// Intended for an ATTiny 1614
// Fab Academy 2022
// Jonathan Blok <guanothan@gmail.com>

// Pin configuration
const int bd_speaker = PIN_PA5;
const int sd_speaker = PIN_PA6;
const int hh_speaker = PIN_PA7;

const int bd_st0_conf_pin = PIN_PA3;
const int bd_st1_conf_pin = PIN_PB2;
const int sd_st0_conf_pin = PIN_PA2;
const int sd_st1_conf_pin = PIN_PB1;
const int hh_st0_conf_pin = PIN_PA1;
const int hh_st1_conf_pin = PIN_PA4;

// Instrument configuration
const int bd_hz = 200;
const int bd_length = 10;
const int sd_hz = 300;
const int sd_length = 50;
const int hh_hz = 420;
const int hh_length = 25;

// Configuration matrix
int seq_conf[3][2] = {{0,0},{0,0},{0,0}};

const int bpm = 150;
bool step;
int bpm_in_ms;


void setup() {
   Serial.begin(9600);
   step = false;    // start at step 0
   pinMode(bd_st0_conf_pin, INPUT_PULLUP);
   pinMode(bd_st1_conf_pin, INPUT_PULLUP);
   pinMode(sd_st0_conf_pin, INPUT_PULLUP);
   pinMode(sd_st1_conf_pin, INPUT_PULLUP);
   pinMode(hh_st0_conf_pin, INPUT_PULLUP);
   pinMode(hh_st1_conf_pin, INPUT_PULLUP);

   pinMode(bd_speaker, OUTPUT);
   pinMode(sd_speaker, OUTPUT);
   pinMode(hh_speaker, OUTPUT);
   bpm_in_ms = (int) (60.0 / (double) bpm * 1000.0);
}

void loop() {
  doStep(step);
  step = !step;     // switch the step
  delay(bpm_in_ms); // bpm to ms
  checkSequencerConfiguration();
}

void doStep(int step){
  int sum_hz = 0;
  int sum_length = 0;
  int inst_counter = 0;
  if(seq_conf[0][step] == 1) {
    sum_hz += bd_hz;
    sum_length += bd_length;
    inst_counter++;
  }
  if(seq_conf[1][step] == 1) {
    sum_hz += sd_hz;
    sum_length += sd_length;
    inst_counter++;
  }
  if(seq_conf[2][step] == 1) {
    sum_hz += hh_hz;
    sum_length += hh_length;
    inst_counter++;
  }
  if(inst_counter != 0 ){
    play_instrument(sum_hz/inst_counter, sum_length/inst_counter, hh_speaker);
  }
}

void checkSequencerConfiguration() {
  // Update sequencer configuration from buttons
  // Inverted due to pullup/pulldown
  seq_conf[0][0] = 1 - digitalRead(bd_st0_conf_pin);
  seq_conf[0][1] = 1 - digitalRead(bd_st1_conf_pin);
  seq_conf[1][0] = 1 - digitalRead(sd_st0_conf_pin);
  seq_conf[1][1] = 1 - digitalRead(sd_st1_conf_pin);
  seq_conf[2][0] = 1 - digitalRead(hh_st0_conf_pin);
  seq_conf[2][1] = 1 - digitalRead(hh_st1_conf_pin);
}

void play_instrument(int in_hz, int in_length, int speaker_pin) {
  tone(speaker_pin, in_hz, in_length);              // minimally 31hz
}