#include <avr/io.h>
#include <util/delay.h>
#include <stdio.h>

// Definovanie LCD pinov
#define RS PD2
#define RW PD3
#define E  PD4
#define D4 PD5
#define D5 PD6
#define D6 PD7
#define D7 PB0

// Definovanie klávesnicových pinov
#define ROWS 4
#define COLS 4
char keys[ROWS][COLS] = {
  {'1', '2', '3', 'A'},
  {'4', '5', '6', 'B'},
  {'7', '8', '9', 'C'},
  {'*', '0', '#', 'D'}
};
uint8_t rowPins[ROWS] = {7, 6, 14, 15};
uint8_t colPins[COLS] = {16, 17, 19, 18};

// Function prototypes
void lcd_init(void);
void lcd_command(uint8_t cmd);
void lcd_data(uint8_t data);
void lcd_print(const char *str);
char klavesa(void);

void lcd_init(void) {
  // Set LCD pins as output
  DDRD |= (1 << RS) | (1 << RW) | (1 << E) | (1 << D4) | (1 << D5) | (1 << D6);
  DDRB |= (1 << D7);
  _delay_ms(20);
  lcd_command(0x02); // Inicializácia LCD displaya do 4-bitového režimu
  lcd_command(0x28); 
  lcd_command(0x0C); 
  lcd_command(0x06); 
  lcd_command(0x01); // vyčistenie displaya
  _delay_ms(2);
}

void lcd_command(uint8_t cmd) {
  PORTD = (cmd & 0xF0) | (1 << E);
  _delay_us(1);
  PORTD &= ~(1 << E);
  _delay_us(200);
  PORTD = ((cmd << 4) & 0xF0) | (1 << E);
  _delay_us(1);
  PORTD &= ~(1 << E);
  _delay_ms(2);
}

void lcd_data(uint8_t data) {
  PORTD = (data & 0xF0) | (1 << RS) | (1 << E);
  _delay_us(1);
  PORTD &= ~(1 << E);
  _delay_us(200);
  PORTD = ((data << 4) & 0xF0) | (1 << RS) | (1 << E);
  _delay_us(1);
  PORTD &= ~(1 << E);
  _delay_ms(2);
}

void lcd_print(const char *str) {
  while (*str) {
    lcd_data(*str++);
  }
}

char klavesa(void) {
  for (uint8_t i = 0; i < COLS; i++) {
    DDRB = (1 << colPins[i]);
    PORTB = ~(1 << colPins[i]);
    _delay_us(5);
    for (uint8_t j = 0; j < ROWS; j++) {
      if (!(PINB & (1 << rowPins[j]))) {
        return keys[j][i];
      }
    }
  }
  return 0;
}

int main(void) {
  lcd_init();
  lcd_print("Press 1: Key");
  lcd_command(0xC0); // Nastavenie kurzora do 2 riadku
  lcd_print("Press 2: Write");

  while (1) {
    char key = klavesa();
    if (key == '1') {
      lcd_command(0x01); // vyčistenie displaya
      lcd_print("Key pressed: ");
      while (1) {
        key = klavesa();
        if (key) {
          lcd_command(0x8D); // Nastavenie kurzora na 13 pozíciu, čiže prvú v druhom riadku
          lcd_data(key);
        }
      }
    } else if (key == '2') {
      lcd_command(0x01); // vyčistenie displaya
      uint8_t cursorPosition = 0;
      while (1) {
        key = klavesa();
        if (key) {
          if (cursorPosition == 32) {
            lcd_command(0x01); // vyčistenie displaya
            cursorPosition = 0;
          }
          lcd_command(0x80 + cursorPosition); // Reset kurzora na pôvodnú pozíciu
          lcd_data(key);
          cursorPosition++;
        }
      }
    }
  }
  return 0;
}