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

RTC_DS1307 rtc;
LiquidCrystal_I2C lcd(0x27, 20, 4);

//  encoder variables
byte clk = 2;
byte dt = 3;
byte sw = 4;
byte buzzer_pin = 5;

ezButton button(sw);

//  counting rotations
int counter = 0;
int prev_counter = -1;
int flag = 1;

// Date and time
int year = 0, month = 0, day = 0;
int hour = 0, minute = 0, second = 0;

int alarm_hours = 0, alarm_minutes = 0;

void setup() {
  lcd.init();
  lcd.clear(); 
  lcd.backlight();
  
  if (!rtc.begin()) {
    Serial.println("RTC not initialised");
    while (true);
  }
  lcd_print(0, 0, "RTC found");
  delay(500);

  attachInterrupt(digitalPinToInterrupt(clk), encoder, FALLING);
  button.setDebounceTime(25);
}

void encoder() {
  prev_counter = counter;
  if (digitalRead(dt) == HIGH) counter++;
  else counter--;
  flag = 1;
}

void mode_selector() {
  counter = constrain(counter, 0, 3);
  if (prev_counter != counter  &&  flag  ==  1) {
    if (counter  ==  0) {
      lcd.clear();
      lcd_print(0, 1, "Date and Time?");
    }
    else if (counter  ==  1) {
      lcd.clear();
      lcd_print(0, 1, "Set Alarm?");
    }
    else if (counter  ==  2) {
      lcd.clear();
      lcd_print(0, 1, "Stopwatch?");
    }
    else if (counter  ==  3) {
      lcd.clear();
      lcd_print(0, 1, "Countdown Timer?");
    }
    flag = 0;
  }
}

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

  currentTime();
  if (alarm_minutes == minute && alarm_hours == hour) {
    playBuzzer(1000, 500);
    alarm_hours, alarm_minutes = 0;
  }

  delay(50);
}

void select_mode(){
  if (counter  ==  0) show_time();
  else if (counter  ==  1) set_alarm();
  else if (counter  ==  2) stopwatch();
  else countdown();
}

void currentTime() {
  DateTime current = rtc.now();
  year = current.year();
  month = current.month();
  day = current.day();
  hour = current.hour();
  minute = current.minute();
  second = current.second();
}

void show_time() {
  lcd.clear();
  lcd_print(1, 0, "Date and Time:");
  lcd_print(0, 1, "Date:-");
  lcd_print(0, 2, "Time:-");
  while (true) {
    button.loop();
    if (button.isPressed()) {
      lcd.clear();
      prev_counter = -1;
      flag = 1;
      break;
    }
    currentTime();
    String currentDate = String(day) + "/" + String(month) + "/" + String(year);
    String currentTime = String(hour) + ":" + String(minute) + ":" + String(second);
    
    lcd_print(7, 1, "         ");
    lcd_print(7, 2, "         ");
    lcd_print(7, 1, currentDate);
    lcd_print(7, 2, currentTime);
    delay(50);
  }
}
 
void set_alarm() {
  lcd.clear();
  lcd_print(0, 0, "Alarm");
  lcd_print(0, 1, "Enter hours: ");
  alarm_hours = set_value(0, 23);

  lcd.clear();
  lcd_print(0, 0, "Alarm");
  lcd_print(0, 1, "Enter minutes: ");
  alarm_minutes = set_value(0, 59);

  lcd.clear();
  lcd_print(0, 1, "Alarm set successfully");
  delay(500);
}

void stopwatch(){
  int stopwatch_hour, stopwatch_minute, stopwatch_second = 0;
  while (true) {
    button.loop();
    if (button.isPressed()) {
      lcd.clear();
      prev_counter = -1;
      flag = 1;
      break;
    }

    String stopwatch_time = String(stopwatch_hour) + ":" + String(stopwatch_minute) + ":" + String(stopwatch_second);
    lcd.clear();
    lcd_print(0, 0, "Stopwatch:");
    lcd_print(0, 1, 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 > 23) {
      stopwatch_hour, stopwatch_minute, stopwatch_second = 0;
    }
  }
}

void countdown() {
  int cd_mins, cd_secs = 0;

  lcd.clear();
  lcd_print(0, 0, "Countdown Timer");
  lcd_print(0, 1, "Enter minutes: ");
  cd_mins = set_value(0, 59);

  lcd.clear();
  lcd_print(0, 0, "Countdown Timer");
  lcd_print(0, 1, "Enter seconds: ");
  cd_secs = set_value(0, 59);

  while (cd_mins != 0 || cd_secs != 0) {
    lcd.clear();
    lcd_print(0, 1, "Countdown Timer:");
    String msg = String(cd_mins) + ":" + String(cd_secs);
    lcd_print(0, 2, msg);

    if (cd_secs == 0) {
      if (cd_mins !=0 ) {
        cd_secs = 59;
        cd_mins--;
      }
    }
    cd_secs--;
    delay(1000);
  }

  lcd.clear();
  lcd_print(0, 0, "Countdown Over");
  playBuzzer(2000, 3000);
}

int set_value(int minVal, int maxVal) {
  int value = 0;
  counter = 0;

  while(true) {
    button.loop();
    if (button.isPressed()) break;
    counter = constrain(counter, minVal, maxVal);
    lcd_print(0, 2, "  ");
    lcd_print(0, 2, String(counter));
  }

  value = counter;
  return value;
}

void playBuzzer(int freq, int dur) {
  tone(buzzer_pin, freq);
  delay(dur);
  noTone(buzzer_pin);
}

void lcd_print(int x, int y, String message) {
  lcd.setCursor(x, y);
  lcd.print(message);
}