#include "U8glib.h"

U8GLIB_SSD1306_128X64 u8g(U8G_I2C_OPT_DEV_0 | U8G_I2C_OPT_NO_ACK | U8G_I2C_OPT_FAST);

int state = 0;
long timestamp_button_pressed;
unsigned long countdownStart;
int focus_time = 0;
int rest_time = 0;
int potentiometer_value_s = 0;
int potentiometer_value_r = 0;
int FocusMinute = 0;
int RestMinute = 0;
int RemainFocusTime = 0;
int RemainRestTime = 0;
int MidMinute = 0;
char buffer[20];
int string_width;
const int buzzerPin = 4;



//===============================================



void ButtonMode()
{
  if (millis() - timestamp_button_pressed > 200)
  {
    state = 1 - state; // Toggle between state 0 and state 1
    timestamp_button_pressed = millis();
  }
}



void ButtonStart()
{
  if (millis() - timestamp_button_pressed > 200)
  {
    if (state == 2)
    {
      state = 0;
      countdownStart = 0; // Reset the countdown start time(is it necessary? idk)
    }
    else
    {
      state = 2;
      countdownStart = millis();
    }
    timestamp_button_pressed = millis();
  }
}



void displayStateMessage() //Display current status
{
  switch (state)
  {
    case 0:
      string_width = u8g.getStrWidth("set FOCUS_TIME");
      u8g.drawStr(64-string_width/2, 60, "set FOCUS_TIME");
      break;
    case 1:
      string_width = u8g.getStrWidth("set REST_TIME");
      u8g.drawStr(64-string_width/2, 60, "set REST_TIME");
      break;
    case 2:
      if (0<=RemainFocusTime)
      {
        string_width = u8g.getStrWidth("REST_TIME");
        u8g.drawStr(64-string_width/2, 60, "REST_TIME");
      }
      else
      {
        string_width = u8g.getStrWidth("FOCUS_TIME"); //change this to switch blabla
        u8g.drawStr(64-string_width/2, 60, "FOCUS_TIME");
      break;
      }
  }
}



void displayMain() //Display time set and countdown
{
  switch(state)
  {
    case 0:
      u8g.firstPage();
        do
        {
          string_width = u8g.getStrWidth(buffer);
          sprintf(buffer, "%d:00", focus_time);
          u8g.drawStr(64 - string_width / 2, 10, buffer);
          displayStateMessage();
        }
        while (u8g.nextPage());
    
    potentiometer_value_s = map(analogRead(A0), 0, 1023, 5, 12);
    focus_time = 5 * potentiometer_value_s;
    break;

    case 1:
      u8g.firstPage();
        do
        {
          string_width = u8g.getStrWidth(buffer);
          sprintf(buffer, "%d:00", rest_time);
          u8g.drawStr(64 - string_width / 2, 10, buffer);
          displayStateMessage();
        }
        while (u8g.nextPage());

    potentiometer_value_r = map(analogRead(A0), 0, 1023, 1, potentiometer_value_s);
    rest_time = 5 * potentiometer_value_r;
    break;

    case 2:
      {
      FocusMinute=60000*focus_time, RemainFocusTime=countdownStart+FocusMinute-millis();
      RestMinute=60000*rest_time, RemainRestTime=countdownStart+FocusMinute+MidMinute+RestMinute-millis();
      MidMinute=5000; //Delay between Focus time and Rest time
      //countdownSession=FocusMinute+MidMinute+RestMinute; //One Session: Focus time + Delay + Rest time
      }
      if (0<=RemainFocusTime)
        {
          u8g.firstPage();
            do
              {
              string_width = u8g.getStrWidth(buffer);
              sprintf(buffer, "%02d:%02d", (int)(RemainFocusTime / 60000), (int)((RemainFocusTime % 60000) / 1000));
              u8g.drawStr(64 - string_width / 2, 10, buffer);
              }
            while (u8g.nextPage());
        }
      else if (0<=RemainFocusTime+MidMinute)
        {
          tone(buzzerPin, 1000);
          delay(5000);
          noTone(buzzerPin);
        }
      else if (0<=RemainRestTime)
        {
        u8g.firstPage();
          do
            {
            string_width = u8g.getStrWidth(buffer);
            sprintf(buffer, "%02d:%02d", (int)(RemainRestTime / 60000), (int)((RemainRestTime % 60000) / 1000));
            u8g.drawStr(64 - string_width / 2, 10, buffer);
            }
          while (u8g.nextPage());
        }
  }
}



//===============================================



void setup()
{
  u8g.setFont(u8g_font_8x13B);
  u8g.setColorIndex(1);

  pinMode(buzzerPin, OUTPUT);

  attachInterrupt(digitalPinToInterrupt(2), ButtonMode, RISING);
  attachInterrupt(digitalPinToInterrupt(3), ButtonStart, RISING);

  timestamp_button_pressed = millis();
}

void loop()
{
  displayMain();
}