added importing from csv

src/core/csvreader.cpp

@@ -0,0 +1,66 @@
+#include "csvreader.h"
+#include "utils.h"
+
+#include <fstream>
+#include <csv.hpp>
+
+namespace fs = std::filesystem;
+
+std::size_t CsvReader::readSellersFromFile(const fs::path& filePath, Marketplace* market)
+{
+    csv::CSVFormat format;
+    format.delimiter(';');
+
+    csv::CSVReader csvReader(filePath.string(), format);
+    
+    for (auto& seller : market->getSellers()) {
+        seller->setState(Seller::State::DELETE);
+    }
+
+    market->storeToDb(true);
+    
+    int rowCount{};
+    for (csv::CSVRow &row : csvReader) {
+        if (!row[0].is_int()) {
+            ++rowCount;
+            continue;
+        } 
+
+        if (row[2].get<std::string>().empty() && row[3].get<std::string>().empty()) {
+            ++rowCount;
+            continue;
+        }
+
+        auto seller = std::make_unique<Seller>();
+        seller->createUuid();
+        seller->setSellerNo(row[0].get<int>());
+        if (row[1].is_int()) {
+            seller->setNumArticlesOffered(row[1].get<int>());
+        } else {
+            seller->setNumArticlesOffered(0);
+        }
+        std::string firstName = row[2].get<std::string>();
+        seller->setFirstName(trim(firstName));
+        std::string lastName = row[3].get<std::string>();
+        seller->setLastName(trim(lastName));
+        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();
+
+    return market->getSellers().size() - 1; // minus 1 because we don't count the "special" seller
+}