#include <RTClib.h>
#include<ezButton.h>
#include <LiquidCrystal_I2C.h>

//  lcd object : setting register address 0x27
LiquidCrystal_I2C lcd(0x27, 20, 4);

// Create an object to work with the RTC module
RTC_DS1307 rtc;

//  clock variables
int year = 0;
int month = 0;
int day = 0;
int hour = 0;
int minute = 0;
int second = 0;

//  alarm variables
int alarm_hours = 0;
int alarm_minutes = 0;

//  encoder variables
byte clk = 2;
byte dt = 3;
byte sw = 4;

int counter = 0;

int flag = 1,prev_counter=-1; //values changed to 1 and -1 
//(the 1st option should also be display automatically) 

ezButton button(sw);

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

  lcd.init();  //  initialize the lcd.
  lcd.clear();  //  clears screen & moves cursor to  top left corner.
  lcd.backlight();  //  turn on the backlight.

  //  initial messages
  lcd.clear();
  if (!rtc.begin()) {
    lcd.clear();
    // lcd_print(0,0,"RTC not initialised");
    while (true);
  }
  lcd_print(0, 0, "RTC found");
  delay(1000);
  lcd.clear();
  lcd_print(0, 0, "Welcome!");
  delay(2000);

  // Specifies a function to call when an external interrupt occurs.
  // when CLK pin goes LOW, the  encoder() is called
  attachInterrupt(digitalPinToInterrupt(clk), encoder, FALLING);
  //   attachInterrupt(interrupt, function, mode)

  // interrupt: the number of the interrupt (int)

  // function: the function to call when the interrupt occurs; 
  // this function must take no parameters and return nothing. 
  // This function is sometimes referred
  // to as an interrupt service routine.

  // mode defines when the interrupt should be triggered. 
  //Four constants are predefined 
  // a. LOW to trigger the interrupt whenever the pin is low,
  // b. CHANGE to trigger the interrupt whenever the pin changes value
  // c. RISING to trigger when the pin goes from low to high,
  // d. FALLING for when the pin goes from high to low

  // digitalPinToInterrupt(pin)
  // Pin number of the interrupt, tells the microprocessor which pins
  // to monitor. The pin depends on the microcontroller being used.

  button.setDebounceTime(25);

}

void loop()
{
  button.loop();
  if (button.isPressed())
  {
        select_mode();
  }
  mode_selector();

  //  for better working of simulator
  delay(10);
}

void encoder() 
{
  prev_counter = counter;
  // if rotated clockwise increase 'counter' else decrease 'counter'
  if (digitalRead(dt)  ==  HIGH)
      counter++;
  else
      counter--;

  /*Delete from her and pu in mode_selector()
  // restricts counters min value to go below 0 and max value to go above 3 
  counter = constrain(counter, 0, 3);*/
  flag = 1;  
}


void mode_selector() 
{
    // restricts counters min value to go below 0 and max value to go above 3 
    //shifted here so its applicable only to this function
    counter = constrain(counter, 0, 3);
    if ((flag == 1) && (prev_counter != counter))
    {
      if (counter  ==  0) 
      {
        lcd.clear();
        lcd_print(0,0,"Date and Time");
      }
      else if (counter  ==  1) 
      {
        lcd.clear();
        lcd_print(0,0,"Set Alarm");
      }
      else if (counter  ==  2) 
      {
        lcd.clear();
        lcd_print(0,0,"Stopwatch");
      }
      else if (counter  ==  3) 
      {
        lcd.clear();
        lcd_print(0,0,"Countdown Timer");
      }
      flag = 0;
    }
}

void select_mode() 
{
  if (counter  ==  0)
      get_time();
  if (counter  ==  1)
      set_alarm();
  if (counter  ==  2)
      start_stopwatch();
  if (counter  ==  3)
      countdown();
}


void current_time() 
{
  //  getting current date and time
  DateTime current = rtc.now();
  year = current.year();
  month = current.month();
  day = current.day();
  hour = current.hour();
  minute = current.minute();
  second = current.second();
}
// udf function to print message on lcd
void lcd_print(int x, int y, String message) 
{
  lcd.setCursor(x, y);
  lcd.print(message);
}

void get_time() 
{
    // while loop used so that the digital clock animation can be seen
    // while doing this animayion under date time, when a button 
    // click is encountered, exit the current (DateTime) mode
    while (true) 
    {
      //  looping button
      button.loop();
      if (button.isPressed()) 
      {
        lcd.clear();

