boost::uuids::string_generator generator{};
+    uuid_ = generator(uuidString);
+}
+
+Entity::State Entity::getState() const
+{
+    return state_;
+}
+
+void Entity::setSourceNo(int sourceNo) {
+    sourceNo_ = sourceNo;
+}
+
+int Entity::getSourceNo() const {
+    return sourceNo_;
+}
--- a/src/core/entity.h
+++ b/src/core/entity.h
@ -1,16 +1,35 @@
 #ifndef ENTITY_H
 #define ENTITY_H

+#include <string>
+
+#include <boost/uuid/uuid.hpp>
+#include <boost/uuid/uuid_io.hpp>
+
 class Entity
 {
-public:
+  public:
    enum class State { NEW, UPDATE, DELETE, OK };
-    virtual ~Entity() = default;
-    void setState(State state) { m_state = state; }
-    virtual State getState() const;

-private:
-    State m_state{State::NEW};
+    // Entity() = default;
+    virtual ~Entity() = 0;
+
+    void createUuid();
+    void setUuidFromString(const std::string& uuidString);
+    void setState(State state) { state_ = state; }
+    void setSourceNo(int sourceNo);
+
+    const boost::uuids::uuid& getUuid() const { return uuid_; };
+    std::string getUuidAsString() const { return boost::uuids::to_string(uuid_); }
+    virtual State getState() const;
+    virtual int getSourceNo() const;
+
+  protected:
+    int sourceNo_{};
+
+  private:
+    boost::uuids::uuid uuid_{};
+    State state_{State::NEW};
 };

 #endif // ENTITY_H
--- a/src/core/entityint.cpp
+++ b/src/core/entityint.cpp
@ -1,5 +0,0 @@
-#include "entityint.h"
-
-EntityInt::EntityInt(int id) { m_id = id; }
-
-void EntityInt::setId(int id) { m_id = id; }
--- a/src/core/entityint.h
+++ b/src/core/entityint.h
@ -1,19 +0,0 @@
-#ifndef ENTITY_INT_H
-#define ENTITY_INT_H
-
-#include "entity.h"
-
-class EntityInt : public Entity
-{
-public:
-    EntityInt() = default;
-    virtual ~EntityInt() = default;
-    EntityInt(int id);
-    void setId(int id);
-    int getId() const { return m_id; };
-
-protected:
-    int m_id{};
-};
-
-#endif // ENTITY_INT_H
--- a/src/core/entityuuid.cpp
+++ b/src/core/entityuuid.cpp
@ -1,22 +0,0 @@
-#include "entityuuid.h"
-
-#include <iostream>
-
-#include <boost/uuid/uuid_generators.hpp>
-#include <boost/uuid/uuid_io.hpp>
-
-void EntityUuid::createUuid()
-{
-    static boost::uuids::random_generator generator{};
-    m_uuid = generator();
-}
-
-void EntityUuid::setUuidFromString(const std::string &uuidString)
-{
-    boost::uuids::string_generator generator{};
-    m_uuid = generator(uuidString);
-}
-
-void EntityUuid::setSourceNo(int sourceNo) { m_sourceNo = sourceNo; }
-
-int EntityUuid::getSourceNo() const { return m_sourceNo; }
--- a/src/core/entityuuid.h
+++ b/src/core/entityuuid.h
@ -1,32 +0,0 @@
-#ifndef ENTITY_UUID_H
-#define ENTITY_UUID_H
-
-#include "entity.h"
-
-#include <string>
-
-#include <boost/uuid/uuid.hpp>
-#include <boost/uuid/uuid_io.hpp>
-
-class EntityUuid : public Entity
-{
-public:
-    EntityUuid() = default;
-    virtual ~EntityUuid() = default;
-
-    void createUuid();
-    void setUuidFromString(const std::string &uuidString);
-    void setSourceNo(int sourceNo);
-
-    const boost::uuids::uuid &getUuid() const { return m_uuid; };
-    std::string getUuidAsString() const { return boost::uuids::to_string(m_uuid); }
-    virtual int getSourceNo() const;
-
-protected:
-    int m_sourceNo{};
-
-private:
-    boost::uuids::uuid m_uuid{};
-};
-
-#endif // ENTITY_UUID_H
--- a/src/core/excelreader.cpp
+++ b/src/core/excelreader.cpp
@ -0,0 +1,63 @@
+#include "excelreader.h"
+
+#include <xlnt/xlnt.hpp>
+#include <fstream>
+
+namespace fs = std::filesystem;
+
+void ExcelReader::readSellersFromFile(const fs::path& filePath, Marketplace* market)
+{
+    xlnt::workbook wb;
+    std::ifstream mystream(filePath, std::ios::binary);
+    if(!mystream.is_open()) {
+	throw std::runtime_error("Could not open ecxel file");
+    }
+    wb.load(mystream);
+
+    for (auto& seller : market->getSellers()) {
+        seller->setState(Seller::State::DELETE);
+    }
+
+    market->storeToDb(true);
+    auto ws = wb.sheet_by_index(0);
+
+    const int START_ROW = 5;
+    const int END_ROW = 350;
+
+    int rowCount{};
+    for (const auto& row : ws.rows(false)) {
+        if (rowCount < START_ROW) {
+            ++rowCount;
+            continue;
+        } else if (rowCount > END_ROW) {
+            break;
+        }
+        if (row[2].value<std::string>().empty() && row[3].value<std::string>().empty()) {
+            ++rowCount;
+            continue;
+        }
+        auto seller = std::make_unique<Seller>();
+        seller->createUuid();
+        seller->setSellerNo(row[0].value<int>());
+        seller->setNumArticlesOffered(row[1].value<int>());
+        seller->setFirstName(row[2].value<std::string>());
+        seller->setLastName(row[3].value<std::string>());
+        market->getSellers().push_back(std::move(seller));
+        rowCount++;
+    }
+
+    // If there was no special seller "Sonderkonto" in import data, then create one
+    auto specialSeller = market->findSellerWithUuid("11111111-1111-1111-1111-111111111111");
+    if (!specialSeller) {
+        auto seller = std::make_unique<Seller>();
+        seller->setUuidFromString("11111111-1111-1111-1111-111111111111");
+        seller->setSellerNo(0);
+        seller->setLastName("Sonderkonto");
+        seller->setFirstName("Sonderkonto");
+        seller->setNumArticlesOffered(0);
+        market->getSellers().push_back(std::move(seller));
+    }
+
+    market->sortSellers();
+    market->storeToDb();
+}
--- a/src/core/excelreader.h
+++ b/src/core/excelreader.h
@ -0,0 +1,18 @@
+#ifndef EXCEL_READER_H
+#define EXCEL_READER_H
+
+#include "marketplace.h"
+#include "seller.h"
+
+#include <filesystem>
+#include <memory>
+#include <string>
+#include <vector>
+
+class ExcelReader
+{
+  public:
+    static void readSellersFromFile(const std::filesystem::path& filePath, Marketplace* market);
+};
+
+#endif
--- a/src/core/jsonutil.cpp
+++ b/src/core/jsonutil.cpp
@ -5,15 +5,17 @@

 #include <fstream>

+namespace fs = std::filesystem;
 using json = nlohmann::json;

-void JsonUtil::exportSellers(const std::filesystem::path &filePath, Marketplace *market)
+void JsonUtil::exportSellers(const std::filesystem::path& filePath, Marketplace* market)
 {
    json root;
    std::ofstream file(filePath);

-    for (const auto &seller : market->getSellers()) {
+    for (const auto& seller : market->getSellers()) {
        json newEntry;
+        newEntry["uuid"] = seller->getUuidAsString();
        newEntry["seller_no"] = seller->getSellerNo();
        newEntry["last_name"] = seller->getLastName();
        newEntry["first_name"] = seller->getFirstName();
@ -24,9 +26,9 @@ void JsonUtil::exportSellers(const std::filesystem::path &filePath, Marketplace
    file << root.dump(4) << std::endl;
 }

-std::size_t JsonUtil::importSellers(const std::filesystem::path &filePath, Marketplace *market)
+void JsonUtil::importSellers(const std::filesystem::path& filePath, Marketplace* market)
 {
-    for (auto &seller : market->getSellers()) {
+    for (auto& seller : market->getSellers()) {
        seller->setState(Seller::State::DELETE);
    }
    market->storeToDb(true);
@ -36,6 +38,7 @@ std::size_t JsonUtil::importSellers(const std::filesystem::path &filePath, Marke

    for (auto val : jsonValues["sellers"]) {
        auto seller = std::make_unique<Seller>();
+        seller->setUuidFromString(val["uuid"]);
        seller->setSellerNo(val["seller_no"]);
        seller->setLastName(val["last_name"]);
        seller->setFirstName(val["first_name"]);
@ -44,9 +47,10 @@ std::size_t JsonUtil::importSellers(const std::filesystem::path &filePath, Marke
    }

    // If there was no special seller "Sonderkonto" in import data, then create one
-    auto specialSeller = market->findSellerWithSellerNo(0);
+    auto specialSeller = market->findSellerWithUuid("11111111-1111-1111-1111-111111111111");
    if (!specialSeller) {
        auto seller = std::make_unique<Seller>();
+        seller->setUuidFromString("11111111-1111-1111-1111-111111111111");
        seller->setSellerNo(0);
        seller->setLastName("Sonderkonto");
        seller->setFirstName("Sonderkonto");
@ -55,20 +59,18 @@ std::size_t JsonUtil::importSellers(const std::filesystem::path &filePath, Marke
    }

    market->sortSellers();
-    market->storeToDb();

-    return market->getSellers().size() - 1; // minus 1 because we don't count the "special" seller
+    market->storeToDb();
 }

-void JsonUtil::exportSales(const std::filesystem::path &filePath, Marketplace *market,
-                           int cashPointNo)
+void JsonUtil::exportSales(const std::filesystem::path& filePath, Marketplace* market, int cashPointNo)
 {
    json root;
    std::ofstream file(filePath);

    root["source_no"] = cashPointNo;

-    for (const auto &sale : market->getSales()) {
+    for (const auto& sale : market->getSales()) {
        if (sale->getSourceNo() != cashPointNo)
            continue;

@ -76,10 +78,10 @@ void JsonUtil::exportSales(const std::filesystem::path &filePath, Marketplace *m
        newSale["uuid"] = sale->getUuidAsString();
        newSale["timestamp"] = sale->getTimestamp();

-        for (const auto &article : sale->getArticles()) {
+        for (const auto& article : sale->getArticles()) {
            json newArticle;
            newArticle["uuid"] = article->getUuidAsString();
-            newArticle["seller_no"] = article->getSeller()->getSellerNo();
+            newArticle["seller_uuid"] = article->getSeller()->getUuidAsString();
            newArticle["desc"] = article->getDescription();
            newArticle["price"] = article->getPrice();
            // newArticle["source_no"] = article->getSourceNo();
@ -94,36 +96,33 @@ void JsonUtil::exportSales(const std::filesystem::path &filePath, Marketplace *m
    file << root.dump(4) << std::endl;
 }

-void JsonUtil::importSales(const std::filesystem::path &filePath, Marketplace *market,
-                           int cashPointNo)
+void JsonUtil::importSales(const std::filesystem::path& filePath, Marketplace* market, int cashPointNo)
 {
    std::ifstream file(filePath);
    json jsonValues = json::parse(file);

    int source_no = jsonValues["source_no"];
    if (source_no == cashPointNo) {
-        std::string ret = "Die Kassen-Nr. ";
-        ret += std::to_string(source_no);
-        ret += " der zu imporierenden Daten wird von dieser Kasse hier bereits verwendet.";
-        throw std::runtime_error(ret);
+        throw std::runtime_error("Die Kassen-Nr. der zu imporierenden Daten wird von dieser Kasse "
+                                 "hier bereits verwendet.");
    }

    market->setSalesToDelete(jsonValues["source_no"]);
    market->storeToDb();

-    for (const auto &valSale : jsonValues["sales"]) {
+    for (const auto& valSale : jsonValues["sales"]) {
        auto sale = std::make_unique<Sale>();
        sale->setUuidFromString(valSale["uuid"]);
        sale->setSourceNo(jsonValues["source_no"]);
        sale->setTimestamp(valSale["timestamp"]);
-        for (const auto &valArticle : valSale["articles"]) {
+        for (const auto& valArticle : valSale["articles"]) {
            auto article = std::make_unique<Article>();
            article->setUuidFromString(valArticle["uuid"]);
            article->setSourceNo(jsonValues["source_no"]);
            article->setArticleNo(valArticle["article_no"]);
            article->setDescription(valArticle["desc"]);
            article->setPrice(valArticle["price"]);
-            auto seller = market->findSellerWithSellerNo(valArticle["seller_no"]);
+            auto seller = market->findSellerWithUuid(valArticle["seller_uuid"]);
            if (seller == nullptr) {
                throw std::runtime_error(
                    "Die zu importierenden Daten verweisen auf einen nicht vorhandenen Verkäufer. "
--- a/src/core/jsonutil.h
+++ b/src/core/jsonutil.h
@ -3,18 +3,16 @@

 #include "marketplace.h"

-#include <filesystem>
 #include <string>
+#include <filesystem>

 class JsonUtil
 {
-public:
-    static void exportSellers(const std::filesystem::path &filePath, Marketplace *market);
-    static std::size_t importSellers(const std::filesystem::path &filePath, Marketplace *market);
-    static void exportSales(const std::filesystem::path &filePath, Marketplace *market,
-                            int cashPointNo);
-    static void importSales(const std::filesystem::path &filePath, Marketplace *market,
-                            int cashPointNo);
+  public:
+    static void exportSellers(const std::filesystem::path& filePath, Marketplace* market);
+    static void importSellers(const std::filesystem::path& filePath, Marketplace* market);
+    static void exportSales(const std::filesystem::path& filePath, Marketplace* market, int cashPointNo);
+    static void importSales(const std::filesystem::path& filePath, Marketplace* market, int cashPointNo);
 };

 #endif
--- a/src/core/marketplace.cpp
+++ b/src/core/marketplace.cpp
@ -3,19 +3,19 @@
 #include "utils.h"

 #include <algorithm>
-#include <filesystem>
 #include <fstream>
 #include <iomanip>
 #include <numeric>
 #include <sstream>
+#include <filesystem>

 namespace fs = std::filesystem;

 Marketplace::Marketplace()
 {
-    /*auto seller = std::make_unique<Seller>("Max", "Mustermann");
+    auto seller = std::make_unique<Seller>("Max", "Mustermann");
    seller->createUuid();
-    sellers_.push_back(std::move(seller)); */
+    sellers_.push_back(std::move(seller));
 }

 void Marketplace::storeToDb(bool onlyDelete)
@ -25,23 +25,22 @@ void Marketplace::storeToDb(bool onlyDelete)
    db.storeSales(sales_);
 }

-Database::InitResult Marketplace::loadFromDb()
+void Marketplace::loadFromDb()
 {
    Database db;
    db.loadSellers(sellers_);
    db.loadSales(sales_, sellers_);
-    return db.getInitResult();
 }

-SellersVec &Marketplace::getSellers() { return sellers_; }
+SellersVec& Marketplace::getSellers() { return sellers_; }

-SalesVec &Marketplace::getSales() { return sales_; }
+SalesVec& Marketplace::getSales() { return sales_; }

 int Marketplace::getNextSellerNo()
 {
    auto iter = std::max_element(
        sellers_.begin(), sellers_.end(),
-        [](const auto &a, const auto &b) -> bool { return a->getSellerNo() < b->getSellerNo(); });
+        [](const auto& a, const auto& b) -> bool { return a->getSellerNo() < b->getSellerNo(); });
    if (iter == sellers_.end())
        return 1;
    return (*iter)->getSellerNo() + 1;
@ -53,14 +52,14 @@ int Marketplace::getNextArticleNo()
    int maxArtNoInBasket{0};

    auto iter = std::max_element(sellers_.begin(), sellers_.end(),
-                                 [](const auto &a, const auto &b) -> bool {
+                                 [](const auto& a, const auto& b) -> bool {
                                     return a->getMaxArticleNo() < b->getMaxArticleNo();
                                 });
    if (iter != sellers_.end())
        maxArtNoInDb = (*iter)->getMaxArticleNo();

    auto iter2 =
-        std::max_element(basket_.begin(), basket_.end(), [](const auto &a, const auto &b) -> bool {
+        std::max_element(basket_.begin(), basket_.end(), [](const auto& a, const auto& b) -> bool {
            return a->getArticleNo() < b->getArticleNo();
        });

