#include <stdio.h>
#include <avr/pgmspace.h>
#include <avr/io.h>
#include <avr/interrupt.h>

#include "delay.h"
#include "morse.h"

/* Definitions for pins */
#define PORTB_PTT (1 << 0)
#define PORTB_SYNCn (1 << 2)
#define PORTB_LED (1 << 4)

/* Specify ID here */
static const uint8_t renard_id = 0;

static const uint8_t num_renards_cycle = 4;
// colon (:) represents ERROR
static const char letters[] = "eish:";
static const char unique_letter = letters[renard_id];

volatile uint8_t reset_time;
volatile uint8_t systick;        /* Timer (100Hz increment) */
volatile uint8_t seconds;
volatile uint16_t minutes;

/*---------------------------------------------------------*/
/* 100Hz timer interrupt generated by OC2                  */
/*---------------------------------------------------------*/
ISR(TIMER1_COMPA_vect)
{
    systick++;
    if (systick == 10) {
        systick = 0;
        seconds += 1;
    }

    if (seconds == 60) {
        seconds = 0;
        minutes++;
    }

    if (reset_time) {
        reset_time = 0;
        seconds = 0;
        minutes = 0;
    }
}

static int inittimer(void)
{
    /* Start 100Hz system timer (TC2.OC) */
    TCCR0B |= (1 << WGM02); // Configure timer for CTC mode
    TIMSK  |= (1 << OCIE1A); // enable overflow interrupt
    OCR1A = (uint8_t)(F_CPU / 64 / 1000 / 100 - 1); // Set CTC compare value to 10ms
    TCCR0B |= ((1 << CS10) | (1 << CS11)); // Start timer at Fcpu/64

    // Enable interrupts
    sei();

    return 0;
}

#define PTT_LOGIC_LOW 0

#if PTT_LOGIC_LOW
void dah(void)
{
    PORTB = PORTB_LED; // LED is non-inverted logic
    delay_ms(3*DIT_DURATION);

    PORTB = PORTB_PTT; // PTT is inverted logic
    delay_ms(DIT_DURATION);
}

void dit(void)
{
    PORTB = PORTB_LED; // LED is non-inverted logic
    delay_ms(DIT_DURATION);

    PORTB = PORTB_PTT; // PTT is inverted logic
    delay_ms(DIT_DURATION);
}
#else
void dah(void)
{
    PORTB = PORTB_PTT | PORTB_LED;
    delay_ms(3*DIT_DURATION);

    PORTB = 0;
    delay_ms(DIT_DURATION);
}

void dit(void)
{
    PORTB = PORTB_PTT | PORTB_LED;
    delay_ms(DIT_DURATION);

    PORTB = 0;
    delay_ms(DIT_DURATION);
}
#endif

int main(void)
{
    systick = 0;
    seconds = 0;
    minutes = 0;
    reset_time = 0;

    /* Enable PTT output on PB0 */
#if PTT_LOGIC_LOW
    PORTB = PORTB_PTT;
#endif
    /* LED is never inverted */
    DDRB  = PORTB_PTT | PORTB_LED;

    /* initialise timer interrupt */
    inittimer();

    static char *morse_string = "MO ";
    morse_string[2] = unique_letter;

    const int permanent = (unique_letter == ':');

    // In order to have all foxes transmitting all the time
    // before sync
    int sync_pending = 1;

    delay_ms(12*DIT_DURATION);
    morse("HB9HI");
    delay_ms(12*DIT_DURATION);

    while (1) {
        if ((PINB & PORTB_SYNCn) == 0) {
            reset_time = 1;
            sync_pending = 0;
        }

        if (permanent || sync_pending) {
            morse(morse_string);
            delay_ms(6*DIT_DURATION);
        }
        else if (minutes >= 10) { // see README.md
            /* renard id 0: start at (k * num_renards_cycle) * 60, end at (k * num_renards_cycle) * 60 + 55 */
            const int in_timeslot = (minutes % num_renards_cycle) == renard_id;

            if (in_timeslot && seconds < 55) {
                morse(morse_string);
                delay_ms(6*DIT_DURATION);
            }
            else {
                delay_ms(DIT_DURATION);
            }
        }
        else {
            /* renard id 0: start every 30s, with an additional 2s offset depending on renard_id */
            const uint32_t second_offset = seconds % 30;

            if (second_offset == 2 * renard_id) {
                morse_char(unique_letter);
                delay_ms(1000); // avoid retrigger in same second
            }
        }
    }

    return 0;
}