#include <avr/interrupt.h>
#include <avr/io.h>
#include <stdbool.h>
#include <stdint.h>
#include <stdio.h>

#define F_CPU 16000000UL
#define DMX_CHANNELS 512

volatile uint8_t dmx_data[DMX_CHANNELS + 1]; // 1..512
volatile uint16_t dmx_index = 0;
volatile bool dmx_frame_ready = false;
volatile bool receiving = false;

extern void output_dmx_channels_1_24(void);

/* --- USART3 (DMX) init & ISR --- */
void uart3_init(void) {
  // uint16_t ubrr = (F_CPU / (16UL * 250000UL)) - 1; // 250000 baud
  // UBRR3H = (uint8_t)(ubrr >> 8);
  // UBRR3L = (uint8_t)ubrr;
  UBRR3L = 3;
  UCSR3B = (1 << RXEN3) | (1 << RXCIE3);
  UCSR3C = (1 << USBS3) | (1 << UCSZ31) | (1 << UCSZ30); // 8N2
}

ISR(USART3_RX_vect) {
  uint8_t status = UCSR3A;
  uint8_t data = UDR3;

  if (status & (1 << FE3)) {
    // Break detected: start new DMX packet
    receiving = true;
    dmx_index = 0;
    dmx_frame_ready = false;
    return;
  }

  if (!receiving)
    return;

  if (dmx_index == 0) {
    // start code (usually 0) - ignore/store as needed
    dmx_index++; // next byte will be channel 1
    return;
  }

  if (dmx_index <= DMX_CHANNELS) {
    dmx_data[dmx_index] = data;
    dmx_index++;
    if (dmx_index > DMX_CHANNELS) {
      dmx_frame_ready = true;
      receiving = false;
    }
  } else {
    dmx_frame_ready = true;
    receiving = false;
  }
}

/* --- USART0 (printf/debug) init & putchar --- */
void uart0_init(uint32_t baud) {
  // uint16_t ubrr = (uint16_t)((F_CPU / (16UL * baud)) - 1UL);
  // UBRR0H = (uint8_t)(ubrr >> 8);
  // UBRR0L = (uint8_t)ubrr;
  UBRR0L = 8;
  UCSR0B = (1 << TXEN0);                  // enable transmitter
  UCSR0C = (1 << UCSZ01) | (1 << UCSZ00); // 8 data, 1 stop, no parity
}

int uart0_putchar(char c, FILE *stream) {
  if (c == '\n')
    uart0_putchar('\r', stream); // CRLF
  while (!(UCSR0A & (1 << UDRE0)))
    ; // wait until buffer empty
  UDR0 = (uint8_t)c;
  return 0;
}

/* Create a FILE stream for stdout */
static FILE uart0_stdout =
    FDEV_SETUP_STREAM(uart0_putchar, NULL, _FDEV_SETUP_WRITE);

int main(void) {
  cli();

  DDRJ |= 1 << 5; // enable rs485 receiver

  uart3_init();
  uart0_init(115200); // debug baud

  // Hook stdout to UART0
  stdout = &uart0_stdout;

  // init DMX buffer
  for (uint16_t i = 1; i <= DMX_CHANNELS; ++i)
    dmx_data[i] = 0;

  sei();

  // Example usage
  printf("DMX receiver started\r\n");

  while (1) {
    if (dmx_frame_ready) {
      // Example debug: print first 8 channels
      printf("DMX frame received. Ch1..8: ");
      for (uint8_t i = 1; i <= 8; ++i) {
        printf("%u ", dmx_data[i]);
      }
      printf("\r\n");

      dmx_frame_ready = false;
    }

    output_dmx_channels_1_24();

    // other app code...
  }

  return 0;
}