@ -73,13 +72,13 @@ int Marketplace::getNextArticleNo()
 int Marketplace::getNumSellersDelete()
 {
    int count = std::count_if(sellers_.begin(), sellers_.end(),
-                              [](const auto &a) { return a->getState() == Seller::State::DELETE; });
+                              [](const auto& a) { return a->getState() == Seller::State::DELETE; });
    return count;
 }

 int Marketplace::getNumArticlesSold()
 {
-    int sum = std::accumulate(sellers_.begin(), sellers_.end(), 0, [](int a, const auto &seller) {
+    int sum = std::accumulate(sellers_.begin(), sellers_.end(), 0, [](int a, const auto& seller) {
        return a + seller->numArticlesSold();
    });
    return sum;
@ -87,7 +86,7 @@ int Marketplace::getNumArticlesSold()

 int Marketplace::getNumArticlesOffered()
 {
-    int sum = std::accumulate(sellers_.begin(), sellers_.end(), 0, [](int a, const auto &seller) {
+    int sum = std::accumulate(sellers_.begin(), sellers_.end(), 0, [](int a, const auto& seller) {
        return a + seller->numArticlesOffered();
    });
    return sum;
@ -95,10 +94,19 @@ int Marketplace::getNumArticlesOffered()

 void Marketplace::sortSellers() { std::sort(sellers_.begin(), sellers_.end()); }

-Seller *Marketplace::findSellerWithSellerNo(int sellerNo)
+Seller* Marketplace::findSellerWithSellerNo(int sellerNo)
 {
    auto iter = std::find_if(sellers_.begin(), sellers_.end(),
-                             [sellerNo](const auto &a) { return a->getSellerNo() == sellerNo; });
+                             [sellerNo](const auto& a) { return a->getSellerNo() == sellerNo; });
+    if (iter == sellers_.end())
+        return nullptr;
+    return (*iter).get();
+}
+
+Seller* Marketplace::findSellerWithUuid(const std::string& uuid)
+{
+    auto iter = std::find_if(sellers_.begin(), sellers_.end(),
+                             [uuid](const auto& a) { return a->getUuidAsString() == uuid; });
    if (iter == sellers_.end())
        return nullptr;
    return (*iter).get();
@ -106,8 +114,7 @@ Seller *Marketplace::findSellerWithSellerNo(int sellerNo)

 void Marketplace::addArticleToBasket(std::unique_ptr<Article> article)
 {
-    basket_.insert(basket_.begin(),
-                   std::move(article)); // article to the beginning of the basket vector
+    basket_.insert(basket_.begin(), std::move(article)); // article to the beginning of the basket vector
 }

 size_t Marketplace::basketSize() { return basket_.size(); }
@ -129,12 +136,12 @@ void Marketplace::finishCurrentSale(std::unique_ptr<Sale> sale)
    storeToDb();
 }

-BasketVec &Marketplace::getBasket() { return basket_; }
+BasketVec& Marketplace::getBasket() { return basket_; }

 int Marketplace::getBasketSumInCent()
 {
    int sum = std::accumulate(basket_.begin(), basket_.end(), 0,
-                              [](int a, const auto &b) { return a + b->getPrice(); });
+                              [](int a, const auto& b) { return a + b->getPrice(); });
    return sum;
 }

@ -148,40 +155,39 @@ std::string Marketplace::getBasketSumAsString()
 void Marketplace::removeSale(boost::uuids::uuid uuid)
 {
    sales_.erase(std::remove_if(sales_.begin(), sales_.end(),
-                                [&uuid](const auto &a) { return a->getUuid() == uuid; }),
+                                [&uuid](const auto& a) { return a->getUuid() == uuid; }),
                 sales_.end());
 }

 void Marketplace::setSalesToDelete(int cashPointNo)
 {
-    std::for_each(sales_.begin(), sales_.end(), [cashPointNo](auto &sale) {
+    std::for_each(sales_.begin(), sales_.end(), [cashPointNo](auto& sale) {
        if (sale->getSourceNo() == cashPointNo) {
            sale->setState(Sale::State::DELETE);
-            for (auto &article : sale->getArticles()) {
+            for (auto& article : sale->getArticles()) {
                article->setState(Article::State::DELETE);
            }
        }
    });
 }

-void Marketplace::exportReportToCSV(const fs::path &filePath, int feeInPercent, int maxFeeInEuro)
+void Marketplace::exportReportToCSV(const fs::path& filePath, int feeInPercent, int maxFeeInEuro)
 {
-    const char delimiter = ';';
+    const char delimiter = ',';
    std::ofstream file(filePath);

    file << "Verk.Nr." << delimiter << "Nachname" << delimiter << "Vorname" << delimiter
         << "Anz. gemeldet" << delimiter << "Anz. verkauft" << delimiter << "Umsatz" << delimiter
         << "Auszahlung\n";

-    for (const auto &seller : sellers_) {
+    for (const auto& seller : sellers_) {
        file << seller->getSellerNo() << delimiter
             << escapeCsvValue(seller->getLastName(), delimiter) << delimiter
             << escapeCsvValue(seller->getFirstName(), delimiter) << delimiter
             << seller->numArticlesOffered() << delimiter << seller->numArticlesSold() << delimiter
             << escapeCsvValue(seller->sumAsString(), delimiter) << delimiter
-             << escapeCsvValue(
-                    paymentAsString(seller->sumInCents(), feeInPercent, maxFeeInEuro * 100),
-                    delimiter)
+             << escapeCsvValue(paymentAsString(seller->sumInCents(), feeInPercent, maxFeeInEuro * 100),
+                               delimiter)
             << "\n";
    }
 }
@ -189,7 +195,7 @@ void Marketplace::exportReportToCSV(const fs::path &filePath, int feeInPercent,
 int Marketplace::getOverallSumInCent()
 {
    int sum = std::accumulate(sellers_.begin(), sellers_.end(), 0,
-                              [](int a, const auto &b) { return a + b->sumInCents(); });
+                              [](int a, const auto& b) { return a + b->sumInCents(); });
    return sum;
 }

@ -202,7 +208,7 @@ std::string Marketplace::getOverallSumAsString()
 int Marketplace::getOverallPaymentInCent(int percent, int maxFee)
 {
    int sum = std::accumulate(
-        sellers_.begin(), sellers_.end(), 0, [percent, maxFee](int a, const auto &b) {
+        sellers_.begin(), sellers_.end(), 0, [percent, maxFee](int a, const auto& b) {
            return a + b->sumInCents() - marketFee(b->sumInCents(), percent, maxFee);
        });
    return sum;
@ -240,7 +246,7 @@ std::string paymentAsString(int sumInCent, int percent, int maxFeeInCent)
    return formatCentAsEuroString(sumInCent - marketFee(sumInCent, percent, maxFeeInCent));
 }

-std::string escapeCsvValue(const std::string &value, const char delimiter)
+std::string escapeCsvValue(const std::string& value, const char delimiter)
 {
    std::stringstream output;
    bool containsDelim{false};
@ -250,7 +256,7 @@ std::string escapeCsvValue(const std::string &value, const char delimiter)
        output << '"';
    }

-    for (auto &symbol : value) {
+    for (auto& symbol : value) {
        if (symbol == '"') {
            output << '"' << symbol;
        } else {
--- a/src/core/marketplace.h
+++ b/src/core/marketplace.h
@ -2,7 +2,6 @@
 #define MARKETPLACE_H

 #include "article.h"
-#include "database.h"
 #include "sale.h"
 #include "seller.h"

@ -20,26 +19,26 @@ using BasketVec = std::vector<std::unique_ptr<Article>>;

 class Marketplace
 {
-public:
+  public:
    Marketplace();

    void storeToDb(bool onlyDelete = false);
-    Database::InitResult loadFromDb();
+    void loadFromDb();

-    SellersVec &getSellers();
-    SalesVec &getSales();
+    SellersVec& getSellers();
+    SalesVec& getSales();
    int getNextSellerNo();
    int getNextArticleNo();
    int getNumSellersDelete();
    int getNumArticlesSold();
    int getNumArticlesOffered();
-    BasketVec &getBasket();
+    BasketVec& getBasket();
    int getBasketSumInCent();
    std::string getBasketSumAsString();

    void sortSellers();
-    Seller *findSellerWithSellerNo(int sellerNo);
-    Seller *findSellerWithUuid(const std::string &uuid);
+    Seller* findSellerWithSellerNo(int sellerNo);
+    Seller* findSellerWithUuid(const std::string& uuid);
    void addArticleToBasket(std::unique_ptr<Article> article);
    size_t basketSize();
    void finishCurrentSale(std::unique_ptr<Sale> sale);
@ -54,12 +53,12 @@ public:

    void clear();

-    void exportReportToCSV(const std::filesystem::path &filePath, int feeInPercent,
+    void exportReportToCSV(const std::filesystem::path& filePath, int feeInPercent,
                           int maxFeeInEuro);

    friend class ExcelReader;

-private:
+  private:
    SellersVec sellers_;
    SalesVec sales_;
    BasketVec basket_;
@ -68,6 +67,6 @@ private:
 double marketFee(int sumInCent, int percent, int maxFeeInCent);
 std::string marketFeeAsString(int sumInCent, int percent, int maxFeeInCent);
 std::string paymentAsString(int sumInCent, int percent, int maxFeeInCent);
-std::string escapeCsvValue(const std::string &value, const char delimiter);
+std::string escapeCsvValue(const std::string& value, const char delimiter);

 #endif
--- a/src/core/meson.build
+++ b/src/core/meson.build
@ -1,13 +0,0 @@
-boost = dependency('boost', modules: ['date_time'], static: true)
-xlnt = dependency('xlnt')
-sqlite = dependency('sqlite3')
-
-src = ['database.cpp', 'entity.cpp', 'entityint.cpp', 'entityuuid.cpp',
-       'seller.cpp', 'article.cpp', 'sale.cpp', 'marketplace.cpp',
-       'excelreader.cpp', 'csvreader.cpp', 'jsonutil.cpp', 'utils.cpp']
-
-core_inc = include_directories('..')
-
-core_lib = static_library('core', src, dependencies: [boost, xlnt, sqlite, nlohmann_lib, csv_dep])
-
-core_dep = declare_dependency(link_with: core_lib, include_directories : core_inc)
--- a/src/core/sale.cpp
+++ b/src/core/sale.cpp
@ -3,41 +3,43 @@

 #include <numeric>

-void Sale::addArticle(Article *articlePtr)
+void Sale::addArticle(Article* articlePtr)
 {
    articlePtr->setSale(this);
-    m_articles.push_back(articlePtr);
+    articles_.push_back(articlePtr);
 }

-ArticlesVec &Sale::getArticles() { return m_articles; }
+ArticlesVec& Sale::getArticles() { return articles_; }

-void Sale::removeArticle(const Article *articlePtr)
+void Sale::removeArticle(const Article* articlePtr)
 {
-    auto it = std::find(m_articles.begin(), m_articles.end(), articlePtr);
+    /* auto it = std::find_if(articles_.begin(), articles_.end(),
+                               [&articlePtr](auto art) { return art.get() == articlePtr; }); */
+    auto it = std::find(articles_.begin(), articles_.end(), articlePtr);

-    if (it != m_articles.end()) {
+    if (it != articles_.end()) {
        (*it)->setSale(nullptr);
        (*it)->setState(
            Article::State::DELETE); // since we only have ad-hoc articles, that have all been sold
-        m_articles.erase(it);
+        articles_.erase(it);
    }
 }

 int Sale::sumInCents()
 {
-    int sum = std::accumulate(m_articles.begin(), m_articles.end(), 0,
-                              [](int a, const Article *b) { return a + b->getPrice(); });
+    int sum = std::accumulate(articles_.begin(), articles_.end(), 0,
+                              [](int a, const Article* b) { return a + b->getPrice(); });
    return sum;
 }

 std::string Sale::sumAsString() { return formatCentAsEuroString(sumInCents()); }

-std::string Sale::getTimestamp() const { return m_timestamp; }
+std::string Sale::getTimestamp() const { return timestamp_; }

-void Sale::setTimestamp(const std::string &timestamp) { m_timestamp = timestamp; }
+void Sale::setTimestamp(const std::string& timestamp) { timestamp_ = timestamp; }

 std::string Sale::getTimestampFormatted() const
 {
-    boost::posix_time::ptime time = boost::posix_time::from_iso_extended_string(m_timestamp);
+    boost::posix_time::ptime time = boost::posix_time::from_iso_extended_string(timestamp_);
    return boost::posix_time::to_simple_string(time);
 }
--- a/src/core/sale.h
+++ b/src/core/sale.h
@ -11,30 +11,27 @@

 namespace
 {
-using ArticlesVec = std::vector<Article *>;
+using ArticlesVec = std::vector<Article*>;
 }

-class Sale : public EntityUuid
+class Sale : public Entity
 {
-public:
-    Sale() = default;
-    Sale(const Sale &) = delete;
-    virtual ~Sale() = default;
-    void addArticle(Article *articlePtr);
-    void setTimestamp(const std::string &timestamp);
+  public:
+    void addArticle(Article* articlePtr);
+    void setTimestamp(const std::string& timestamp);

-    ArticlesVec &getArticles();
+    ArticlesVec& getArticles();
    std::string getTimestamp() const;
    std::string getTimestampFormatted() const;
    int sumInCents();
    std::string sumAsString();

-    void removeArticle(const Article *articlePtr);
+    void removeArticle(const Article* articlePtr);

-private:
-    std::string m_timestamp{
+  private:
+    std::string timestamp_{
        boost::posix_time::to_iso_extended_string(boost::posix_time::second_clock::local_time())};
-    mutable ArticlesVec m_articles{};
+    mutable ArticlesVec articles_{};
 };

 #endif
--- a/src/core/seller.cpp
+++ b/src/core/seller.cpp
@ -5,49 +5,50 @@
 #include <numeric>
 #include <sstream>

-Seller::Seller(const std::string &firstName, const std::string &lastName, int sellerNo,
+Seller::Seller(const std::string& firstName, const std::string& lastName, int sellerNo,
               int numArticlesOffered)
-    : EntityInt(sellerNo)
+    : Entity()
 {
-    m_firstName = firstName;
-    m_lastName = lastName;
-    m_numArticlesOffered = numArticlesOffered;
+    firstName_ = firstName;
+    lastName_ = lastName;
+    sellerNo_ = sellerNo;
+    numArticlesOffered_ = numArticlesOffered;
 }

-void Seller::setSellerNo(int seller_no) { setId(seller_no); }
+void Seller::setSellerNo(int seller_no) { sellerNo_ = seller_no; }

-void Seller::setFirstName(const std::string &firstName) { m_firstName = firstName; }
+void Seller::setFirstName(const std::string& firstName) { firstName_ = firstName; }

-void Seller::setLastName(const std::string &lastName) { m_lastName = lastName; }
+void Seller::setLastName(const std::string& lastName) { lastName_ = lastName; }

-void Seller::setNumArticlesOffered(int number) { m_numArticlesOffered = number; }
+void Seller::setNumArticlesOffered(int number) { numArticlesOffered_ = number; }

 void Seller::addArticle(std::unique_ptr<Article> article)
 {
    article->setSeller(this);
-    m_articles.push_back(std::move(article));
+    articles_.push_back(std::move(article));
 }

-std::string Seller::getFirstName() const { return m_firstName; }
+std::string Seller::getFirstName() const { return firstName_; }

-std::string Seller::getLastName() const { return m_lastName; }
+std::string Seller::getLastName() const { return lastName_; }

-int Seller::getSellerNo() const { return getId(); }
+int Seller::getSellerNo() const { return sellerNo_; }

 std::string Seller::getSellerNoAsString() const
 {
    std::stringstream selNoStr;

-    selNoStr << std::setfill('0') << std::setw(3) << m_id;
+    selNoStr << std::setfill('0') << std::setw(3) << sellerNo_;

    return selNoStr.str();
    ;
 }

-std::vector<Article *> Seller::getArticles(bool onlySold) const
+std::vector<Article*> Seller::getArticles(bool onlySold) const
 {
-    std::vector<Article *> articles;
-    for (const auto &article : m_articles) {
+    std::vector<Article*> articles;
+    for (const auto& article : articles_) {
        if (onlySold && article->isSold()) {
            articles.push_back(article.get());
        } else if (!onlySold) {
@ -57,54 +58,54 @@ std::vector<Article *> Seller::getArticles(bool onlySold) const
    return articles;
 }

-Article *Seller::getArticleByUuid(const std::string &uuidString)
+Article* Seller::getArticleByUuid(const std::string& uuidString)
 {
-    auto iter = std::find_if(m_articles.begin(), m_articles.end(), [&uuidString](const auto &art) {
+    auto iter = std::find_if(articles_.begin(), articles_.end(), [&uuidString](const auto& art) {
        return art->getUuidAsString() == uuidString;
    });
-    if (iter == m_articles.end())
+    if (iter == articles_.end())
        return nullptr;
    return (*iter).get();
 }

 int Seller::numArticlesSold() const { return static_cast<int>(getArticles(true).size()); }

-int Seller::numArticlesOffered() const { return m_numArticlesOffered; }
+int Seller::numArticlesOffered() const { return numArticlesOffered_; }

 int Seller::getMaxArticleNo() const
 {
    auto iter = std::max_element(
-        m_articles.begin(), m_articles.end(),
-        [](const auto &a, const auto &b) -> bool { return a->getArticleNo() < b->getArticleNo(); });
-    if (iter == m_articles.end())
+        articles_.begin(), articles_.end(),
+        [](const auto& a, const auto& b) -> bool { return a->getArticleNo() < b->getArticleNo(); });
+    if (iter == articles_.end())
        return 0;
    return (*iter)->getArticleNo();
 }

 void Seller::cleanupArticles()
 {
-    m_articles.erase(std::remove_if(m_articles.begin(), m_articles.end(),
-                                   [](const auto &article) {
+    articles_.erase(std::remove_if(articles_.begin(), articles_.end(),
+                                   [](const auto& article) {
                                       return article->getState() == Article::State::DELETE;
                                   }),
-                    m_articles.end());
+                    articles_.end());

