#include "lcd.h"

// commands
constexpr int LCD_CLEARDISPLAY = 0x01;
constexpr int LCD_RETURNHOME = 0x02;
constexpr int LCD_ENTRYMODESET = 0x04;
constexpr int LCD_DISPLAYCONTROL = 0x08;
constexpr int LCD_CURSORSHIFT = 0x10;
constexpr int LCD_FUNCTIONSET = 0x20;
constexpr int LCD_SETCGRAMADDR = 0x40;
constexpr int LCD_SETDDRAMADDR = 0x80;

// flags for display entry mode
constexpr int LCD_ENTRYSHIFTINCREMENT = 0x01;
constexpr int LCD_ENTRYLEFT = 0x02;

// flags for display and cursor control
constexpr int LCD_BLINKON = 0x01;
constexpr int LCD_CURSORON = 0x02;
constexpr int LCD_DISPLAYON = 0x04;

// flags for function set
constexpr int LCD_5x10DOTS = 0x04;
constexpr int LCD_2LINE = 0x08;
constexpr int LCD_8BITMODE = 0x10;

constexpr int LCD_BACKLIGHT = 0x08;
constexpr int LCD_ENABLE_BIT = 0x04;

LCD::LCD(i2c_inst_t *i2c, const uint gpio_sda, const uint gpio_scl,
         const uint8_t i2c_addr, uint8_t num_cols, uint8_t num_lines)
    : i2c{i2c}, i2c_addr{i2c_addr}, num_cols{num_cols}, num_lines{num_lines} {
    i2c_init(i2c1, 100 * 1000);
    gpio_set_function(gpio_sda, GPIO_FUNC_I2C);
    gpio_set_function(gpio_scl, GPIO_FUNC_I2C);
    gpio_pull_up(gpio_sda);
    gpio_pull_up(gpio_scl);

    sendByte(0x03, Mode::COMMAND);
    sendByte(0x03, Mode::COMMAND);
    sendByte(0x03, Mode::COMMAND);
    sendByte(0x02, Mode::COMMAND);

    sendByte(LCD_ENTRYMODESET | LCD_ENTRYLEFT, Mode::COMMAND);
    sendByte(LCD_FUNCTIONSET | LCD_2LINE, Mode::COMMAND);
    sendByte(LCD_DISPLAYCONTROL | LCD_DISPLAYON, Mode::COMMAND);
    clear();
}

// go to location on LCD
void LCD::setCursor(int line, int position) {
    int val = (line == 0) ? 0x80 + position : 0xC0 + position;
    sendByte(val, Mode::COMMAND);
    cursor_x = line;
    cursor_y = position;
}

void LCD::sendChar(char val) { sendByte(val, Mode::CHARACTER); }

void LCD::sendString(const std::string &str) {
    for (const char &c : str) {
        if (c == '\n') {
            cursor_y++;
            setCursor(cursor_y, 0);
        } else {
            sendChar(c);
            cursor_x++;
        }
    }
}

void LCD::clear() { sendByte(LCD_CLEARDISPLAY, Mode::COMMAND); }

void LCD::i2cWriteByte(uint8_t val) {
    i2c_write_blocking(i2c, i2c_addr, &val, 1, false);
}

void LCD::toggleEnable(uint8_t val) {
    // Toggle enable pin on LCD display
    // We cannot do this too quickly or things don't work
    constexpr uint64_t DELAY_US = 600;
    sleep_us(DELAY_US);
    i2cWriteByte(val | LCD_ENABLE_BIT);
    sleep_us(DELAY_US);
    i2cWriteByte(val & ~LCD_ENABLE_BIT);
    sleep_us(DELAY_US);
}

// The display is sent a byte as two separate nibble transfers
void LCD::sendByte(uint8_t val, Mode mode) {
    uint8_t high = static_cast<int>(mode) | (val & 0xF0) | LCD_BACKLIGHT;
    uint8_t low = static_cast<int>(mode) | ((val << 4) & 0xF0) | LCD_BACKLIGHT;

    i2cWriteByte(high);
    toggleEnable(high);
    i2cWriteByte(low);
    toggleEnable(low);
}