        //  let's run the mode_selector
        prev_counter = -1;
        flag = 1;

        //  break the loop
        break;
      }

      //  getting current time
      current_time();
      String current_date = "Date : " + String(day) + "/" + String(month) +
                            "/" + String(year);
      lcd_print(0, 0, "Date and Time");
      lcd_print(0, 1, current_date);
    
      String hr="",minu="",sec="";
      if (hour <10)
        hr="0"+String(hour);
      else 
        hr=String(hour);

      if (minute <10)
        minu="0"+String(minute);
      else 
        minu=String(minute);

      if (second <10)
        sec="0"+String(second);
      else 
        sec=String(second);

      String current_time = "Time : " + hr + ":" + minu + ":" + sec ;
      lcd_print(0, 2, current_time);

    }
}



void set_alarm()
{
  lcd_print(0, 0, "Enter hours : ");
  alarm_hours = set_value(0, 23);
  Serial.print(alarm_hours);
  lcd_print(0, 0, "Enter Minutes : ");
  alarm_minutes = set_value(0, 59);
  //  printing data
  lcd.clear();
  lcd_print(0, 0, "Alarm is set for ");
  lcd_print(0, 1, String(alarm_hours));
  lcd_print(3, 1, " Hours and ");
  lcd_print(0, 2, String(alarm_minutes));
  lcd_print(3, 2, " Minutes");
  delay(5000);
}

void start_stopwatch()
{
  int stopwatch_hour, stopwatch_minute, stopwatch_second = 0,last_second;

  while (true) 
  {
      button.loop();
      if (button.isPressed()) 
      {
        prev_counter = -1;
        flag = 1;

        //Giving a delay of 5 Secs,to give a feel that we 
        //have stopped the watch and then, back to selector mode
        delay(5000);
        lcd.clear();
        break;
      }

      //this method is important when compared to the previousdelay menthod,
      // bcz while being on delay the button pressed of encoder is not detected, 
      // when contineous checking is done, there is no loop hole for missing button click
      current_time();

      //  stopwatch algo
      if (abs(second - last_second) >= 1) 
      {
        last_second = second;
            

        String stopwatch_time = String(stopwatch_hour) +
                              " : " + String(stopwatch_minute) +
                              " : " + String(stopwatch_second);
        lcd.clear();
        lcd_print(0, 0, "Stopwatch");
        lcd_print(0, 1, String(stopwatch_time));
        stopwatch_second++;
      }
      
      if (stopwatch_second > 59) 
      {
        stopwatch_second = 0;
        stopwatch_minute++;
      }
      else if (stopwatch_minute > 59) 
      {
        stopwatch_minute = 0;
        stopwatch_hour++;
      }
      else if (stopwatch_hour > 24) 
      {
        stopwatch_second, stopwatch_minute, stopwatch_hour = 0;
      }
      
  }

}

void countdown()
{

}

int set_value(int min_val, int max_val) {
  int value = 0;
  int last_counter = -1;
  counter = 0;

  while (true) {
    button.loop();
    if (button.isPressed())
      break;

    counter = constrain(counter, min_val, max_val);
    if (last_counter != counter) 
    {
          lcd_print(0, 1, "  ");
          lcd_print(0, 1, String(counter));
          last_counter = counter;
     }
  }
  value = counter;
  counter = 0;
  last_counter = -1;
  return value;
}

// void play_buzzer(int frequency, int duration) {
//   tone(buzzer_pin, frequency);
//   delay(duration);
//   noTone(buzzer_pin);
// }