-    for (auto &article : m_articles) {
+    for (auto& article : articles_) {
        article->setState(Article::State::OK);
    }
 }

 int Seller::sumInCents()
 {
-    int sum = std::accumulate(m_articles.begin(), m_articles.end(), 0,
-                              [](int a, const auto &b) { return a + b->getPrice(); });
+    int sum = std::accumulate(articles_.begin(), articles_.end(), 0,
+                              [](int a, const auto& b) { return a + b->getPrice(); });
    return sum;
 }

 std::string Seller::sumAsString() { return formatCentAsEuroString(sumInCents()); }

-bool operator<(const Seller &li, const Seller &re) { return li.m_id < re.m_id; }
-bool operator<(const std::unique_ptr<Seller> &li, const std::unique_ptr<Seller> &re)
+bool operator<(const Seller& li, const Seller& re) { return li.sellerNo_ < re.sellerNo_; }
+bool operator<(const std::unique_ptr<Seller>& li, const std::unique_ptr<Seller>& re)
 {
-    return li->m_id < re->m_id;
+    return li->sellerNo_ < re->sellerNo_;
 }
--- a/src/core/seller.h
+++ b/src/core/seller.h
@ -2,7 +2,7 @@
 #define SELLER_H

 #include "article.h"
-#include "entityint.h"
+#include "entity.h"

 #include <memory>
 #include <string>
@ -10,18 +10,17 @@

 // class Article;

-class Seller : public EntityInt
+class Seller : public Entity
 {
-public:
+  public:
    Seller() = default;
-    Seller(const Seller &) = delete;
-    virtual ~Seller() = default;
-    Seller(const std::string &firstName, const std::string &lastName, int sellerNo = 0,
+    // virtual ~Seller() = default;
+    Seller(const std::string& firstName, const std::string& lastName, int sellerNo = 0,
           int numArticlesOffered = 0);

    void setSellerNo(int sellerNo);
-    void setFirstName(const std::string &firstName);
-    void setLastName(const std::string &lastName);
+    void setFirstName(const std::string& firstName);
+    void setLastName(const std::string& lastName);
    void setNumArticlesOffered(int number);
    void addArticle(std::unique_ptr<Article> article);
    void cleanupArticles();
@ -32,20 +31,22 @@ public:
    std::string getSellerNoAsString() const;
    int numArticlesOffered() const;
    int numArticlesSold() const;
-    std::vector<Article *> getArticles(bool onlySold = true) const;
-    Article *getArticleByUuid(const std::string &uuidString);
+    // int numArticlesTotal() const;
+    std::vector<Article*> getArticles(bool onlySold = true) const;
+    Article* getArticleByUuid(const std::string& uuidString);
    int getMaxArticleNo() const;
    int sumInCents();
    std::string sumAsString();

-    friend bool operator<(const Seller &li, const Seller &re);
-    friend bool operator<(const std::unique_ptr<Seller> &li, const std::unique_ptr<Seller> &re);
+    friend bool operator<(const Seller& li, const Seller& re);
+    friend bool operator<(const std::unique_ptr<Seller>& li, const std::unique_ptr<Seller>& re);

-private:
-    int m_numArticlesOffered{};
-    std::string m_firstName{};
-    std::string m_lastName{};
-    std::vector<std::unique_ptr<Article>> m_articles{};
+  private:
+    int sellerNo_{-1};
+    int numArticlesOffered_{};
+    std::string firstName_{};
+    std::string lastName_{};
+    std::vector<std::unique_ptr<Article>> articles_{};
 };

 #endif
--- a/src/core/utils.cpp
+++ b/src/core/utils.cpp
@ -1,70 +1,46 @@
 #include "utils.h"

-#include <algorithm>
-#include <clocale>
-#include <format>
 #include <iomanip>
 #include <numeric>

-#include <iostream>
-
-//using namespace fmt;
-
 std::string formatCentAsEuroString(const int cent, int width)
 {
-    /*std::stringstream currStream;
+    std::stringstream currStream;

    try {
        std::locale myLocale("de_DE.utf8");
        currStream.imbue(myLocale);
-        std::cout << ">>> " << fmt::format(myLocale, "{:6.2Lf}", 1.12345) << '\n';
        currStream << std::right << std::setw(width) << std::showbase
                   << std::put_money(cent, false);
-    } catch (std::runtime_error &err) {
+    } catch (std::runtime_error& err) {
        currStream << std::fixed << std::setw(width >= 4 ? width - 4 : width)
                   << std::setprecision(2) << cent / 100.0L << " €";
    }

-    return currStream.str();*/
-
-#if defined(_WIN64) || defined(_WIN32)
-    std::locale myLocale;
-#else
-    std::locale myLocale{"de_DE.utf8"};
-#endif
-    return std::format(myLocale, "{:{}.2Lf} €", cent / 100.0L, width);
+    return currStream.str();
 }

-std::string &ltrim(std::string &str, const std::string &chars)
+std::optional<PrinterDevice> convertToPosPrinterDevice(const std::string& device,
+                                                       const std::string& endpoint)
 {
-    str.erase(0, str.find_first_not_of(chars));
-    return str;
-}
+    if (device.empty()) {
+        return std::nullopt;
+    }

-std::string &rtrim(std::string &str, const std::string &chars)
-{
-    str.erase(str.find_last_not_of(chars) + 1);
-    return str;
-}
+    PrinterDevice printerDevice;
+    std::string delimiter = ":";
+    try {
+        printerDevice.idVendor = std::stoi(device.substr(0, device.find(delimiter)), 0, 16);
+        printerDevice.idProduct = std::stoi(device.substr(device.find(delimiter) + 1), 0, 16);
+        if (endpoint.empty()) {
+            printerDevice.endpoint = 0x03;
+        } else {
+            printerDevice.endpoint = std::stoi(endpoint, 0, 16);
+        }

-std::string &trim(std::string &str, const std::string &chars)
-{
-    return ltrim(rtrim(str, chars), chars);
-}
+    } catch (std::exception& ex) {
+        throw ex;
+    }

-bool case_insensitive_match(std::string s1, std::string s2)
-{
-    // convert s1 and s2 into lower case strings
-    transform(s1.begin(), s1.end(), s1.begin(), ::tolower);
-    transform(s2.begin(), s2.end(), s2.begin(), ::tolower);
-    if (s1.compare(s2) == 0)
-        return true; // The strings are same
-    return false;    // not matched
-}
-
-bool isNumber(const std::string &str)
-{
-    return !str.empty() && std::find_if(str.begin(), str.end(), [](unsigned char c) {
-                               return !std::isdigit(c);
-                           }) == str.end();
+    return printerDevice;
 }
--- a/src/core/utils.h
+++ b/src/core/utils.h
@ -1,15 +1,14 @@
-#ifndef CORE_UTILS_H
-#define CORE_UTILS_H
+#ifndef UTILS_H
+#define UTILS_H
+
+#include "posprinter.h"

 #include <locale>
 #include <optional>
 #include <string>

-std::string formatCentAsEuroString(const int cent, int width = 6);
-std::string &ltrim(std::string &str, const std::string &chars = "\t\n\v\f\r ");
-std::string &rtrim(std::string &str, const std::string &chars = "\t\n\v\f\r ");
-std::string &trim(std::string &str, const std::string &chars = "\t\n\v\f\r ");
-bool case_insensitive_match(std::string s1, std::string s2);
-bool isNumber(const std::string &str);
+std::string formatCentAsEuroString(const int cent, int width = 10);
+std::optional<PrinterDevice> convertToPosPrinterDevice(const std::string& vendor,
+                                                       const std::string& endpoint);

 #endif
--- a/src/gui/CMakeLists.txt
+++ b/src/gui/CMakeLists.txt
@ -8,14 +8,8 @@ set(CMAKE_AUTOUIC ON)
 set(CMAKE_AUTORCC ON)

 # Find the QtWidgets library
-find_package(Qt6 COMPONENTS Widgets Network PrintSupport CONFIG REQUIRED)
-#find_package(Qt5Widgets CONFIG REQUIRED)
-#find_package(Qt5PrintSupport CONFIG REQUIRED)
-
-# For SingleApplication:
-#find_package(Qt5Network CONFIG REQUIRED)
-set(QAPPLICATION_CLASS QApplication)
-add_compile_definitions(QAPPLICATION_CLASS=${QAPPLICATION_CLASS})
+find_package(Qt5Widgets CONFIG REQUIRED)
+find_package(Qt5PrintSupport CONFIG REQUIRED)

 set(GUI_SOURCES
    kima2.cpp
@ -34,16 +28,11 @@ set(GUI_SOURCES
    settingsdialog.cpp
    settingsdialog.ui
    ../../kima2.qrc
-    ${PROJECT_SOURCE_DIR}/subprojects/singleapplication/singleapplication.git/singleapplication.cpp
-    ${PROJECT_SOURCE_DIR}/subprojects/singleapplication/singleapplication.git/singleapplication_p.cpp
 )

 add_executable(kima2 ${GUI_SOURCES} kima2.rc)
 target_include_directories(kima2 PRIVATE ${PROJECT_BINARY_DIR})
-target_include_directories(kima2 PRIVATE ${PROJECT_SOURCE_DIR}/subprojects/singleapplication/singleapplication.git)
-# target_link_libraries(kima2 core printer Qt5::Widgets Qt5::PrintSupport Qt5::Network stdc++fs)
-target_link_libraries(kima2 core printer Qt::Core Qt::PrintSupport Qt::Network)
-
+target_link_libraries(kima2 core printer Qt5::Widgets Qt5::PrintSupport stdc++fs)
 if(WIN32)
    set_target_properties(kima2 PROPERTIES LINK_FLAGS "-mwindows")
 endif(WIN32)
--- a/src/gui/basketmodel.cpp
+++ b/src/gui/basketmodel.cpp
@ -1,17 +1,17 @@
 #include "basketmodel.h"

 #include <QFont>
-#include <QFontDatabase>
 #include <QSettings>
+#include <QFontDatabase>

 BasketModel::BasketModel(Marketplace* market, QObject* parent)
-    : QAbstractTableModel(parent), m_marketplace(market)
+    : QAbstractTableModel(parent), marketplace_(market)
 {
 }

 int BasketModel::rowCount([[maybe_unused]] const QModelIndex& parent) const
 {
-    return static_cast<int>(m_marketplace->basketSize());
+    return static_cast<int>(marketplace_->basketSize());
 }

 int BasketModel::columnCount([[maybe_unused]] const QModelIndex& parent) const { return 4; }
@ -22,7 +22,7 @@ QVariant BasketModel::data(const QModelIndex& index, int role) const
        QFont myFont;

        QFont myFixedFont = QFontDatabase::systemFont(QFontDatabase::FixedFont);
-        if (myFixedFont.fixedPitch() == false) {
+	if (myFixedFont.fixedPitch() == false) {
            myFixedFont.setFamily("monospace");
        }

@ -46,10 +46,10 @@ QVariant BasketModel::data(const QModelIndex& index, int role) const
    if (role != Qt::DisplayRole)
        return QVariant();

-    if (m_marketplace->basketSize() == 0)
+    if (marketplace_->basketSize() == 0)
        return QVariant();

-    Article* article = m_marketplace->getBasket().at(index.row()).get();
+    Article* article = marketplace_->getBasket().at(index.row()).get();

    switch (index.column()) {
    case 0:
@ -92,45 +92,45 @@ QVariant BasketModel::headerData(int section, Qt::Orientation orientation, int r

 void BasketModel::addArticle(Seller* seller, int price, const std::string& desc)
 {
-    emit beginInsertRows(QModelIndex(), m_marketplace->getBasket().size(),
-                         m_marketplace->getBasket().size());
+    emit beginInsertRows(QModelIndex(), marketplace_->getBasket().size(),
+                         marketplace_->getBasket().size());
    auto article = std::make_unique<Article>(price);
    article->createUuid();
    article->setDescription(desc);
-    article->setArticleNo(m_marketplace->getNextArticleNo());
+    article->setArticleNo(marketplace_->getNextArticleNo());
    article->setSourceNo(QSettings().value("global/cashPointNo").toInt());
    article->setSeller(seller);
-    m_marketplace->addArticleToBasket(std::move(article));
+    marketplace_->addArticleToBasket(std::move(article));
    emit endInsertRows();
 }

 void BasketModel::finishSale()
 {
-    emit beginRemoveRows(QModelIndex(), 0, m_marketplace->getBasket().size() - 1);
+    emit beginRemoveRows(QModelIndex(), 0, marketplace_->getBasket().size() - 1);
    auto sale = std::make_unique<Sale>();
    sale->createUuid();
    sale->setSourceNo(QSettings().value("global/cashPointNo").toInt());
-    m_marketplace->finishCurrentSale(std::move(sale));
+    marketplace_->finishCurrentSale(std::move(sale));
    emit endRemoveRows();
    emit basketDataChanged();
 }

 void BasketModel::cancelSale()
 {
-    emit beginRemoveRows(QModelIndex(), 0, m_marketplace->getBasket().size() - 1);
-    m_marketplace->getBasket().clear();
+    emit beginRemoveRows(QModelIndex(), 0, marketplace_->getBasket().size() - 1);
+    marketplace_->getBasket().clear();
    emit endRemoveRows();
 }

 bool BasketModel::removeRows(int row, int count, const QModelIndex& parent)
 {
-    auto article = m_marketplace->getBasket().at(row).get();
+    auto article = marketplace_->getBasket().at(row).get();

    emit beginRemoveRows(parent, row, row + count - 1);
-    m_marketplace->getBasket().erase(
-        std::remove_if(m_marketplace->getBasket().begin(), m_marketplace->getBasket().end(),
+    marketplace_->getBasket().erase(
+        std::remove_if(marketplace_->getBasket().begin(), marketplace_->getBasket().end(),
                       [&article](const auto& a) { return a->getUuid() == article->getUuid(); }),
-        m_marketplace->getBasket().end());
+        marketplace_->getBasket().end());
    emit endRemoveRows();
    return true;
 }
--- a/src/gui/basketmodel.h
+++ b/src/gui/basketmodel.h
@ -1,13 +1,13 @@
 #ifndef BASKET_MODEL_H
 #define BASKET_MODEL_H

-#include <core/marketplace.h>
+#include <marketplace.h>

 #include <QAbstractTableModel>

 class BasketModel : public QAbstractTableModel
 {
-    Q_OBJECT
+  Q_OBJECT

  public:
    explicit BasketModel(Marketplace* market, QObject* parent = nullptr);
@ -15,16 +15,19 @@ class BasketModel : public QAbstractTableModel
    virtual int columnCount(const QModelIndex& parent = QModelIndex()) const override;
    virtual QVariant data(const QModelIndex& index, int role = Qt::DisplayRole) const override;
    virtual QVariant headerData(int section, Qt::Orientation orientation, int role) const override;
+    //virtual Qt::ItemFlags flags(const QModelIndex& index) const override;
+    //virtual bool setData(const QModelIndex& index, const QVariant& value, int role = Qt::EditRole) override;
+    //virtual bool insertRows(int row, int count, const QModelIndex& parent = QModelIndex()) override;
    void addArticle(Seller* seller, int price, const std::string& desc);
    void finishSale();
    void cancelSale();
    virtual bool removeRows(int row, int count, const QModelIndex& parent = QModelIndex()) override;

-  signals:
+    signals:
    void basketDataChanged();

  private:
-    Marketplace* m_marketplace;
+    Marketplace* marketplace_;
 };

 #endif
--- a/src/gui/kima2.cpp
+++ b/src/gui/kima2.cpp
@ -6,27 +6,26 @@
 #include <QLibraryInfo>
 #include <QMessageBox>
 #include <QSettings>
-#include <QSharedMemory>
-#include <QStyleFactory>
 #include <QTranslator>

-#include <singleapplication.h>
-#include <stdexcept>
-
-int main(int argc, char *argv[])
+int main(int argc, char* argv[])
 {
-    SingleApplication kimaApp(argc, argv, false, SingleApplication::Mode::User | SingleApplication::ExcludeAppPath | SingleApplication::ExcludeAppVersion);
+    QApplication kimaApp{argc, argv};

    // QCoreApplication::setOrganizationName("RustySoft");
    QCoreApplication::setOrganizationDomain("rustysoft.de");
    QCoreApplication::setApplicationName("kima2");

-    QTranslator qtTranslator;
-
-    if (qtTranslator.load(QLocale::system(), u"qtbase"_qs, u"_"_qs,
-                         QLibraryInfo::path(QLibraryInfo::TranslationsPath))) {
-        kimaApp.installTranslator(&qtTranslator);
-    }
+    QTranslator qTranslator;
+    QLocale german(QLocale::German);
+#ifdef __linux__
+    qTranslator.load("qt_" + german.name(), QLibraryInfo::location(QLibraryInfo::TranslationsPath));
+#endif
+#ifdef _WIN32
+    qTranslator.load("qt_" + german.name(),
+                     QApplication::applicationDirPath() + QDir::separator() + "translations");
+#endif
+    kimaApp.installTranslator(&qTranslator);

    QSettings settings{};
    while (!settings.contains("global/cashPointNo")) {
--- a/src/gui/mainwindow.cpp
+++ b/src/gui/mainwindow.cpp
@ -1,23 +1,22 @@
 #include "mainwindow.h"

