#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>
#include <RotaryEncoder.h>
#include <MsTimer2.h>
#include <EEPROM.h>

#define SCREEN_ADDRESS 0x3C

#define INPUT_CONNECTED_PIN 12
#define INPUT_PIN 2
#define ENC_BTN_PIN 17
#define ENC_D1_PIN 4
#define ENC_D2_PIN 3
#define START_STOP_BTN_PIN 14

//Output pins are defined in the array below


//TODO :
//Add min and max values
//External clock
//Switch to another timer lib (FlexiTimer?)
//Switch to U8G2 for screen
//Save state to EEPROM when stopped

int outsPins[6] = {5, 6, 7, 8, 9, 10};
int outsValues[6] = {1, 2, 4, -4, 1, 1}; //positive - divide, negative - multiply, 0 - off
int outsPeriods[6];
int outsClocksCounts[6] = {0, 0, 0, 0, 0, 0};

bool clockMode;
bool clockModeOld;
int inputMode; //clock, reset, start/stop
int clockCount = 0;

int bpm = 120;
int bpmPeriod;
bool isPlaying = 0;

int displayTab = 0;
int displayTabOld;
bool needToChangeTab = 0;
bool buttonPushed = false;

bool changesSaved;

int encPositionOld = 0;

Adafruit_SSD1306 display(128, 64, &Wire, -1);
RotaryEncoder encoder(ENC_D1_PIN, ENC_D2_PIN, RotaryEncoder::LatchMode::TWO03);

void setup() {
  Serial.begin(9600);

  pinMode(INPUT_CONNECTED_PIN, INPUT_PULLUP);
  pinMode(ENC_BTN_PIN, INPUT_PULLUP);
  pinMode(START_STOP_BTN_PIN, INPUT_PULLUP);
  pinMode(INPUT_PIN, INPUT_PULLUP); //probably will need interrupt

  for (int i=0; i<6; i++) {
    pinMode(outsPins[i], OUTPUT);
  }

  display.begin(SSD1306_SWITCHCAPVCC, SCREEN_ADDRESS);

  updateScreen();
  updatePeriods();

  MsTimer2::set(1, internalClock); // 1ms period
  MsTimer2::start();
}

void loop() {
  checkInputs();
}

void internalClock() {
  if (isPlaying) {
    for (int i = 0; i<6; i++) {
      if (outsClocksCounts[i] >= outsPeriods[i]) {
        outsClocksCounts[i] = 0;
      }
      if (outsClocksCounts[i] == 0) {
        digitalWrite(outsPins[i], HIGH);
      }
      if (outsClocksCounts[i] == 15) {
        digitalWrite(outsPins[i], LOW);
      }
      outsClocksCounts[i]++;
    }
  }  
}

void updatePeriods() {
  bpmPeriod = 60000 / bpm;
  for (int i = 0; i<6; i++) {
    if (outsValues[i]>0) {
      outsPeriods[i] = bpmPeriod * outsValues[i];
    } else {
      outsPeriods[i] = bpmPeriod / outsValues[i] * - 1;      
    }
  }
}

void checkInputs() {
  clockMode = digitalRead(INPUT_CONNECTED_PIN);
  if (clockMode != clockModeOld) {
    updateScreen();
    clockModeOld = clockMode;
  }
  if (needToChangeTab == 0 && digitalRead(ENC_BTN_PIN) == 0) {
    needToChangeTab = 1;
  }

  if (needToChangeTab == 1 && digitalRead(ENC_BTN_PIN) == 1) {
    displayTabOld = displayTab;
    displayTab++;
    if (displayTab>6) {
      displayTab = 0;      
    }
    needToChangeTab = 0;
    updateScreen();
  }

  encoder.tick();
  int encPosition = encoder.getPosition();
  if (encPositionOld != encPosition) {
    int change = encPositionOld - encPosition;
    if (displayTab == 0) {
      bpm = bpm + change;
    } else {
      outsValues[displayTab-1] = outsValues[displayTab-1] + change;
    }
    updatePeriods();
    updateScreen();
    encPositionOld = encPosition;
  }

  if (!digitalRead(START_STOP_BTN_PIN) && !buttonPushed) {
    isPlaying = !isPlaying;
    buttonPushed = true;
  } else if (digitalRead(START_STOP_BTN_PIN) && buttonPushed) {
    buttonPushed = false;
  }
}

void updateScreen() {
  display.clearDisplay();

  //Tabs
  display.setCursor(0,0);
  display.setTextSize(1);
  if (displayTab == 0) {
    display.setTextColor(SSD1306_BLACK, SSD1306_WHITE);
    display.print(F(" "));
    display.setTextColor(SSD1306_WHITE);
    display.print(F(" bpm "));
  } else {
    display.setTextColor(SSD1306_BLACK, SSD1306_WHITE);
    display.print(F(" bpm"));
  }
  
  for (int i = 1; i <= 6; i++) {
    if (displayTab == i) {
      display.setTextColor(SSD1306_BLACK, SSD1306_WHITE);
      display.print(" ");
      display.setTextColor(SSD1306_WHITE);
      display.print(" ");
      display.print(i);
      display.print(" ");
    } else {
      display.setTextColor(SSD1306_BLACK, SSD1306_WHITE);
      display.print(" ");
      display.print(i);
    }
  }

  display.setTextColor(SSD1306_BLACK, SSD1306_WHITE);
  display.println(F("   "));

  display.println();
  
  //Content
  display.setTextSize(3);
  display.setTextColor(SSD1306_WHITE);

  if (displayTab == 0) {
    display.print(bpm);
    display.println(F("bpm")); 
  } else {
     if (outsValues[displayTab-1]>0) {
        display.print(F("/"));
      } else {
        display.print(F("x"));  
      }
      display.print(abs(outsValues[displayTab-1]));
  }

  display.display();
}