// Better sequencer which uses interrupts

#include <Adafruit_MCP4728.h>
#include <Wire.h>

Adafruit_MCP4728 mcp;


float tuning[37];
float voltrange = 4.85;  // measured this, probably not accurate
float octave = 4096.0 / voltrange; // number of DAC steps in an octave


// melody

// int pitch[] = { 4, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
// -1, -1, -1, -1, -1, -1, -1, -1,-1, -1, -1, -1,2, -1, -1, -1, };
// int dur[] = { 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
//             0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0,  };

// hi hat

int pitch[] = { 1, -1, 3, -1, 4, -1, 5, -1, };


int note = 0;
int phrase = 8;
int grains_n = 12;
int grainc = 0;
int grainsize = 20;

int s;
int bpm = 9000;
float beat_s = 60.0 / (float)bpm;
float note_s = beat_s * grains_n;
float beat_m = 1000.0 * beat_s; 
bool noteon = false;
int beat = false;
long notestart, notedur, barstart;
int target, slew;
float decay = 0.1;


void setup() {
  Serial.begin(115200);

  float freq = (float)bpm / 60.0;

  int ocr = round(16000000.0 / (1024.0 * freq )) - 1;
  Serial.println(ocr);
  if( ocr < 65536 ) {

    cli();

    TCCR1A = 0;// set entire TCCR1A register to 0
    TCCR1B = 0;// same for TCCR1B
    TCNT1  = 0;//initialize counter value to 0
    OCR1A = ocr; //ocr; 
    // turn on CTC mode
    TCCR1B |= (1 << WGM12);
    // Set CS10 and CS12 bits for 1024 escaler
    TCCR1B |= (1 << CS12) | (1 << CS10);  
    // enable timer compare interrupt
    TIMSK1 |= (1 << OCIE1A);

    sei();

  } else {
    Serial.println("BPM out of range");
  }

  if (!mcp.begin(0x64)) {
    while (1) {
      delay(100);
    }
  }

  // randomSeed(analogRead(A0));
  mcp.setSpeed(800000L);
  make_tuning(12);
  note=0;
  notestart=millis();
}

void make_tuning(int edo) {
  float n0 = 0;
  float edof = (float)edo;
  for( int i = 0; i < 37; i++ ) {
      tuning[i] = round(n0 + octave * (float)i / edof);
  }

}


ISR(TIMER1_COMPA_vect){ // called once every beat
  beat = true;
}


bool play_grain(int dur) {
  return true;
//  return random(0, 1000) > (float)dur * decay;
}


void loop() {
  int now = millis();
  if( beat ) {
    beat = false;
    noteOn(pitch[s], now - notestart);
    grainc++;
    if( grainc > grains_n ) {
      grainc = 0;
      s += 1;
      if( s == phrase ) {
        s = 0;
        notestart = now;
      }
      grainc = 0;
      Serial.println(s);
    }
  } else {
    if( noteon && now - notestart > grainsize ) {
      noteOff();
    }
  } 
}


void noteOn(int note, int dur) {
  Serial.println("noteOn");
  if( note > -1 && play_grain(dur) ) {
    mcp.setChannelValue(MCP4728_CHANNEL_A, tuning[note]);
    mcp.setChannelValue(MCP4728_CHANNEL_B, 4095);
    noteon = true;
  }
}

void noteOff() {
    mcp.setChannelValue(MCP4728_CHANNEL_B, 0);
    noteon = false;
    Serial.println("noteOff");
}