 #include "basketmodel.h"
+#include "config.h"
+#include "jsonutil.h"
 #include "pricedialog.h"
 #include "reportdialog.h"
 #include "salemodel.h"
 #include "sellerdialog.h"
 #include "settingsdialog.h"
-#include <config.h>

-#include <core/csvreader.h>
-#include <core/jsonutil.h>
-#include <core/utils.h>
-#include <printer/posprinter.h>
-#include <printer/utils.h>
+#include <utils.h>
+
+#include <excelreader.h>
+#include <posprinter.h>

 #include <exception>
 #include <filesystem>
 #include <regex>
-#include <string>

 #include <QFileDialog>
 #include <QMessageBox>
@ -31,31 +30,23 @@ constexpr int STATUSBAR_TIMEOUT = 5000;

 MainWindow::MainWindow()
 {
-    m_ui.setupUi(this);
+    ui_.setupUi(this);

-    m_marketplace = std::make_unique<Marketplace>();
-    Database::InitResult res = m_marketplace->loadFromDb();
-    if (res == Database::InitResult::OUTDATED_REPLACED) {
-        QMessageBox(QMessageBox::Icon::Information, "Datenbankinformation",
-                    "Es wurde eine <b>veraltete</b> Datenbankdatei erkannt.<br />Diese wurde "
-                    "umbenannt und eine <b>neue</b> Datei wurde erstellt.")
-            .exec();
-    }
+    marketplace_ = std::make_unique<Marketplace>();
+    marketplace_->loadFromDb();
    statusBar()->showMessage("Gespeicherte Daten wurden geladen.", STATUSBAR_TIMEOUT);

-    BasketModel *model = new BasketModel(getMarketplace(), m_ui.basketView);
-    m_ui.basketView->setModel(model);
-    m_ui.basketView->setColumnHidden(0, true); // hide the uuid
+    BasketModel* model = new BasketModel(getMarketplace(), ui_.basketView);
+    ui_.basketView->setModel(model);
+    ui_.basketView->setColumnHidden(0, true); // hide the uuid

    setWindowTitle("KIMA2 - Kasse Nr. " + QSettings().value("global/cashPointNo").toString());

-    m_ui.salesView->header()->setSectionResizeMode(QHeaderView::ResizeToContents);
    setSaleModel();

-    connect(m_ui.actionQuit, &QAction::triggered, qApp, QApplication::closeAllWindows,
-            Qt::QueuedConnection);
-    connect(m_ui.newAction, &QAction::triggered, this, [this]() {
-        if (m_marketplace->getSellers().size() == 0 && m_marketplace->getSales().size() == 0) {
+    connect(ui_.actionQuit, &QAction::triggered, qApp, QApplication::quit);
+    connect(ui_.newAction, &QAction::triggered, this, [=]() {
+        if (marketplace_->getSellers().size() == 0 && marketplace_->getSales().size() == 0) {
            return;
        }
        auto dlgResult =
@ -67,45 +58,46 @@ MainWindow::MainWindow()
        if (dlgResult == QMessageBox::No)
            return;

-        delete m_ui.salesView->model();
-        dynamic_cast<BasketModel *>(m_ui.basketView->model())->cancelSale();
-        m_marketplace->clear();
+        delete ui_.salesView->model();
+        dynamic_cast<BasketModel*>(ui_.basketView->model())->cancelSale();
+        marketplace_->clear();
        setSaleModel();
        updateStatLabel();
    });

-    m_ui.sellerNoEdit->installEventFilter(this);
-    m_ui.givenSpinBox->installEventFilter(this);
+    ui_.sellerNoEdit->installEventFilter(this);
+    ui_.givenSpinBox->installEventFilter(this);

-    connect(m_ui.actionEditSeller, &QAction::triggered, this,
+    connect(ui_.actionEditSeller, &QAction::triggered, this,
            &MainWindow::onActionEditSellerTriggered);
-    connect(m_ui.paidButton, &QPushButton::clicked, this, &MainWindow::onPaidButtonTriggered);
-    connect(m_ui.givenSpinBox, QOverload<double>::of(&QDoubleSpinBox::valueChanged), this,
+    connect(ui_.paidButton, &QPushButton::clicked, this, &MainWindow::onPaidButtonTriggered);
+    connect(ui_.givenSpinBox, QOverload<double>::of(&QDoubleSpinBox::valueChanged), this,
            &MainWindow::onGivenSpinBoxValueChanged);
-    connect(m_ui.basketView->selectionModel(), &QItemSelectionModel::selectionChanged, this,
+    connect(ui_.basketView->selectionModel(), &QItemSelectionModel::selectionChanged, this,
            &MainWindow::onBasketViewSelectionChanged);
-    connect(m_ui.cancelArticleButton, &QPushButton::clicked, this,
+    connect(ui_.cancelArticleButton, &QPushButton::clicked, this,
            &MainWindow::onCancelArticleButtonClicked);
-    connect(m_ui.cancelSaleButton, &QPushButton::clicked, this,
+    connect(ui_.cancelSaleButton, &QPushButton::clicked, this,
            &MainWindow::onCancelSaleButtonClicked);
-    connect(m_ui.printSaleReceiptButton, &QPushButton::clicked, this,
+    connect(ui_.printSaleReceiptButton, &QPushButton::clicked, this,
            &MainWindow::onPrintSaleReceiptButtonClicked);
-    connect(m_ui.cancelAllArticlesButton, &QPushButton::clicked, this,
+    connect(ui_.cancelAllArticlesButton, &QPushButton::clicked, this,
            &MainWindow::onCancelAllArticlesButtonClicked);
-    connect(m_ui.aboutQtAction, &QAction::triggered, this, &MainWindow::onAboutQt);
-    connect(m_ui.aboutAction, &QAction::triggered, this, &MainWindow::onAbout);
-    connect(m_ui.openManualAction, &QAction::triggered, this, []() {
-        auto locations = QStandardPaths::standardLocations(QStandardPaths::AppDataLocation);
+    connect(ui_.aboutQtAction, &QAction::triggered, this, &MainWindow::onAboutQt);
+    connect(ui_.aboutAction, &QAction::triggered, this, &MainWindow::onAbout);
+    connect(ui_.openManualAction, &QAction::triggered, this, []() {
+        auto locations = QStandardPaths::standardLocations(QStandardPaths::DataLocation);
        for (auto location : locations) {
            if (QFile::exists(location + QString("/Benutzerhandbuch.pdf"))) {
                QDesktopServices::openUrl(
-                    QUrl::fromLocalFile(location + QString("/Benutzerhandbuch.pdf")));
+                    QUrl(QString("file:///") + location + QString("/Benutzerhandbuch.pdf"),
+                         QUrl::TolerantMode));
            }
        }
    });
-    connect(m_ui.licenseAction, &QAction::triggered, this, [this]() {
+    connect(ui_.licenseAction, &QAction::triggered, this, [=]() {
        QString licenseText(
-            "Copyright © 2018-2024 Martin Brodbeck\n\n"
+            "Copyright © 2018 Martin Brodbeck\n\n"
            "Hiermit wird unentgeltlich jeder Person, die eine Kopie der Software und der "
            "zugehörigen Dokumentationen (die \"Software\") erhält, die Erlaubnis erteilt, "
            "sie uneingeschränkt zu nutzen, inklusive und ohne Ausnahme mit dem Recht, "
@ -124,30 +116,32 @@ MainWindow::MainWindow()
            "SOFTWARE ODER SONSTIGER VERWENDUNG DER SOFTWARE ENTSTANDEN.");
        QMessageBox::information(this, "Lizenzinformation", licenseText);
    });
-    connect(m_ui.reportAction, &QAction::triggered, this, [this]() { ReportDialog(this).exec(); });
-    connect(m_ui.configAction, &QAction::triggered, this, [this]() {
+    connect(ui_.reportAction, &QAction::triggered, this, [=]() { ReportDialog(this).exec(); });
+    connect(ui_.configAction, &QAction::triggered, this, [=]() {
        int result = SettingsDialog(this).exec();
        if (result == QDialog::Accepted) {
-            delete m_ui.salesView->model();
-            m_marketplace->loadFromDb();
+            delete ui_.salesView->model();
+            marketplace_->loadFromDb();
            setSaleModel();
        }
        this->setWindowTitle("KIMA2 - Kasse Nr. " +
                             QSettings().value("global/cashPointNo").toString());
    });
-    connect(m_ui.importSellerAction, &QAction::triggered, this,
-            &MainWindow::onImportSellerActionTriggered);
-    connect(m_ui.exportSalesJsonAction, &QAction::triggered, this,
+    connect(ui_.importSellerExcelAction, &QAction::triggered, this,
+            &MainWindow::onImportSellerExcelActionTriggered);
+    connect(ui_.importSellerJsonAction, &QAction::triggered, this,
+            &MainWindow::onImportSellerJsonActionTriggered);
+    connect(ui_.exportSellerJsonAction, &QAction::triggered, this,
+            &MainWindow::onExportSellerJsonActionTriggered);
+    connect(ui_.exportSalesJsonAction, &QAction::triggered, this,
            &MainWindow::onExportSalesJsonActionTriggered);
-    connect(m_ui.importSalesJsonAction, &QAction::triggered, this,
+    connect(ui_.importSalesJsonAction, &QAction::triggered, this,
            &MainWindow::onImportSalesJsonActionTriggered);

    readGeometry();
    setWindowIcon(QIcon(":/misc/kima2.ico"));

    updateStatLabel();
-    m_ui.lastPriceLabel1->setText(formatCentAsEuroString(0).c_str());
-    m_ui.lastPriceLabel2->setText(formatCentAsEuroString(0).c_str());
 }

 void MainWindow::onActionEditSellerTriggered()
@ -155,11 +149,11 @@ void MainWindow::onActionEditSellerTriggered()
    auto dialog = std::make_unique<SellerDialog>(this);
    int retCode = dialog->exec();

-    delete m_ui.salesView->model();
+    delete ui_.salesView->model();

    if (retCode == QDialog::Accepted) {
-        m_marketplace->sortSellers();
-        m_marketplace->storeToDb();
+        marketplace_->sortSellers();
+        marketplace_->storeToDb();
        statusBar()->showMessage("Änderungen an den Verkäufer-Stammdaten gespeichert.",
                                 STATUSBAR_TIMEOUT);
    } else {
@ -173,44 +167,43 @@ void MainWindow::onActionEditSellerTriggered()

 void MainWindow::setSaleModel()
 {
-    m_ui.salesView->setModel(new SaleModel(getMarketplace(), m_ui.salesView));
-    m_ui.salesView->setColumnHidden(2, true);
-    m_ui.salesView->resizeColumnToContents(0);
-    m_ui.salesView->resizeColumnToContents(1);
+    ui_.salesView->setModel(new SaleModel(getMarketplace(), ui_.salesView));
+    ui_.salesView->setColumnHidden(2, true);
+    ui_.salesView->resizeColumnToContents(0);

-    m_ui.printSaleReceiptButton->setEnabled(false);
-    m_ui.cancelSaleButton->setEnabled(false);
+    ui_.printSaleReceiptButton->setEnabled(false);
+    ui_.cancelSaleButton->setEnabled(false);

-    connect(static_cast<BasketModel *>(m_ui.basketView->model()), &BasketModel::basketDataChanged,
-            static_cast<SaleModel *>(m_ui.salesView->model()), &SaleModel::onBasketDataChanged);
-    connect(m_ui.salesView->selectionModel(), &QItemSelectionModel::selectionChanged, this,
+    connect(static_cast<BasketModel*>(ui_.basketView->model()), &BasketModel::basketDataChanged,
+            static_cast<SaleModel*>(ui_.salesView->model()), &SaleModel::onBasketDataChanged);
+    connect(ui_.salesView->selectionModel(), &QItemSelectionModel::selectionChanged, this,
            &MainWindow::onSalesViewSelectionChanged);
 }

 void MainWindow::onPaidButtonTriggered()
 {
-    if (m_marketplace->basketSize() > 0) {
-        QString lastPrice{m_marketplace->getBasketSumAsString().c_str()};
-        dynamic_cast<BasketModel *>(m_ui.basketView->model())->finishSale();
-        m_ui.salesView->resizeColumnToContents(0);
-        m_ui.lastPriceLabel1->setText(lastPrice);
-        m_ui.lastPriceLabel2->setText(lastPrice);
-        m_ui.basketSumLabel->setText(formatCentAsEuroString(0).c_str());
-        m_ui.drawbackLabel->setText(formatCentAsEuroString(0).c_str());
-        m_ui.drawbackContainerWidget->setEnabled(false);
-        m_ui.sellerNoEdit->setFocus();
+    if (marketplace_->basketSize() > 0) {
+        QString lastPrice{marketplace_->getBasketSumAsString().c_str()};
+        dynamic_cast<BasketModel*>(ui_.basketView->model())->finishSale();
+        ui_.salesView->resizeColumnToContents(0);
+        ui_.lastPriceLabel1->setText(lastPrice);
+        ui_.lastPriceLabel2->setText(lastPrice);
+        ui_.basketSumLabel->setText(formatCentAsEuroString(0).c_str());
+        ui_.drawbackLabel->setText(formatCentAsEuroString(0).c_str());
+        ui_.drawbackContainerWidget->setEnabled(false);
+        ui_.sellerNoEdit->setFocus();
        statusBar()->showMessage("Verkaufsvorgang erfolgreich durchgeführt.", STATUSBAR_TIMEOUT);
        updateStatLabel();
    }
 }

-bool MainWindow::eventFilter(QObject *target, QEvent *event)
+bool MainWindow::eventFilter(QObject* target, QEvent* event)
 {
-    if (target == m_ui.sellerNoEdit) {
+    if (target == ui_.sellerNoEdit) {
        if (event->type() == QEvent::KeyPress) {
-            QKeyEvent *keyEvent = static_cast<QKeyEvent *>(event);
+            QKeyEvent* keyEvent = static_cast<QKeyEvent*>(event);
            if (keyEvent->key() == Qt::Key::Key_Enter || keyEvent->key() == Qt::Key::Key_Return) {
-                if (keyEvent->modifiers() & Qt::ControlModifier) {
+                if (keyEvent->modifiers() == Qt::ControlModifier) {
                    checkSellerNo(true);
                } else {
                    checkSellerNo(false);
@ -219,18 +212,18 @@ bool MainWindow::eventFilter(QObject *target, QEvent *event)
                return true;
            }
        }
-    } else if (target == m_ui.givenSpinBox) {
+    } else if (target == ui_.givenSpinBox) {
        if (event->type() == QEvent::KeyPress) {
-            QKeyEvent *keyEvent = static_cast<QKeyEvent *>(event);
+            QKeyEvent* keyEvent = static_cast<QKeyEvent*>(event);
            if (keyEvent->key() == Qt::Key::Key_Enter || keyEvent->key() == Qt::Key::Key_Return) {
-                if (keyEvent->modifiers() & Qt::ControlModifier) {
+                if (keyEvent->modifiers() == Qt::ControlModifier) {
                    onPaidButtonTriggered();
                    return true;
                }
            } else if (keyEvent->key() == Qt::Key::Key_Escape) {
-                m_ui.drawbackLabel->setText(formatCentAsEuroString(0).c_str());
-                m_ui.drawbackContainerWidget->setEnabled(false);
-                m_ui.sellerNoEdit->setFocus();
+                ui_.drawbackLabel->setText(formatCentAsEuroString(0).c_str());
+                ui_.drawbackContainerWidget->setEnabled(false);
+                ui_.sellerNoEdit->setFocus();
            }
        }
    }
@ -241,15 +234,15 @@ void MainWindow::checkSellerNo(bool ctrlPressed)
 {
    using std::regex, std::regex_match, std::smatch;

-    auto inputText = m_ui.sellerNoEdit->text().toStdString();
+    auto inputText = ui_.sellerNoEdit->text().toStdString();

    if (inputText.empty()) {
        if (ctrlPressed == false) {
            onPaidButtonTriggered();
-        } else if (m_marketplace->getBasket().size() > 0) {
-            m_ui.drawbackContainerWidget->setEnabled(true);
-            m_ui.givenSpinBox->setFocus();
-            m_ui.givenSpinBox->selectAll();
+        } else if (marketplace_->getBasket().size() > 0) {
+            ui_.drawbackContainerWidget->setEnabled(true);
+            ui_.givenSpinBox->setFocus();
+            ui_.givenSpinBox->selectAll();
        }
        return;
    }
@ -258,13 +251,13 @@ void MainWindow::checkSellerNo(bool ctrlPressed)
    smatch result;

    if (!regex_match(inputText, result, pattern)) {
-        m_ui.sellerNoEdit->clear();
+        ui_.sellerNoEdit->clear();
        return;
    }

    int sellerNo = std::stoi(result[0]);

-    auto seller = m_marketplace->findSellerWithSellerNo(sellerNo);
+    auto seller = marketplace_->findSellerWithSellerNo(sellerNo);
    if (seller) {
        PriceDialog priceDialog(this);
        if (sellerNo == 0) {
@ -274,52 +267,52 @@ void MainWindow::checkSellerNo(bool ctrlPressed)
        if (dialogResult == QDialog::Accepted) {
            int price = priceDialog.getPrice();
            std::string desc = priceDialog.getDescription();
-            dynamic_cast<BasketModel *>(m_ui.basketView->model())->addArticle(seller, price, desc);
-            m_ui.basketView->resizeColumnToContents(1);
-            m_ui.basketSumLabel->setText(m_marketplace->getBasketSumAsString().c_str());
+            dynamic_cast<BasketModel*>(ui_.basketView->model())->addArticle(seller, price, desc);
+            ui_.basketView->resizeColumnToContents(1);
+            ui_.basketSumLabel->setText(marketplace_->getBasketSumAsString().c_str());
        }
    }

