#include <avr/interrupt.h>
#include <avr/pgmspace.h>
#include "audio.h"

struct fadeLED {
  int pin;
  int brit;
  int fade;
};

const int ledCount = 4;
const int ledHigh = 200;
const int fadeStep = 10;

fadeLED leds[ledCount];

unsigned long pMilis = 0;
long interval = 20;

int i;

int curLed = 0;

volatile uint16_t pos;


void start_timer(){
    TCCR0A = (1 << WGM01);
    OCR0A = ((F_CPU / 8 / SAMPLE_RATE)-1);
    TIMSK0 |= (1 << OCIE0A);
    TCCR0B = (1 << CS01);
}

void stop_timer(){
    cli();
    TIMSK0 &=~ (1 << OCIE0A);
    TCNT0 = 0;
}

void start_pwm(){
    TCCR1A = (1 << COM1A1) | (1 << WGM10);
    TCCR1B = (1 << WGM12) | (1 << CS10);
    OCR1A = 128;
}

void setup() {
  fadeLED tled = {3, 0, 5};
  leds[0] = tled;
  tled = {5, ledHigh, fadeStep};
  leds[1] = tled;
  tled = {6, ledHigh, fadeStep};
  leds[2] = tled;
  tled = {10, ledHigh, fadeStep};
  leds[3] = tled;

  for(i=0; i < ledCount; i++) {
    pinMode(leds[i].pin, OUTPUT);
    analogWrite(leds[i].pin, leds[i].brit);
  }

  DDRB = (1 << PB1);
  DDRB |= (1 << PB5);

  start_pwm();
  delay(500);
  pos = (START_POS + 0);
  sei();
  start_timer();
}

void loop() {
  if (pos == AUDIO_SIZE) {
      stop_timer();
      pos = (START_POS + 0);
      PORTB |= (1 << PB5);
  }
  interval = round(analogRead(0)/10);
  unsigned long curMilis = millis();
  if(curMilis - pMilis >= interval) {
    pMilis = curMilis;
    int nextLed = curLed + 1;
    if(nextLed >= ledCount) {
      nextLed = 0;
    }
    bool shift = false;
    bool setNext = false;
    leds[curLed].brit += leds[curLed].fade;
    if(leds[curLed].brit <= 0 || leds[curLed].brit >= ledHigh) {
      if(leds[curLed].brit > ledHigh) leds[curLed].brit = ledHigh;
      if(leds[curLed].brit < 0) leds[curLed].brit = 0;
      if(leds[curLed].brit >= ledHigh) {
        shift = true;
      }
      leds[curLed].fade = -leds[curLed].fade;
      if(leds[curLed].fade > 0) {
        leds[nextLed].fade = -fadeStep;
        setNext = true;
      }
    }
    if(setNext) {
      leds[nextLed].brit += leds[nextLed].fade;
      if(leds[nextLed].brit > ledHigh) {
        leds[nextLed].brit = ledHigh;
      }
      if(leds[nextLed].brit < 0) {
        leds[nextLed].brit = 0;
      }
    }
    for(i=0; i < ledCount; i++) {
      if(i == curLed || i == nextLed) {
        analogWrite(leds[i].pin, leds[i].brit);
      }
    }
    if(shift) {
      curLed++;
      if(curLed >= ledCount) {
        curLed = 0;
      }
    }
  }
}

ISR(TIMER0_COMPA_vect)
{
    OCR1A = pgm_read_byte(&AUDIO_DATA[pos]);
    if (pos < AUDIO_SIZE) {
      pos++;
    }
}