/*
Blink

Turns an LED on for one second, then off for one second, repeatedly.

Most Arduinos have an on-board LED you can control. On the UNO, MEGA and ZERO
it is attached to digital pin 13, on MKR1000 on pin 6. LED_BUILTIN is set to
the correct LED pin independent of which board is used.
If you want to know what pin the on-board LED is connected to on your Arduino
model, check the Technical Specs of your board at:
https://www.arduino.cc/en/Main/Products

modified 8 May 2014
by Scott Fitzgerald
modified 2 Sep 2016
by Arturo Guadalupi
modified 8 Sep 2016
by Colby Newman

This example code is in the public domain.

https://www.arduino.cc/en/Tutorial/BuiltInExamples/Blink
*/
#include <Arduino.h>
#include <SoftwareSerial.h>
#include <avr/interrupt.h>
#include <avr/io.h>

SoftwareSerial midi_uart(10, 11); // RX, TX

const double bpm = 140.0;
const int led1_pin = 7;
const int led2_pin = 9;
const int ext_clock_pin = 5;
unsigned int reload = 0xF424;
volatile unsigned long count = 0;
volatile int state = HIGH;
int md_notes[16] = {36, 38, 40, 41, 43, 45, 47, 48,
                    50, 52, 53, 55, 57, 59, 60, 62};
volatile unsigned long count_last[8] = {0, 0, 0, 0, 0, 0, 0, 0};

void flash1() {
  static boolean output = HIGH;
  digitalWrite(led1_pin, output);
  output = !output;
}

void flash2() {
  static boolean output = HIGH;
  digitalWrite(led1_pin, output);
  output = !output;
}

void ext_clock_pulse() { flash2(); }

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

  // LED
  pinMode(led1_pin, OUTPUT);
  digitalWrite(led1_pin, LOW);
  pinMode(led2_pin, OUTPUT);
  digitalWrite(led2_pin, LOW);

  // BUT
  pinMode(ext_clock_pin, INPUT_PULLUP);
  attachInterrupt(digitalPinToInterrupt(ext_clock_pin), ext_clock_pulse,
                  CHANGE);

  midi_uart.begin(31250);
  cli();
  TCCR1A = 0;
  TCCR1B = 0;
  OCR1A = reload;
  //  TCCR1B = (1 << WGM12) | (1 << CS11); // SLOW
  TCCR1B = (1 << WGM12) | (1 << CS10); // FAST
  TIMSK1 = (1 << OCIE1A);
  sei();
  //  Serial.println("TIMER1 Setup Finished.");
}

int div_to_clk(float div) {
  double clk_pulse_per_second = 40.;
  double beat_per_bar = 4.;
  double bar_ns = 60. / bpm * beat_per_bar * clk_pulse_per_second;
  double d_c = bar_ns / div;
  return d_c;
}

void noteOn(int cmd, int pitch, int velocity) {
  midi_uart.write(cmd);
  midi_uart.write(pitch);
  midi_uart.write(velocity);
}

// void subdiv(unsigned int count, unsigned int div, unsigned int md_note_nr) {
//   if (count % div == 0) {
//     noteOn(0x90, md_notes[md_note_nr], 0x64);
//   }
// }
void subdiv(unsigned int count, unsigned int div, unsigned int md_note_nr) {
  if (count >= count_last[div] + div_to_clk(div)) {
    count_last[div] = count;
    noteOn(0x90, md_notes[md_note_nr], 0x64);
  }
}

ISR(TIMER1_COMPA_vect) {
  count++;
  //  flash1();

  for (int i = 0; i < 8; i++) {
    subdiv(count, i + 1, i);
  }
}

void loop() {
  Serial.println(count); // do anything
  delay(200);
  //  digitalWrite(LED_pin, state);
  //  // play notes from F#-0 (0x1E) to F#-5 (0x5A):
  //  for (int note = 0x1E; note < 0x5A; note++) {
  //    // Note on channel 1 (0x90), some note value (note), middle velocity
  //    (0x45): noteOn(0x90, note, 0x45); delay(1000);
  //    // Note on channel 1 (0x90), some note value (note), silent velocity
  //    (0x00): noteOn(0x90, note, 0x00); delay(100);
  //  }
}