-    m_ui.sellerNoEdit->clear();
+    ui_.sellerNoEdit->clear();
 }

 void MainWindow::onGivenSpinBoxValueChanged(double value)
 {
    int givenInCent = std::round(value * 100);
-    int basketSumInCent = m_marketplace->getBasketSumInCent();
+    int basketSumInCent = marketplace_->getBasketSumInCent();
    int drawback = givenInCent - basketSumInCent;
-    m_ui.drawbackLabel->setText(formatCentAsEuroString(drawback).c_str());
+    ui_.drawbackLabel->setText(formatCentAsEuroString(drawback).c_str());
 }

-void MainWindow::onBasketViewSelectionChanged(const QItemSelection &selected,
-                                              [[maybe_unused]] const QItemSelection &deselected)
+void MainWindow::onBasketViewSelectionChanged(const QItemSelection& selected,
+                                              [[maybe_unused]] const QItemSelection& deselected)
 {
    if (selected.size() > 0) {
-        m_ui.cancelArticleButton->setEnabled(true);
+        ui_.cancelArticleButton->setEnabled(true);
    } else {
-        m_ui.cancelArticleButton->setEnabled(false);
+        ui_.cancelArticleButton->setEnabled(false);
    }
 }

-void MainWindow::onSalesViewSelectionChanged(const QItemSelection &selected,
-                                             [[maybe_unused]] const QItemSelection &deselected)
+void MainWindow::onSalesViewSelectionChanged(const QItemSelection& selected,
+                                             [[maybe_unused]] const QItemSelection& deselected)
 {
    if (selected.size() > 0) {
-        m_ui.cancelSaleButton->setEnabled(true);
+        ui_.cancelSaleButton->setEnabled(true);
        if (!selected.indexes()[0].parent().isValid())
-            m_ui.printSaleReceiptButton->setEnabled(true);
+            ui_.printSaleReceiptButton->setEnabled(true);
        else
-            m_ui.printSaleReceiptButton->setEnabled(false);
+            ui_.printSaleReceiptButton->setEnabled(false);

    } else {
-        m_ui.cancelSaleButton->setEnabled(false);
-        m_ui.printSaleReceiptButton->setEnabled(false);
+        ui_.cancelSaleButton->setEnabled(false);
+        ui_.printSaleReceiptButton->setEnabled(false);
    }
 }

 void MainWindow::onCancelArticleButtonClicked([[maybe_unused]] bool checked)
 {
-    auto selModel = m_ui.basketView->selectionModel();
+    auto selModel = ui_.basketView->selectionModel();
    if (selModel->hasSelection() == false)
        return;

@ -336,23 +329,22 @@ void MainWindow::onCancelArticleButtonClicked([[maybe_unused]] bool checked)

    // Deleting the rows, beginning with the last one!
    for (auto iter = indexes.constEnd() - 1; iter >= indexes.constBegin(); --iter) {
-        m_ui.basketView->model()->removeRow(iter->row());
+        ui_.basketView->model()->removeRow(iter->row());
    }

-    m_ui.basketSumLabel->setText(
-        m_marketplace->getBasketSumAsString().c_str()); // Update basket sum
-    m_ui.sellerNoEdit->setFocus();
+    ui_.basketSumLabel->setText(marketplace_->getBasketSumAsString().c_str()); // Update basket sum
+    ui_.sellerNoEdit->setFocus();
 }

 void MainWindow::onCancelSaleButtonClicked([[maybe_unused]] bool checked)
 {
-    auto selModel = m_ui.salesView->selectionModel();
+    auto selModel = ui_.salesView->selectionModel();
    if (selModel->hasSelection() == false)
        return;

    auto dlgResult =
        QMessageBox(QMessageBox::Icon::Warning, "Sind Sie sicher?",
-                    "Möchten Sie wirklich aus abgeschlossenen Verkäufen stornieren?",
+                    "Möchten Sie wirklich stornieren?",
                    QMessageBox::StandardButton::Yes | QMessageBox::StandardButton::No, this)
            .exec();
    if (dlgResult == QMessageBox::No)
@ -363,25 +355,16 @@ void MainWindow::onCancelSaleButtonClicked([[maybe_unused]] bool checked)

    // Deleting the rows, beginning with the last one!
    for (auto iter = indexes.constEnd() - 1; iter >= indexes.constBegin(); --iter) {
-        m_ui.salesView->model()->removeRow(iter->row(), iter->parent());
+        ui_.salesView->model()->removeRow(iter->row(), iter->parent());
    }

-    m_ui.salesView->collapseAll();
-
-    QString lastPriceValue(formatCentAsEuroString(0).c_str());
-    if (m_ui.salesView->model()->rowCount() > 0) {
-        lastPriceValue =
-            m_ui.salesView->model()->data(m_ui.salesView->model()->index(0, 1)).toString();
-    }
-    m_ui.lastPriceLabel1->setText(lastPriceValue);
-    m_ui.lastPriceLabel2->setText(lastPriceValue);
-
+    ui_.salesView->collapseAll();
    updateStatLabel();
 }

 void MainWindow::onPrintSaleReceiptButtonClicked([[maybe_unused]] bool checked)
 {
-    auto selModel = m_ui.salesView->selectionModel();
+    auto selModel = ui_.salesView->selectionModel();
    if (selModel->hasSelection() == false)
        return;

@ -390,7 +373,7 @@ void MainWindow::onPrintSaleReceiptButtonClicked([[maybe_unused]] bool checked)
    QString posPrinterEndpoint = settings.value("global/posPrinterEndpoint", "").toString();

    auto indexes = selModel->selectedRows();
-    auto &sale = m_marketplace->getSales().at(indexes[0].row());
+    auto& sale = marketplace_->getSales().at(indexes[0].row());

    auto printerDevice =
        convertToPosPrinterDevice(posPrinterDevice.toStdString(), posPrinterEndpoint.toStdString());
@ -404,13 +387,12 @@ void MainWindow::onPrintSaleReceiptButtonClicked([[maybe_unused]] bool checked)
    }

    if (printer->isValid())
-        printer->printSaleReceipt(
-            sale.get(), settings.value("global/commune", "Dettingen").toString().toStdString());
+        printer->printSaleReceipt(sale.get(), settings.value("global/commune", "Dettingen").toString().toStdString());
 }

 void MainWindow::onCancelAllArticlesButtonClicked([[maybe_unused]] bool checked)
 {
-    if (m_ui.basketView->model()->rowCount() == 0)
+    if (ui_.basketView->model()->rowCount() == 0)
        return;

    auto dlgResult =
@ -421,11 +403,10 @@ void MainWindow::onCancelAllArticlesButtonClicked([[maybe_unused]] bool checked)
    if (dlgResult == QMessageBox::No)
        return;

-    dynamic_cast<BasketModel *>(m_ui.basketView->model())->cancelSale();
+    dynamic_cast<BasketModel*>(ui_.basketView->model())->cancelSale();

-    m_ui.basketSumLabel->setText(
-        m_marketplace->getBasketSumAsString().c_str()); // Update basket sum
-    m_ui.sellerNoEdit->setFocus();
+    ui_.basketSumLabel->setText(marketplace_->getBasketSumAsString().c_str()); // Update basket sum
+    ui_.sellerNoEdit->setFocus();
 }

 void MainWindow::onAboutQt() { QMessageBox::aboutQt(this); }
@ -441,9 +422,9 @@ void MainWindow::onAbout()
            ">info@rustysoft.de</a>&gt;</p>");
 }

-void MainWindow::onImportSellerActionTriggered()
+void MainWindow::onImportSellerExcelActionTriggered()
 {
-    if (!m_marketplace->getSales().empty()) {
+    if (!marketplace_->getSales().empty()) {
        QMessageBox(QMessageBox::Icon::Information, "Import nicht möglich",
                    "Der Import ist nicht möglich, da schon Verkäufe getätigt wurden.",
                    QMessageBox::StandardButton::Ok, this)
@ -451,31 +432,59 @@ void MainWindow::onImportSellerActionTriggered()
        return;
    }

-    auto filename =
-        QFileDialog::getOpenFileName(this, "Verkäufer importieren", QString(),
-                                     "Alle unterstützte Dateien (*.csv);;CSV Dateien (*.csv)");
+    QMessageBox(
+        QMessageBox::Icon::Information, "Bitte beachten",
+        "<b>Achtung:</b> Importieren Sie die Verkäuferdaten nur auf <b>einer (!)</b> "
+        "KIMA2-Installation.<br /> "
+        "Verteilen Sie die Daten auf die anderen Installationen unbedingt über eine JSON-Datei!",
+        QMessageBox::StandardButton::Ok, this)
+        .exec();
+
+    auto filename = QFileDialog::getOpenFileName(this, "Verkäufer importieren", QString(),
+                                                 "Excel Dateien (*.xlsx *.xls)");

    if (filename.isEmpty())
        return;

-#if defined(_WIN64) || defined(_WIN32)
    fs::path filePath(filename.toStdWString());
-#else
-    fs::path filePath(filename.toStdString());
-#endif
-
-    std::size_t numImported{};
-    numImported = CsvReader::readSellersFromFile(filePath, m_marketplace.get());

+    ExcelReader::readSellersFromFile(filePath, marketplace_.get());
    updateStatLabel();
+}

-    using namespace std::string_literals;
-    std::ostringstream msg;
-    msg << "Aus der CSV-Datei wurden <b>"s << std::to_string(numImported)
-        << "</b> Verkäufer importiert.";
-    QMessageBox(QMessageBox::Icon::Information, "Verkäufer erfolgreich importiert",
-                msg.str().c_str(), QMessageBox::StandardButton::Ok, this)
-        .exec();
+void MainWindow::onImportSellerJsonActionTriggered()
+{
+    if (!marketplace_->getSales().empty()) {
+        QMessageBox(QMessageBox::Icon::Information, "Import nicht möglich",
+                    "Der Import ist nicht möglich, da schon Verkäufe getätigt wurden.",
+                    QMessageBox::StandardButton::Ok, this)
+            .exec();
+        return;
+    }
+
+    auto filename = QFileDialog::getOpenFileName(this, "Verkäufer importieren", QString(),
+                                                 "JSON Dateien (*.json)");
+
+    if (filename.isEmpty())
+        return;
+
+    fs::path filePath(filename.toStdWString());
+
+    JsonUtil::importSellers(filePath, marketplace_.get());
+    updateStatLabel();
+}
+
+void MainWindow::onExportSellerJsonActionTriggered()
+{
+    auto filename = QFileDialog::getSaveFileName(
+        this, "Verkäufer exportieren", QString("kima2_verkaeufer.json"), "JSON Dateien (*.json)");
+
+    if (filename.isEmpty())
+        return;
+
+    fs::path filePath(filename.toStdWString());
+
+    JsonUtil::exportSellers(filePath, marketplace_.get());
 }

 void MainWindow::onExportSalesJsonActionTriggered()
@ -490,13 +499,9 @@ void MainWindow::onExportSalesJsonActionTriggered()
    if (filename.isEmpty())
        return;

-#if defined(_WIN64) || defined(_WIN32)
    fs::path filePath(filename.toStdWString());
-#else
-    fs::path filePath(filename.toStdString());
-#endif

-    JsonUtil::exportSales(filePath, m_marketplace.get(),
+    JsonUtil::exportSales(filePath, marketplace_.get(),
                          settings.value("global/cashPointNo").toInt());
 }

@ -504,30 +509,23 @@ void MainWindow::onImportSalesJsonActionTriggered()
 {
    QSettings settings;

-    auto filenames = QFileDialog::getOpenFileNames(this, "Umsätze/Transaktionen importieren",
+    auto filename = QFileDialog::getOpenFileName(this, "Umsätze/Transaktionen importieren",
                                                 QString(), "JSON Dateien (*.json)");

-    if (filenames.isEmpty())
+    if (filename.isEmpty())
        return;

-    for(auto filename: filenames) {
-#if defined(_WIN64) || defined(_WIN32)
-        fs::path filePath(filename.toStdWString());
-#else
-        fs::path filePath(filename.toStdString());
-#endif
+    fs::path filePath(filename.toStdWString());

-        delete m_ui.salesView->model();
-        try {
-            JsonUtil::importSales(filePath, m_marketplace.get(),
-                                settings.value("global/cashPointNo").toInt());
-        } catch (std::runtime_error &err) {
-            QMessageBox(QMessageBox::Icon::Warning, "Import nicht möglich", err.what(), QMessageBox::Ok,
-                        this)
-                .exec();
-        }
+    delete ui_.salesView->model();
+    try {
+        JsonUtil::importSales(filePath, marketplace_.get(),
+                              settings.value("global/cashPointNo").toInt());
+    } catch (std::runtime_error& err) {
+        QMessageBox(QMessageBox::Icon::Warning, "Import nicht möglich", err.what(), QMessageBox::Ok,
+                    this)
+            .exec();
    }
-
    setSaleModel();
    updateStatLabel();
 }
@ -552,7 +550,7 @@ void MainWindow::readGeometry()
    settings.endGroup();
 }

-void MainWindow::closeEvent(QCloseEvent *event)
+void MainWindow::closeEvent(QCloseEvent* event)
 {
    writeGeometry();
    event->accept();
@ -562,9 +560,9 @@ void MainWindow::updateStatLabel()
 {
    std::string statistics("<b>KIMA2 - Version ");
    statistics += PROJECT_VERSION;
-    statistics += "</b><br />Verkäufer: " + std::to_string(m_marketplace->getSellers().size() - 1);
-    statistics += "<br />Kunden: " + std::to_string(m_marketplace->getSales().size());
-    statistics += "<br />Umsatz: " + m_marketplace->getOverallSumAsString();
+    statistics += "</b><br />Verkäufer: " + std::to_string(marketplace_->getSellers().size() - 1);
+    statistics += "<br />Kunden: " + std::to_string(marketplace_->getSales().size());
+    statistics += "<br />Umsatz: " + marketplace_->getOverallSumAsString();

-    m_ui.statLabel->setText(statistics.c_str());
+    ui_.statLabel->setText(statistics.c_str());
 }
--- a/src/gui/mainwindow.h
+++ b/src/gui/mainwindow.h
@ -3,7 +3,7 @@

 #include "ui_mainwindow.h"

-#include <core/marketplace.h>
+#include <marketplace.h>

 #include <QMainWindow>
 #include <QtGui/QCloseEvent>
@ -16,7 +16,7 @@ class MainWindow : public QMainWindow

  public:
    MainWindow();
-    Marketplace* getMarketplace() { return m_marketplace.get(); }
+    Marketplace* getMarketplace() { return marketplace_.get(); }

  private slots:
    void onBasketViewSelectionChanged(const QItemSelection& selected,
@ -29,7 +29,7 @@ class MainWindow : public QMainWindow
    void onCancelAllArticlesButtonClicked(bool checked);
    void onAboutQt();
    void onAbout();
-    virtual bool eventFilter(QObject* target, QEvent* event) override;
+    virtual bool eventFilter(QObject *target, QEvent *event) override;

  protected:
    virtual void closeEvent(QCloseEvent* event) override;
@ -39,7 +39,9 @@ class MainWindow : public QMainWindow
    void checkSellerNo(bool ctrlPressed = false);
    void onPaidButtonTriggered();
    void onGivenSpinBoxValueChanged(double value);
-    void onImportSellerActionTriggered();
+    void onImportSellerExcelActionTriggered();
+    void onImportSellerJsonActionTriggered();
+    void onExportSellerJsonActionTriggered();
    void onExportSalesJsonActionTriggered();
    void onImportSalesJsonActionTriggered();
    void setSaleModel();
@ -47,8 +49,8 @@ class MainWindow : public QMainWindow
    void readGeometry();
    void updateStatLabel();

-    Ui::MainWindow m_ui;
-    std::unique_ptr<Marketplace> m_marketplace;
+    Ui::MainWindow ui_;
+    std::unique_ptr<Marketplace> marketplace_;
 };

