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

#define DHT_PIN_MASK (1 << PB0)
#define BUTTON_RED_MASK (1 << PD7)
#define BUTTON_YEL_MASK (1 << PD6)
#define BUTTON_BLK_MASK (1 << PB7)

#define LCD_RS_MASK (1 << PB4)
#define LCD_EN_MASK (1 << PB5)
#define LCD_D4_MASK (1 << PD5)
#define LCD_D5_MASK (1 << PD4)
#define LCD_D6_MASK (1 << PD3)
#define LCD_D7_MASK (1 << PD2)

#define LCD_DATA_PORT PORTD
#define LCD_CTRL_PORT PORTB
#define LCD_DATA_DDR DDRD
#define LCD_CTRL_DDR DDRB

#define BUTTON_PORT PORTD
#define BUTTON_PIN PIND
#define BUTTON_DDR DDRD

#define BUTTON_RED 0
#define BUTTON_YEL 1

#define TEMPERATURE_C 0
#define TEMPERATURE_F 1
#define TEMPERATURE_K 2

volatile unsigned char escala = TEMPERATURE_C;
volatile unsigned char tela = 0;

void LCD_pulse_enable(void) {
    LCD_CTRL_PORT |= LCD_EN_MASK;
    _delay_us(1);
    LCD_CTRL_PORT &= ~LCD_EN_MASK;
    _delay_us(100);
}

void LCD_send_command(unsigned char command) {
    LCD_CTRL_PORT &= ~LCD_RS_MASK; // Set RS to command mode
    LCD_DATA_PORT = command & 0xF0; // Send upper nibble
    LCD_pulse_enable();
    LCD_DATA_PORT = (command << 4) & 0xF0; // Send lower nibble
    LCD_pulse_enable();
}

void LCD_send_data(unsigned char data) {
    LCD_CTRL_PORT |= LCD_RS_MASK; // Set RS to data mode
    LCD_DATA_PORT = data & 0xF0; // Send upper nibble
    LCD_pulse_enable();
    LCD_DATA_PORT = (data << 4) & 0xF0; // Send lower nibble
    LCD_pulse_enable();
}

void LCD_init(void) {
    _delay_ms(100); // Wait for LCD to power up
    LCD_DATA_DDR |= 0xF0;
    LCD_CTRL_DDR |= LCD_RS_MASK | LCD_EN_MASK;
    LCD_send_command(0x33);
    _delay_ms(5);
    LCD_send_command(0x32);
    _delay_ms(5);
    LCD_send_command(0x28); // 4-bit mode, 2 lines, 5x7 font
    _delay_ms(5);
    LCD_send_command(0x0C); // Display on, cursor off, blink off
    _delay_ms(5);
    LCD_send_command(0x01); // Clear display
    _delay_ms(5);
    LCD_send_command(0x06); // Set entry mode (increment cursor, no display shift)
    _delay_ms(5);
}

void show_hello_message(void) {
    LCD_send_command(0x01); // Clear display
    _delay_ms(5);
    LCD_send_data('O');
    LCD_send_data('l');
    LCD_send_data('a');
    LCD_send_data(',');
    LCD_send_data(' ');
    LCD_send_data('P');
    LCD_send_data('&');
    LCD_send_data('R');
    LCD_send_data(' ');
    LCD_send_data('t');
    LCD_send_data('e');
    LCD_send_data('c');
    LCD_send_data('h');
    LCD_send_data('\'');
    LCD_send_data('s');
    _delay_ms(2000);
    tela++;
    configuracao();
}

void configuracao(void) {
    LCD_send_command(0x01); // Clear display
    _delay_ms(5);
    LCD_send_data('E');
    LCD_send_data('s');
    LCD_send_data('c');
    LCD_send_data('o');
    LCD_send_data('l');
    LCD_send_data('h');
    LCD_send_data('a');
    LCD_send_data(' ');
    LCD_send_data('o');
    LCD_send_data(' ');
    LCD_send_data('m');
    LCD_send_data('o');
    LCD_send_data('d');
    LCD_send_data('o');
    LCD_send_data(':');
    LCD_send_data(' ');
    LCD_send_data('1');
    LCD_send_data('(');
    LCD_send_data('C');
    LCD_send_data(')');
    LCD_send_data(' ');
    LCD_send_data('2');
    LCD_send_data('(');
    LCD_send_data('K');
    LCD_send_data(')');
    LCD_send_data(' ');
    LCD_send_data('3');
    LCD_send_data('(');
    LCD_send_data('F');
    LCD_send_data(')');
    while (1) {
        if (!(BUTTON_PIN & BUTTON_RED_MASK)) {
            escala = TEMPERATURE_C;
            tela++;
            show_temperature(escala);
            break;
        } else if (!(BUTTON_PIN & BUTTON_YEL_MASK)) {
            escala = TEMPERATURE_F;
            tela++;
            show_temperature(escala);
            break;
        } else if (!(BUTTON_PIN & BUTTON_BLK_MASK)) {
            escala = TEMPERATURE_K;
            tela++;
            show_temperature(escala);
            break;
        }
    }
}

void show_temperature(unsigned char escala) {
  float temperatura = 25.0; // DHT_readTemperature(); Simulação de leitura de temperatura
  char buffer[16];

  LCD_send_command(0x01); // Clear display
  _delay_ms(5);
  LCD_send_data(' ');
  LCD_send_data('T');
  LCD_send_data('e');
  LCD_send_data('m');
  LCD_send_data('p');
  LCD_send_data(':');
  LCD_send_data(' ');

  switch (escala) {
    case TEMPERATURE_C:
      sprintf(buffer, "%.2fC", temperatura);
      break;
    case TEMPERATURE_F:
      sprintf(buffer, "%.2fF", (temperatura * 9.0 / 5.0) + 32.0);
      break;
    case TEMPERATURE_K:
      sprintf(buffer, "%.2fK", temperatura + 273.15);
      break;
  }

  for (int i = 0; buffer[i] != '\0'; i++) {
    LCD_send_data(buffer[i]);
  }
}

void setup() {
  BUTTON_DDR &= ~(BUTTON_RED_MASK | BUTTON_YEL_MASK | BUTTON_BLK_MASK);
  BUTTON_PORT |= BUTTON_RED_MASK | BUTTON_YEL_MASK | BUTTON_BLK_MASK;

  LCD_init();

  // Configura a interrupção externa INT0 (PD2)
  EICRA |= (1 << ISC01) | (1 << ISC00); // Rising edge
  EIMSK |= (1 << INT0); // Habilita a interrupção INT0

  sei(); // Habilita as interrupções globais
  show_hello_message();
}

ISR(INT0_vect) {
  tela = 0;
  show_hello_message();
}

void loop() {
  // Nada a ser feito no loop principal, tudo é tratado por interrupções
}