 #endif
--- a/src/gui/mainwindow.ui
+++ b/src/gui/mainwindow.ui
@ -112,11 +112,7 @@
            </widget>
           </item>
           <item>
-            <widget class="QDoubleSpinBox" name="givenSpinBox">
-             <property name="maximum">
-              <double>999.990000000000009</double>
-             </property>
-            </widget>
+            <widget class="QDoubleSpinBox" name="givenSpinBox"/>
           </item>
           <item>
            <widget class="QLabel" name="label_4">
@ -440,8 +436,16 @@ drucken</string>
    <property name="title">
     <string>&amp;Verkäufer</string>
    </property>
+    <widget class="QMenu" name="importSellerMenu">
+     <property name="title">
+      <string>Importieren</string>
+     </property>
+     <addaction name="importSellerExcelAction"/>
+     <addaction name="importSellerJsonAction"/>
+    </widget>
    <addaction name="actionEditSeller"/>
-    <addaction name="importSellerAction"/>
+    <addaction name="importSellerMenu"/>
+    <addaction name="exportSellerJsonAction"/>
   </widget>
   <widget class="QMenu" name="menuHilfe">
    <property name="title">
@ -505,9 +509,9 @@ drucken</string>
    <string>Exportieren für andere Kasse (JSON)</string>
   </property>
  </action>
-  <action name="importSellerActionX">
+  <action name="importSellerExcelAction">
   <property name="text">
-    <string>Aus CSV-Datei (initial)</string>
+    <string>Aus Excel-Datei (initial)</string>
   </property>
  </action>
  <action name="importSellerJsonAction">
@ -540,11 +544,6 @@ drucken</string>
    <string>Lizenz</string>
   </property>
  </action>
-  <action name="importSellerAction">
-   <property name="text">
-    <string>Importieren (aus CSV-Datei)</string>
-   </property>
-  </action>
 </widget>
 <resources/>
 <connections/>
--- a/src/gui/meson.build
+++ b/src/gui/meson.build
@ -1,23 +0,0 @@
-qt5 = import('qt5')
-qt5_dep = dependency('qt5', modules: ['Core', 'Gui', 'PrintSupport', 'Network'])
-
-thread_dep = dependency('threads')
-
-
-src = ['kima2.cpp', 'mainwindow.cpp',  'sellerdialog.cpp', 'sellermodel.cpp', 
-       'pricedialog.cpp', 'basketmodel.cpp', 'salemodel.cpp', 'reportdialog.cpp',
-       'reportmodel.cpp', 'settingsdialog.cpp']
-    
-ui = ['mainwindow.ui', 'sellerdialog.ui', 'pricedialog.ui', 'reportdialog.ui', 'settingsdialog.ui']
-
-processed = qt5.preprocess(moc_headers : ['basketmodel.h', 'mainwindow.h', 'pricedialog.h',
-                                          'reportdialog.h', 'sellerdialog.h', 'settingsdialog.h',
-                                          'sellermodel.h', 'salemodel.h'],
-                           ui_files : ui,
-                           qresources : '../../kima2.qrc',
-                           dependencies: qt5_dep)
-                           
-kima2 = executable('kima2', sources : [src, processed], 
-                   dependencies : [qt5_dep, singleapp_dep, core_dep, printer_dep, thread_dep],
-                   include_directories : [configuration_inc],
-		   install : true)
--- a/src/gui/pricedialog.cpp
+++ b/src/gui/pricedialog.cpp
@ -6,31 +6,34 @@

 PriceDialog::PriceDialog(QWidget* parent, bool forceDesc, Qt::WindowFlags f) : QDialog(parent, f)
 {
-    m_forceDesc = forceDesc;
-    m_ui.setupUi(this);
-    m_ui.priceSpinBox->setFocus();
+    forceDesc_ = forceDesc;
+    ui_.setupUi(this);
+    ui_.priceSpinBox->setFocus();
 }

-int PriceDialog::getPrice() const { return static_cast<int>(m_ui.priceSpinBox->value() * 100); }
+int PriceDialog::getPrice() const { return static_cast<int>(ui_.priceSpinBox->value() * 100); }

-std::string PriceDialog::getDescription() const { return m_ui.descEdit->text().toStdString(); }
+std::string PriceDialog::getDescription() const { return ui_.descEdit->text().toStdString(); }

 void PriceDialog::accept()
 {
-    if (static_cast<int>(std::round(m_ui.priceSpinBox->value() * 100.0L)) % 50 != 0) {
+    if (static_cast<int>(std::round(ui_.priceSpinBox->value() * 100.0L)) % 50 != 0) {
        QMessageBox(QMessageBox::Icon::Warning, "Falsche Preiseingabe",
                    "Es sind nur 0,50 Cent-Schritte erlaubt.", QMessageBox::StandardButton::Ok,
                    this)
            .exec();
-    } else if (m_forceDesc && m_ui.descEdit->text().trimmed().isEmpty()) {
+    } else if (forceDesc_ && ui_.descEdit->text().trimmed().isEmpty()) {
        QMessageBox(QMessageBox::Icon::Warning, "Artikelbeschreibung fehlt",
                    "Da Sie auf das Sonderkonto buchen ist eine Artikelbeschreibung erforderlich.",
                    QMessageBox::StandardButton::Ok, this)
            .exec();
-        m_ui.descEdit->setFocus();
+        ui_.descEdit->setFocus();
    } else {
        QDialog::accept();
    }
 }

-void PriceDialog::setForceDesc(bool force) { m_forceDesc = force; }
+void PriceDialog::setForceDesc(bool force)
+{
+    forceDesc_ = force;
+}
--- a/src/gui/pricedialog.h
+++ b/src/gui/pricedialog.h
@ -19,8 +19,8 @@ class PriceDialog : public QDialog
  private:
    void on_model_duplicateSellerNo(const QString& message);
    virtual void accept() override;
-    Ui::PriceDialog m_ui;
-    bool m_forceDesc;
+    Ui::PriceDialog ui_;
+    bool forceDesc_;
 };

 #endif
--- a/src/gui/pricedialog.ui
+++ b/src/gui/pricedialog.ui
@ -6,8 +6,8 @@
   <rect>
    <x>0</x>
    <y>0</y>
-    <width>266</width>
-    <height>128</height>
+    <width>201</width>
+    <height>127</height>
   </rect>
  </property>
  <property name="windowTitle">
@ -18,11 +18,6 @@
    <layout class="QGridLayout" name="gridLayout">
     <item row="0" column="0">
      <widget class="QLabel" name="label">
-       <property name="font">
-        <font>
-         <pointsize>16</pointsize>
-        </font>
-       </property>
       <property name="text">
        <string>Preis</string>
       </property>
@ -33,11 +28,6 @@
     </item>
     <item row="0" column="1">
      <widget class="QDoubleSpinBox" name="priceSpinBox">
-       <property name="font">
-        <font>
-         <pointsize>16</pointsize>
-        </font>
-       </property>
       <property name="minimum">
        <double>-999.990000000000009</double>
       </property>
@ -61,18 +51,6 @@
     </item>
     <item row="1" column="1">
      <widget class="QLineEdit" name="descEdit">
-       <property name="sizePolicy">
-        <sizepolicy hsizetype="MinimumExpanding" vsizetype="Fixed">
-         <horstretch>0</horstretch>
-         <verstretch>0</verstretch>
-        </sizepolicy>
-       </property>
-       <property name="minimumSize">
-        <size>
-         <width>200</width>
-         <height>0</height>
-        </size>
-       </property>
       <property name="placeholderText">
        <string>(optional)</string>
       </property>
--- a/src/gui/reportdialog.cpp
+++ b/src/gui/reportdialog.cpp
@ -2,9 +2,8 @@

 #include "mainwindow.h"

-#include <core/utils.h>
-#include <printer/posprinter.h>
-#include <printer/utils.h>
+#include <posprinter.h>
+#include <utils.h>

 #include <filesystem>

@ -17,22 +16,22 @@

 namespace fs = std::filesystem;

-ReportDialog::ReportDialog(QWidget *parent, Qt::WindowFlags f) : QDialog(parent, f)
+ReportDialog::ReportDialog(QWidget* parent, Qt::WindowFlags f) : QDialog(parent, f)
 {
-    m_ui.setupUi(this);
-    m_market = dynamic_cast<MainWindow *>(parent)->getMarketplace();
-    m_model = std::make_unique<ReportModel>(m_market, m_ui.reportView);
-    m_ui.reportView->setModel(m_model.get());
-    m_ui.reportView->hideColumn(0);
-    m_ui.reportView->setRowHidden(0, true); // hide the special "Sonderkonto" user
+    ui_.setupUi(this);
+    market_ = dynamic_cast<MainWindow*>(parent)->getMarketplace();
+    model_ = std::make_unique<ReportModel>(market_, ui_.reportView);
+    ui_.reportView->setModel(model_.get());
+    ui_.reportView->hideColumn(0);
+    ui_.reportView->setRowHidden(0, true); // hide the special "Sonderkonto" user

-    connect(m_ui.exportCsvButton, &QPushButton::clicked, this,
+    connect(ui_.exportCsvButton, &QPushButton::clicked, this,
            &ReportDialog::onExportCsvButtonClicked);
-    connect(m_ui.printReportButton, &QPushButton::clicked, this,
+    connect(ui_.printReportButton, &QPushButton::clicked, this,
            &ReportDialog::onPrintReportButtonClicked);
-    connect(m_ui.printSellerReceiptButton, &QPushButton::clicked, this,
+    connect(ui_.printSellerReceiptButton, &QPushButton::clicked, this,
            &ReportDialog::onPrintSellerReceiptButtonClicked);
-    connect(m_ui.reportView->selectionModel(), &QItemSelectionModel::selectionChanged, this,
+    connect(ui_.reportView->selectionModel(), &QItemSelectionModel::selectionChanged, this,
            &ReportDialog::onReportViewSelectionChanged);
 }

@ -48,13 +47,9 @@ void ReportDialog::onExportCsvButtonClicked()
    if (filename.isEmpty())
        return;

-#if defined(_WIN64) || defined(_WIN32)
    fs::path filePath(filename.toStdWString());
-#else
-    fs::path filePath(filename.toStdString());
-#endif

-    m_market->exportReportToCSV(filePath, feeInPercent, maxFeeInEuro);
+    market_->exportReportToCSV(filePath, feeInPercent, maxFeeInEuro);
 }

 void ReportDialog::onPrintReportButtonClicked()
@ -75,8 +70,8 @@ void ReportDialog::onPrintReportButtonClicked()
    QPainter painter;
    int height = printer.height();
    int width = printer.width();
-    const double ENTRIES_PER_PAGE = 45;
-    const auto &sellers = m_market->getSellers();
+    const double ENTRIES_PER_PAGE = 51;
+    const auto& sellers = market_->getSellers();
    unsigned int numPages = std::ceil(sellers.size() / ENTRIES_PER_PAGE);

    painter.begin(&printer);
@ -107,7 +102,7 @@ void ReportDialog::onPrintReportButtonClicked()
        for (unsigned int j = 0;
             j < ENTRIES_PER_PAGE && (i - 1) * ENTRIES_PER_PAGE + j < sellers.size(); ++j) {
            int idx = (i - 1) * ENTRIES_PER_PAGE + j;
-            if (sellers.at(idx)->getId() == 0) {
+            if (sellers.at(idx)->getUuidAsString() == "11111111-1111-1111-1111-111111111111") {
                continue;
            }
            content += QString("%1 %2 %3 %4 %5 %6 %7\n")
@ -126,7 +121,7 @@ void ReportDialog::onPrintReportButtonClicked()
    }

    // pieces booked on the special account "Sonderkonto"
-    const auto specialSeller = m_market->findSellerWithSellerNo(0);
+    const auto specialSeller = market_->findSellerWithUuid("11111111-1111-1111-1111-111111111111");
    if (specialSeller && specialSeller->numArticlesSold() > 0) {
        printer.newPage();
        painter.setFont(QFont("Arial", 16, QFont::Bold));
@ -136,7 +131,7 @@ void ReportDialog::onPrintReportButtonClicked()
        QString content("Einzelteile ohne Nummer\n=======================\n\n");
        unsigned int lines{0};
        unsigned int pages{1};
-        for (const auto &article : specialSeller->getArticles(true)) {
+        for (const auto& article : specialSeller->getArticles(true)) {
            content += QString("- %1:").arg(article->getDescription().substr(0, 45).c_str(), -45);
            content += QString("%1\n").arg(article->getPriceAsString().c_str(), 11);
            ++lines;
@ -163,8 +158,8 @@ void ReportDialog::onPrintReportButtonClicked()
                     "Auswertung Kindersachenmarkt");
    painter.setFont(fixedFont);
    QString content("Gesamtstatistik\n===============\n\n");
-    int numArticlesOffered = m_market->getNumArticlesOffered();
-    int numArticlesSold = m_market->getNumArticlesSold();
+    int numArticlesOffered = market_->getNumArticlesOffered();
+    int numArticlesSold = market_->getNumArticlesSold();
    double percentArticlesSold =
        (static_cast<double>(numArticlesSold) / static_cast<double>(numArticlesOffered)) * 100;
    content += QString("Registrierte Verkäufer: %1\n").arg(sellers.size() - 1, 6);
@ -172,14 +167,14 @@ void ReportDialog::onPrintReportButtonClicked()
    content += QString("Verkaufte Artikel:      %1 (%L2 %)\n")
                   .arg(numArticlesSold, 6)
                   .arg(percentArticlesSold, 0, 'f', 2);
-    content += QString("Anzahl Kunden:          %1\n\n").arg(m_market->getSales().size(), 6);
-    content += QString("Gesamtumsatz:     %1\n").arg(m_market->getOverallSumAsString().c_str(), 10);
+    content += QString("Anzahl Kunden:          %1\n\n").arg(market_->getSales().size(), 6);
+    content += QString("Gesamtumsatz:     %1\n").arg(market_->getOverallSumAsString().c_str(), 10);
    content +=
        QString("Ausgezahlt:       %1\n")
-            .arg(m_market->getOverallPaymentAsString(feeInPercent, maxFeeInEuro * 100).c_str(), 10);
+            .arg(market_->getOverallPaymentAsString(feeInPercent, maxFeeInEuro * 100).c_str(), 10);
    content +=
        QString("Verbleibend:      %1\n\n")
-            .arg(m_market->getOverallRevenueAsString(feeInPercent, maxFeeInEuro * 100).c_str(), 10);
+            .arg(market_->getOverallRevenueAsString(feeInPercent, maxFeeInEuro * 100).c_str(), 10);
    content += QString("(Einbehaltener Prozentsatz:    %1 %)\n").arg(feeInPercent, 3);
    content += QString("(Maximal einbehaltener Betrag: %1 €)\n").arg(maxFeeInEuro, 3);

@ -196,12 +191,12 @@ void ReportDialog::onPrintSellerReceiptButtonClicked()
    QString posPrinterDevice = settings.value("global/posPrinterDevice", "").toString();
    QString posPrinterEndpoint = settings.value("global/posPrinterEndpoint", "").toString();

-    auto selModel = m_ui.reportView->selectionModel();
+    auto selModel = ui_.reportView->selectionModel();
    if (selModel->hasSelection() == false)
        return;

    auto indexes = selModel->selectedRows();
-    auto &seller = m_market->getSellers().at(indexes[0].row());
+    auto& seller = market_->getSellers().at(indexes[0].row());

    auto printerDevice =
        convertToPosPrinterDevice(posPrinterDevice.toStdString(), posPrinterEndpoint.toStdString());
@ -220,12 +215,12 @@ void ReportDialog::onPrintSellerReceiptButtonClicked()
            settings.value("global/commune", "Dettingen").toString().toStdString());
 }

-void ReportDialog::onReportViewSelectionChanged(const QItemSelection &selected,
-                                                [[maybe_unused]] const QItemSelection &deselected)
+void ReportDialog::onReportViewSelectionChanged(const QItemSelection& selected,
+                                                [[maybe_unused]] const QItemSelection& deselected)
 {
    if (selected.size() > 0) {
-        m_ui.printSellerReceiptButton->setEnabled(true);
+        ui_.printSellerReceiptButton->setEnabled(true);
    } else {
-        m_ui.printSellerReceiptButton->setEnabled(false);
+        ui_.printSellerReceiptButton->setEnabled(false);
    }
 }
--- a/src/gui/reportdialog.h
+++ b/src/gui/reportdialog.h
@ -5,7 +5,7 @@

 #include "reportmodel.h"

-#include <core/marketplace.h>
+#include <marketplace.h>

 #include <QDialog>

@ -24,10 +24,9 @@ class ReportDialog : public QDialog
    void onReportViewSelectionChanged(const QItemSelection& selected,
                                      const QItemSelection& deselected);

-  private:
-    Ui::ReportDialog m_ui;
-    Marketplace* m_market;
-    std::unique_ptr<ReportModel> m_model;
+        private : Ui::ReportDialog ui_;
+    Marketplace* market_;
+    std::unique_ptr<ReportModel> model_;
 };

 #endif
--- a/src/gui/reportmodel.cpp
+++ b/src/gui/reportmodel.cpp
@ -5,16 +5,16 @@
 #include <QSettings>

 ReportModel::ReportModel(Marketplace* market, QObject* parent)
-    : QAbstractTableModel(parent), m_market(market)
+    : QAbstractTableModel(parent), market_(market)
 {
    QSettings settings;
-    m_feeInPercent = settings.value("global/feeInPercent").toInt();
-    m_maxFeeInCent = settings.value("global/maxFeeInEuro").toInt() * 100;
+    feeInPercent_ = settings.value("global/feeInPercent").toInt();
+    maxFeeInCent_ = settings.value("global/maxFeeInEuro").toInt() * 100;
 }

 int ReportModel::rowCount([[maybe_unused]] const QModelIndex& parent) const
 {
-    return static_cast<int>(m_market->getSellers().size());
+    return static_cast<int>(market_->getSellers().size());
 }

 int ReportModel::columnCount([[maybe_unused]] const QModelIndex& parent) const { return 7; }
@ -52,14 +52,14 @@ QVariant ReportModel::data(const QModelIndex& index, int role) const
    if (role != Qt::DisplayRole)
        return QVariant();

-    if (m_market->getSellers().size() == 0)
+    if (market_->getSellers().size() == 0)
        return QVariant();

-    Seller* seller = m_market->getSellers().at(index.row()).get();
+    Seller* seller = market_->getSellers().at(index.row()).get();

    switch (index.column()) {
    case 0:
-        return seller->getId();
+        return seller->getUuidAsString().c_str();
    case 1:
        return seller->getSellerNo();
    case 2:
@ -71,7 +71,7 @@ QVariant ReportModel::data(const QModelIndex& index, int role) const
    case 5:
        return seller->sumAsString().c_str();
    case 6:
-        return paymentAsString(seller->sumInCents(), m_feeInPercent, m_maxFeeInCent).c_str();
+        return paymentAsString(seller->sumInCents(), feeInPercent_, maxFeeInCent_).c_str();
    default:
        return "???";
    }
--- a/src/gui/reportmodel.h
+++ b/src/gui/reportmodel.h
@ -1,7 +1,7 @@
 #ifndef REPORT_MODEL_H
 #define REPORT_MODEL_H

-#include <core/marketplace.h>
+#include <marketplace.h>

 #include <QAbstractTableModel>

@ -15,9 +15,9 @@ class ReportModel : public QAbstractTableModel
    virtual QVariant headerData(int section, Qt::Orientation orientation, int role) const override;

  private:
-    Marketplace* m_market;
-    int m_feeInPercent{};
-    int m_maxFeeInCent{};
+    Marketplace* market_;
+    int feeInPercent_{};
+    int maxFeeInCent_{};
 };

 #endif
--- a/src/gui/salemodel.cpp
+++ b/src/gui/salemodel.cpp
@ -1,6 +1,6 @@
 #include "salemodel.h"

-#include <core/article.h>
+#include <article.h>

 #include <algorithm>

@ -9,7 +9,7 @@

 SaleModel::SaleModel(Marketplace* market, QObject* parent) : QAbstractItemModel(parent)
 {
-    m_marketplace = market;
+    marketplace_ = market;
 }

 QModelIndex SaleModel::index(int row, int column, const QModelIndex& parent) const
@ -18,7 +18,7 @@ QModelIndex SaleModel::index(int row, int column, const QModelIndex& parent) con
        return QModelIndex();

    if (!parent.isValid()) {
-        Sale* sale = m_marketplace->getSales().at(row).get();
+        Sale* sale = marketplace_->getSales().at(row).get();
        return createIndex(row, column, sale);
    } else if (!parent.parent().isValid()) {
        Sale* sale = static_cast<Sale*>(parent.internalPointer());
@ -44,15 +44,15 @@ QModelIndex SaleModel::parent(const QModelIndex& index) const
    Sale* sale{};
    Article* article{};

-    EntityUuid* ent = static_cast<EntityUuid*>(index.internalPointer());
+    Entity* ent = static_cast<Entity*>(index.internalPointer());

    sale = dynamic_cast<Sale*>(ent);

    if (sale) {
-        if (sale == m_rootItem.get())
+        if (sale == rootItem.get())
            return QModelIndex();
        else {
-            return createIndex(-1, 0, m_rootItem.get());
+            return createIndex(-1, 0, rootItem.get());
        }
    } else {
        article = dynamic_cast<Article*>(ent);
@ -80,7 +80,7 @@ QVariant SaleModel::data(const QModelIndex& index, int role) const
    if (role == Qt::FontRole) {
        QFont myFont;
        QFont myFixedFont = QFontDatabase::systemFont(QFontDatabase::FixedFont);
-        if (myFixedFont.fixedPitch() == false) {
+	if (myFixedFont.fixedPitch() == false) {
            myFixedFont.setFamily("monospace");
        }

@ -113,9 +113,7 @@ QVariant SaleModel::data(const QModelIndex& index, int role) const
        Article* article = static_cast<Article*>(index.internalPointer());
        switch (index.column()) {
        case 0:
-            return (std::string("Verk. ") + article->getSeller()->getSellerNoAsString() + " (" +
-                    article->getCompleteArticleNo() + ")")
-                .c_str();
+            return (std::string("Verk. ") + article->getSeller()->getSellerNoAsString() + " (" + article->getCompleteArticleNo() + ")").c_str();
        case 1:
            return article->getPriceAsString().c_str();
        case 2:
@ -132,7 +130,7 @@ int SaleModel::rowCount(const QModelIndex& parent) const
        return 0;

    if (!parent.isValid()) {
-        return m_marketplace->getSales().size();
+        return marketplace_->getSales().size();
    } else if (!parent.parent().isValid()) {
        Sale* sale = static_cast<Sale*>(parent.internalPointer());
        return sale->getArticles().size();
@ -167,7 +165,7 @@ QVariant SaleModel::headerData(int section, Qt::Orientation orientation, int rol
 void SaleModel::onBasketDataChanged()
 {
    emit beginResetModel();
-    auto& sales = m_marketplace->getSales();
+    auto& sales = marketplace_->getSales();
    std::sort(sales.begin(), sales.end(), [](const auto& lhs, const auto& rhs) {
        return lhs->getTimestamp() > rhs->getTimestamp();
    });
@ -179,11 +177,11 @@ bool SaleModel::removeRows(int row, int count, const QModelIndex& parent)
    if (!parent.isValid()) {
        // remove complete sale
        emit beginRemoveRows(parent, row, row + count - 1);
-        auto& sale = m_marketplace->getSales().at(row);
+        auto& sale = marketplace_->getSales().at(row);
        sale->setState(Sale::State::DELETE);
        std::for_each(sale->getArticles().begin(), sale->getArticles().end(),
                      [](auto& a) { a->setState(Article::State::DELETE); });
-        m_marketplace->storeToDb();
+        marketplace_->storeToDb();
        emit endRemoveRows();

    } else if (!parent.parent().isValid()) {
@ -199,7 +197,7 @@ bool SaleModel::removeRows(int row, int count, const QModelIndex& parent)
            sale->setState(Sale::State::DELETE);
        }
        emit beginRemoveRows(parent.parent(), 0, 0);
-        m_marketplace->storeToDb();
+        marketplace_->storeToDb();
        emit endRemoveRows();
    }

--- a/src/gui/salemodel.h
+++ b/src/gui/salemodel.h
@ -1,7 +1,7 @@
 #ifndef SALEMODEL_H
 #define SALEMODEL_H

-#include <core/marketplace.h>
+#include <marketplace.h>

 #include <QAbstractItemModel>

@ -12,7 +12,7 @@ class SaleModel : public QAbstractItemModel
  public:
    explicit SaleModel(Marketplace* market, QObject* parent = nullptr);
    virtual QModelIndex index(int row, int column,
-                              const QModelIndex& parent = QModelIndex()) const override;
+                      const QModelIndex& parent = QModelIndex()) const override;
    virtual QModelIndex parent(const QModelIndex& index) const override;
    virtual QVariant data(const QModelIndex& index, int role) const override;
    virtual int rowCount(const QModelIndex& parent) const override;
@ -24,8 +24,8 @@ class SaleModel : public QAbstractItemModel
    void onBasketDataChanged();

  private:
-    Marketplace* m_marketplace;
-    std::unique_ptr<Sale> m_rootItem{new Sale()};
+    Marketplace* marketplace_;
+    std::unique_ptr<Sale> rootItem{new Sale()};
 };

 #endif
--- a/src/gui/sellerdialog.cpp
+++ b/src/gui/sellerdialog.cpp
@ -7,25 +7,25 @@

 SellerDialog::SellerDialog(QWidget* parent, Qt::WindowFlags f) : QDialog(parent, f)
 {
-    m_ui.setupUi(this);
-    m_ui.editButton->setVisible(false);
-    m_market = dynamic_cast<MainWindow*>(parent)->getMarketplace();
-    m_model = std::make_unique<SellerModel>(m_market, m_ui.tableView);
-    m_ui.tableView->setModel(m_model.get());
-    m_ui.tableView->setColumnHidden(0, true); // hide the uuid
-    m_ui.tableView->setRowHidden(0, true);    // hide the special "Sonderkonto" user
-    connect(m_ui.newButton, &QPushButton::clicked, this, &SellerDialog::on_newButton_clicked);
-    connect(m_ui.deleteButton, &QPushButton::clicked, this, &SellerDialog::on_deleteButton_clicked);
-    connect(m_model.get(), &SellerModel::duplicateSellerNo, this,
+    ui_.setupUi(this);
+    ui_.editButton->setVisible(false);
+    market_ = dynamic_cast<MainWindow*>(parent)->getMarketplace();
+    model_ = std::make_unique<SellerModel>(market_, ui_.tableView);
+    ui_.tableView->setModel(model_.get());
+    ui_.tableView->setColumnHidden(0, true); // hide the uuid
+    ui_.tableView->setRowHidden(0, true);    // hide the special "Sonderkonto" user
+    connect(ui_.newButton, &QPushButton::clicked, this, &SellerDialog::on_newButton_clicked);
+    connect(ui_.deleteButton, &QPushButton::clicked, this, &SellerDialog::on_deleteButton_clicked);
+    connect(model_.get(), &SellerModel::duplicateSellerNo, this,
            &SellerDialog::on_model_duplicateSellerNo);
-    connect(m_ui.tableView->selectionModel(), &QItemSelectionModel::selectionChanged, this,
+    connect(ui_.tableView->selectionModel(), &QItemSelectionModel::selectionChanged, this,
            &SellerDialog::onSellerViewSelectionChanged);
 }

 void SellerDialog::on_newButton_clicked()
 {
    // Don't allow new seller if market has already started
-    if (m_market->getSales().size() > 0) {
+    if (market_->getSales().size() > 0) {
        QMessageBox(QMessageBox::Icon::Warning, "Hinweis",
                    "Da die Verkaufsphase schon begonnen hat (Artikel wurden bereits verkauft) "
                    "können Sie keine Verkäufer mehr hinzufügen.",
@ -34,22 +34,22 @@ void SellerDialog::on_newButton_clicked()
        return;
    }

-    m_ui.tableView->reset();
-    m_ui.tableView->model()->insertRows(m_ui.tableView->model()->rowCount(), 1);
-    m_ui.tableView->scrollToBottom();
-    m_ui.tableView->selectRow(m_ui.tableView->model()->rowCount() - 1);
-    QModelIndex idx = m_ui.tableView->model()->index(m_ui.tableView->model()->rowCount() - 1, 2);
-    m_ui.tableView->setCurrentIndex(idx);
-    m_ui.tableView->edit(idx);
+    ui_.tableView->reset();
+    ui_.tableView->model()->insertRows(ui_.tableView->model()->rowCount(), 1);
+    ui_.tableView->scrollToBottom();
+    ui_.tableView->selectRow(ui_.tableView->model()->rowCount() - 1);
+    QModelIndex idx = ui_.tableView->model()->index(ui_.tableView->model()->rowCount() - 1, 2);
+    ui_.tableView->setCurrentIndex(idx);
+    ui_.tableView->edit(idx);
 }

 void SellerDialog::on_deleteButton_clicked()
 {
-    auto selModel = m_ui.tableView->selectionModel();
+    auto selModel = ui_.tableView->selectionModel();
    if (selModel->hasSelection() == false)
        return;

-    if (m_market->getSales().size() > 0) {
+    if (market_->getSales().size() > 0) {
        QMessageBox(QMessageBox::Icon::Warning, "Hinweis",
                    "Da die Verkaufsphase schon begonnen hat (Artikel wurden bereits verkauft) "
                    "können Sie keine Verkäufer mehr löschen.",
@ -60,8 +60,7 @@ void SellerDialog::on_deleteButton_clicked()

    auto dlgResult =
        QMessageBox(QMessageBox::Icon::Warning, "Sind Sie sicher?",
-                    "Löschen wirkt sich <b>sofort</b> auf die Datenbank aus. Sie können den "
-                    "Vorgang nicht rückgängig machen. Möchten Sie fortfahren?",
+                    "Löschen wirkt sich direkt auf die Datenbank aus. Möchten Sie fortfahren?",
                    QMessageBox::StandardButton::Yes | QMessageBox::StandardButton::No, this)
            .exec();
    if (dlgResult == QMessageBox::No)
@ -72,7 +71,7 @@ void SellerDialog::on_deleteButton_clicked()

    // Deleting the rows, beginning with the last one!
    for (auto iter = indexes.constEnd() - 1; iter >= indexes.constBegin(); --iter) {
-        m_ui.tableView->model()->removeRow(iter->row());
+        ui_.tableView->model()->removeRow(iter->row());
    }
 }

@ -102,8 +101,8 @@ void SellerDialog::onSellerViewSelectionChanged(const QItemSelection& selected,
                                                [[maybe_unused]] const QItemSelection& deselected)
 {
    if (selected.size() > 0) {
-        m_ui.deleteButton->setEnabled(true);
+        ui_.deleteButton->setEnabled(true);
    } else {
-        m_ui.deleteButton->setEnabled(false);
+        ui_.deleteButton->setEnabled(false);
    }
 }
--- a/src/gui/sellerdialog.h
+++ b/src/gui/sellerdialog.h
@ -26,9 +26,9 @@ class SellerDialog : public QDialog
    void on_deleteButton_clicked();
    void on_model_duplicateSellerNo(const QString& message);
    virtual void accept() override;
-    Ui::SellerDialog m_ui;
-    Marketplace* m_market;
-    std::unique_ptr<SellerModel> m_model;
+    Ui::SellerDialog ui_;
+    Marketplace* market_;
+    std::unique_ptr<SellerModel> model_;
 };

 #endif
--- a/src/gui/sellermodel.cpp
+++ b/src/gui/sellermodel.cpp
@ -5,13 +5,13 @@
 #include <QMessageBox>

 SellerModel::SellerModel(Marketplace* market, QObject* parent)
-    : QAbstractTableModel(parent), m_marketplace(market)
+    : QAbstractTableModel(parent), marketplace_(market)
 {
 }

 int SellerModel::rowCount([[maybe_unused]] const QModelIndex& parent) const
 {
-    return m_marketplace->getSellers().size();
+    return marketplace_->getSellers().size();
 }

 int SellerModel::columnCount([[maybe_unused]] const QModelIndex& parent) const { return 5; }
@ -21,14 +21,17 @@ QVariant SellerModel::data(const QModelIndex& index, int role) const
    if (role != Qt::DisplayRole)
        return QVariant();

-    if (m_marketplace->getSellers().size() == 0)
+    if (marketplace_->getSellers().size() == 0)
        return QVariant();

-    Seller* seller = m_marketplace->getSellers().at(index.row()).get();
+    Seller* seller = marketplace_->getSellers().at(index.row()).get();

+    /*      if (seller->getState() == Seller::State::DELETE)
+            return QVariant();
+     */
    switch (index.column()) {
    case 0:
-        return seller->getId();
+        return seller->getUuidAsString().c_str();
    case 1:
        return seller->getSellerNo();
    case 2:
@ -78,21 +81,21 @@ bool SellerModel::setData(const QModelIndex& index, const QVariant& value, int r
    if (role != Qt::EditRole)
        return false;

-    Seller* seller = m_marketplace->getSellers().at(index.row()).get();
+    Seller* seller = marketplace_->getSellers().at(index.row()).get();

    switch (index.column()) {
    case 0:
-        seller->setId(value.toInt());
+        seller->setUuidFromString(value.toString().toStdString());
        break;
    case 1: {
        if (value.toInt() < 0)
            return false;
        auto iter =
-            std::find_if(m_marketplace->getSellers().begin(), m_marketplace->getSellers().end(),
+            std::find_if(marketplace_->getSellers().begin(), marketplace_->getSellers().end(),
                         [&value](const std::unique_ptr<Seller>& s) {
                             return value.toInt() == s->getSellerNo();
                         });
-        if (iter != m_marketplace->getSellers().end()) {
+        if (iter != marketplace_->getSellers().end()) {
            emit duplicateSellerNo(
                "Die Verkäufernummer muss eindeutig sein.\n(Möglicherweise wird die Nummer von "
                "einem (ausgeblendeten) Eintrag, der zum Löschen vorgemerkt ist, verwendet.)");
@ -123,8 +126,9 @@ bool SellerModel::insertRows(int row, int count, const QModelIndex& parent)
 {
    emit beginInsertRows(parent, row, row + count - 1);
    auto seller = std::make_unique<Seller>();
-    seller->setSellerNo(m_marketplace->getNextSellerNo());
-    m_marketplace->getSellers().push_back(std::move(seller));
+    seller->createUuid();
+    seller->setSellerNo(marketplace_->getNextSellerNo());
+    marketplace_->getSellers().push_back(std::move(seller));
    emit endInsertRows();

    return true;
@ -132,21 +136,21 @@ bool SellerModel::insertRows(int row, int count, const QModelIndex& parent)

 bool SellerModel::removeRows(int row, int count, const QModelIndex& parent)
 {
-    auto seller = m_marketplace->getSellers().at(row).get();
+    auto seller = marketplace_->getSellers().at(row).get();
    if (seller->getState() == Seller::State::NEW) {
        emit beginRemoveRows(parent, row, row + count - 1);
-        m_marketplace->getSellers().erase(
-            std::remove_if(m_marketplace->getSellers().begin(), m_marketplace->getSellers().end(),
+        marketplace_->getSellers().erase(
+            std::remove_if(marketplace_->getSellers().begin(), marketplace_->getSellers().end(),
                           [&seller](const std::unique_ptr<Seller>& a) {
-                               return a->getId() == seller->getId();
+                               return a->getUuid() == seller->getUuid();
                           }),
-            m_marketplace->getSellers().end());
+            marketplace_->getSellers().end());
        emit endRemoveRows();
        return true;
    } else {
        emit beginRemoveRows(parent, row, row + count - 1);
        seller->setState(Seller::State::DELETE);
-        m_marketplace->storeToDb(true);
+        marketplace_->storeToDb(true);
        emit endRemoveRows();
        return true;
    }
--- a/src/gui/sellermodel.h
+++ b/src/gui/sellermodel.h
@ -1,31 +1,30 @@
 #ifndef SELLER_MODEL_H
 #define SELLER_MODEL_H

-#include <core/marketplace.h>
+#include <marketplace.h>

 #include <QAbstractTableModel>

 class SellerModel : public QAbstractTableModel
 {
-    Q_OBJECT
+  Q_OBJECT

-public:
-    explicit SellerModel(Marketplace *market, QObject *parent = nullptr);
-    virtual int rowCount(const QModelIndex &parent = QModelIndex()) const override;
-    virtual int columnCount(const QModelIndex &parent = QModelIndex()) const override;
-    virtual QVariant data(const QModelIndex &index, int role = Qt::DisplayRole) const override;
+  public:
+    explicit SellerModel(Marketplace* market, QObject* parent = nullptr);
+    virtual int rowCount(const QModelIndex& parent = QModelIndex()) const override;
+    virtual int columnCount(const QModelIndex& parent = QModelIndex()) const override;
+    virtual QVariant data(const QModelIndex& index, int role = Qt::DisplayRole) const override;
    virtual QVariant headerData(int section, Qt::Orientation orientation, int role) const override;
-    virtual Qt::ItemFlags flags(const QModelIndex &index) const override;
-    virtual bool setData(const QModelIndex &index, const QVariant &value,
-                         int role = Qt::EditRole) override;
-    virtual bool insertRows(int row, int count, const QModelIndex &parent = QModelIndex()) override;
-    virtual bool removeRows(int row, int count, const QModelIndex &parent = QModelIndex()) override;
+    virtual Qt::ItemFlags flags(const QModelIndex& index) const override;
+    virtual bool setData(const QModelIndex& index, const QVariant& value, int role = Qt::EditRole) override;
+    virtual bool insertRows(int row, int count, const QModelIndex& parent = QModelIndex()) override;
+    virtual bool removeRows(int row, int count, const QModelIndex& parent = QModelIndex()) override;

-signals:
-    void duplicateSellerNo(const QString &message);
+  signals:
+    void duplicateSellerNo(const QString& message);

-private:
-    Marketplace *m_marketplace;
+  private:
+    Marketplace* marketplace_;
 };

 #endif
--- a/src/gui/settingsdialog.cpp
+++ b/src/gui/settingsdialog.cpp
@ -2,10 +2,9 @@

 #include "mainwindow.h"

-#include <core/database.h>
-#include <core/utils.h>
-#include <printer/posprinter.h>
-#include <printer/utils.h>
+#include <database.h>
+#include <posprinter.h>
+#include <utils.h>

 #include <exception>
 #include <stdexcept>
@ -13,9 +12,9 @@
 #include <QMessageBox>
 #include <QSettings>

-SettingsDialog::SettingsDialog(QWidget *parent, Qt::WindowFlags f) : QDialog(parent, f)
+SettingsDialog::SettingsDialog(QWidget* parent, Qt::WindowFlags f) : QDialog(parent, f)
 {
-    m_ui.setupUi(this);
+    ui_.setupUi(this);

    QSettings settings{};
    int cashPointNo = settings.value("global/cashPointNo").toInt();
@ -26,25 +25,25 @@ SettingsDialog::SettingsDialog(QWidget *parent, Qt::WindowFlags f) : QDialog(par
    int maxFeeInEuro = settings.value("global/maxFeeInEuro").toInt();

    if (parent)
-        m_market = dynamic_cast<MainWindow *>(parent)->getMarketplace();
+        market_ = dynamic_cast<MainWindow*>(parent)->getMarketplace();

-    m_ui.cashPointNoSpinBox->setValue(cashPointNo);
-    m_ui.communeEdit->setText(commune);
-    m_ui.posPrinterDeviceEdit->setText(posPrinterDevice);
-    m_ui.posPrinterEndpointEdit->setText(posPrinterEndpoint);
-    m_ui.feePercentSpinBox->setValue(feeInPercent);
-    m_ui.maxFeeSpinBox->setValue(maxFeeInEuro);
+    ui_.cashPointNoSpinBox->setValue(cashPointNo);
+    ui_.communeEdit->setText(commune);
+    ui_.posPrinterDeviceEdit->setText(posPrinterDevice);
+    ui_.posPrinterEndpointEdit->setText(posPrinterEndpoint);
+    ui_.feePercentSpinBox->setValue(feeInPercent);
+    ui_.maxFeeSpinBox->setValue(maxFeeInEuro);

-    connect(m_ui.testPosPrinterButton, &QPushButton::clicked, this, [this]() {
+    connect(ui_.testPosPrinterButton, &QPushButton::clicked, this, [=]() {
        using namespace std::string_literals;
        try {
-            if (m_ui.posPrinterDeviceEdit->text().isEmpty()) {
+            if (ui_.posPrinterDeviceEdit->text().isEmpty()) {
                PosPrinter printer;
                printer.printTest();
            } else {
-                std::string posPrinterDeviceString = m_ui.posPrinterDeviceEdit->text().toStdString();
+                std::string posPrinterDeviceString = ui_.posPrinterDeviceEdit->text().toStdString();
                std::string posPrinterEndpointString =
-                    m_ui.posPrinterEndpointEdit->text().toStdString();
+                    ui_.posPrinterEndpointEdit->text().toStdString();

                try {
                    auto printerDevice =
@ -55,7 +54,7 @@ SettingsDialog::SettingsDialog(QWidget *parent, Qt::WindowFlags f) : QDialog(par
                        printer.printTest();
                    }

-                } catch (std::exception &) {
+                } catch (std::exception&) {
                    QMessageBox(QMessageBox::Icon::Warning, "Falsche Eingabe",
                                QString("Eingabeformat für Device (hexadezimale IDs): "
                                        "<VendorID>:<ProductID>\nBeispiel: 0416:5011\n "
@ -65,7 +64,7 @@ SettingsDialog::SettingsDialog(QWidget *parent, Qt::WindowFlags f) : QDialog(par
                    return;
                }
            }
-        } catch (std::runtime_error &err) {
+        } catch (std::runtime_error& err) {
            QMessageBox(QMessageBox::Icon::Warning, "Bondrucker Fehler",
                        QString("Test schlug fehl: ") + err.what(), QMessageBox::StandardButton::Ok,
                        this)
@ -80,17 +79,17 @@ void SettingsDialog::accept()
    QSettings settings;

    int oldCashPointNo = settings.value("global/cashPointNo").toInt();
-    int newCashPointNo = m_ui.cashPointNoSpinBox->value();
+    int newCashPointNo = ui_.cashPointNoSpinBox->value();

-    settings.setValue("global/commune", m_ui.communeEdit->text().trimmed());
-    settings.setValue("global/posPrinterDevice", m_ui.posPrinterDeviceEdit->text().trimmed());
-    settings.setValue("global/posPrinterEndpoint", m_ui.posPrinterEndpointEdit->text().trimmed());
-    settings.setValue("global/feeInPercent", m_ui.feePercentSpinBox->value());
-    settings.setValue("global/maxFeeInEuro", m_ui.maxFeeSpinBox->value());
+    settings.setValue("global/commune", ui_.communeEdit->text().trimmed());
+    settings.setValue("global/posPrinterDevice", ui_.posPrinterDeviceEdit->text().trimmed());
+    settings.setValue("global/posPrinterEndpoint", ui_.posPrinterEndpointEdit->text().trimmed());
+    settings.setValue("global/feeInPercent", ui_.feePercentSpinBox->value());
+    settings.setValue("global/maxFeeInEuro", ui_.maxFeeSpinBox->value());

    if (oldCashPointNo != newCashPointNo) {
        int result{0};
-        if (m_market && m_market->getSales().size() > 0) {
+        if (market_ && market_->getSales().size() > 0) {
            result = QMessageBox(QMessageBox::Icon::Question, "Sind Sie sicher?",
                                 "Möchten Sie die Kassen-Nr wirklich ändern? Diese muss über alle "
                                 "Installationen hinweg eindeutig sein.",
@ -103,7 +102,7 @@ void SettingsDialog::accept()
        if (result == QMessageBox::Yes) {
            try {
                Database().updateCashPointNo(oldCashPointNo, newCashPointNo);
-            } catch (std::exception &ex) {
+            } catch (std::exception& ex) {
                std::string errMsg("Das Ändern der Kassen-Nr. ist fehlgeschlagen: ");
                errMsg.append(ex.what());
                QMessageBox(QMessageBox::Icon::Critical, "Fehler", errMsg.c_str(),
@ -112,7 +111,7 @@ void SettingsDialog::accept()
                QDialog::accept();
                return;
            }
-            settings.setValue("global/cashPointNo", m_ui.cashPointNoSpinBox->value());
+            settings.setValue("global/cashPointNo", ui_.cashPointNoSpinBox->value());
        }
    }

--- a/src/gui/settingsdialog.h
+++ b/src/gui/settingsdialog.h
@ -3,14 +3,12 @@

 #include "ui_settingsdialog.h"

-#include <core/marketplace.h>
+#include <marketplace.h>

 #include <QDialog>

 class SettingsDialog : public QDialog
 {
-    Q_OBJECT
-    
  public:
    SettingsDialog(QWidget* parent = nullptr,
                   Qt::WindowFlags f = Qt::WindowTitleHint | Qt::WindowSystemMenuHint);
@ -19,8 +17,8 @@ class SettingsDialog : public QDialog
    void accept() override;

  private:
-    Ui::SettingsDialog m_ui;
-    Marketplace* m_market{};
+    Ui::SettingsDialog ui_;
+    Marketplace* market_{};
 };

 #endif
--- a/src/meson.build
+++ b/src/meson.build
@ -1,3 +0,0 @@
-subdir('core')
-subdir('printer')
-subdir('gui')
--- a/src/printer/CMakeLists.txt
+++ b/src/printer/CMakeLists.txt
@ -1,6 +1,6 @@
 set(Boost_USE_STATIC_LIBS ON)

-find_package(Boost 1.78 REQUIRED)
+find_package(Boost 1.62 REQUIRED)

 if(WIN32)
  find_package(LIBUSB REQUIRED)
@ -11,7 +11,6 @@ endif()

 set(PRINTER_SOURCES
    posprinter.cpp
-    utils.cpp
 )

 add_library(printer STATIC ${PRINTER_SOURCES})
@ -20,4 +19,4 @@ if(WIN32)
 else()
  target_link_libraries(printer core ${LibUSB_LIBRARIES})
 endif()
-target_include_directories(printer PUBLIC ${CMAKE_CURRENT_SOURCE_DIR}/.. ${Boost_INCLUDE_DIRS})
+target_include_directories(printer PUBLIC ${CMAKE_CURRENT_SOURCE_DIR})
--- a/src/printer/meson.build
+++ b/src/printer/meson.build
@ -1,9 +0,0 @@
-libusb = dependency('libusb-1.0')
-
-src = ['posprinter.cpp', 'utils.cpp']
-
-printer_inc = include_directories('..')
-
-printer_lib = static_library('printer', src, dependencies: [libusb, core_dep])
-
-printer_dep = declare_dependency(link_with : printer_lib, include_directories : printer_inc)
--- a/src/printer/posprinter.cpp
+++ b/src/printer/posprinter.cpp
@ -1,6 +1,6 @@
 #include "posprinter.h"

-#include <core/marketplace.h>
+#include <marketplace.h>

 #include <boost/date_time/posix_time/posix_time.hpp>

--- a/src/printer/posprinter.h
+++ b/src/printer/posprinter.h
@ -1,8 +1,8 @@
 #ifndef POS_PRINTER_H
 #define POS_PRINTER_H

-#include <core/sale.h>
-#include <core/seller.h>
+#include <sale.h>
+#include <seller.h>

 #include <memory>

@ -36,8 +36,7 @@ class PosPrinter
    void printHeader(const std::string& commune = "Musterhausen");
    void printTest();
    void printSaleReceipt(Sale* sale, const std::string& commune = "Dettingen");
-    void printSellerReceipt(Seller* seller, const int percent, const int maxFeeInCent,
-                            const std::string& commune = "Dettingen");
+    void printSellerReceipt(Seller* seller, const int percent, const int maxFeeInCent, const std::string& commune = "Dettingen");
    bool isValid();

    struct Command {
--- a/src/printer/utils.cpp
+++ b/src/printer/utils.cpp
@ -1,26 +0,0 @@
-#include "utils.h"
-
-std::optional<PrinterDevice> convertToPosPrinterDevice(const std::string& device,
-                                                       const std::string& endpoint)
-{
-    if (device.empty()) {
-        return std::nullopt;
-    }
-
-    PrinterDevice printerDevice;
-    std::string delimiter = ":";
-    try {
-        printerDevice.idVendor = std::stoi(device.substr(0, device.find(delimiter)), 0, 16);
-        printerDevice.idProduct = std::stoi(device.substr(device.find(delimiter) + 1), 0, 16);
-        if (endpoint.empty()) {
-            printerDevice.endpoint = 0x03;
-        } else {
-            printerDevice.endpoint = std::stoi(endpoint, 0, 16);
-        }
-
-    } catch (std::exception& ex) {
-        throw ex;
-    }
-
-    return printerDevice;
-}
--- a/src/printer/utils.h
+++ b/src/printer/utils.h
@ -1,12 +0,0 @@
-#ifndef PRINTER_UTILS_H
-#define PRINTER_UTILS_H
-
-#include "posprinter.h"
-
-#include <optional>
-#include <string>
-
-std::optional<PrinterDevice> convertToPosPrinterDevice(const std::string& vendor,
-                                                       const std::string& endpoint);
-
-#endif
--- a/subprojects/nlohmann_json
+++ b/subprojects/nlohmann_json
@ -1 +0,0 @@
-Subproject commit 9cca280a4d0ccf0c08f47a99aa71d1b0e52f8d03
--- a/subprojects/singleapplication/meson.build
+++ b/subprojects/singleapplication/meson.build
@ -1,27 +0,0 @@
-project('singleapplication')
-
-qt5 = import('qt5')
-dep_qt5 = dependency('qt5', modules: ['Core', 'Widgets', 'Network'])
-
-singleapp_inc = include_directories('singleapplication.git')
-
-singleapp_moc = qt5.preprocess(
-    moc_headers: ['singleapplication.git/singleapplication.h', 'singleapplication.git/singleapplication_p.h'],
-    moc_extra_arguments: ['-DQAPPLICATION_CLASS=QApplication'],
-    dependencies: dep_qt5
-)
-
-singleapp_lib = static_library('SingleApplication', 
-    ['singleapplication.git/singleapplication.cpp', 'singleapplication.git/singleapplication_p.cpp', singleapp_moc],
-    include_directories: singleapp_inc,
-    cpp_args : '-DQAPPLICATION_CLASS=QApplication',
-    dependencies: dep_qt5
-)
-
-singleapp_dep = declare_dependency(
-    include_directories: singleapp_inc,
-    link_with: singleapp_lib
-)
-
-# On windows, SingleApplication needs to be linked against advapi32. This is
-# done by adding 'advapi32' to cpp_winlibs, where it should be by default.
--- a/subprojects/singleapplication/singleapplication.git
+++ b/subprojects/singleapplication/singleapplication.git
@ -1 +0,0 @@
-Subproject commit 8c48163c4d3fbba603cfe8a5b94046c9dad71825
--- a/test/test_seller.cpp
+++ b/test/test_seller.cpp
@ -9,14 +9,14 @@
 BOOST_AUTO_TEST_CASE(create_uuid_nil)
 {
    Seller seller{};
-    BOOST_TEST(seller.getId().is_nil() == true);
+    BOOST_TEST(seller.getUuid().is_nil() == true);
 }

 BOOST_AUTO_TEST_CASE(create_uuid)
 {
    Seller seller{};
    seller.createUuid();
-    BOOST_TEST(seller.getId().is_nil() == false);
+    BOOST_TEST(seller.getUuid().is_nil() == false);
 }

 BOOST_AUTO_TEST_CASE(create_many)
@ -25,7 +25,7 @@ BOOST_AUTO_TEST_CASE(create_many)
    std::array<Seller, QUANTITY> sellers;
    for (unsigned i = 0; i < sellers.size(); i++) {
        sellers[i] = Seller();
-        //sellers[i].createUuid();
+        sellers[i].createUuid();
    }
 }
				`@ -0,0 +1 @@`
				`Subproject commit f1768a540a7b7c5cc30cdcd6be9e9ef91083719b`
				`@ -1 +0,0 @@`
				`Subproject commit 9cca280a4d0ccf0c08f47a99aa71d1b0e52f8d03`
				`@ -1 +0,0 @@`
				`Subproject commit 8c48163c4d3fbba603cfe8a5b94046c9dad71825`