#include <Wire.h>
#include <LiquidCrystal_I2C.h>

// Initialize the LCD with the correct I2C address and dimensions
LiquidCrystal_I2C lcd(0x27, 16, 2); // Change 0x27 to your LCD's I2C address

// Pin definitions
const int startButtonPin = 3;  // Button to start the timer
const int setButtonPin = 2;    // Button to change the timer setting
const int alarmPin = 4;        // Alarm output (e.g., buzzer or LED)

// Timer variables
unsigned long timerDuration = 60 * 60 * 1000; // Default: 60 minutes in milliseconds
unsigned long remainingTime = timerDuration;
unsigned long startTime = 0;
bool timerRunning = false;
bool alarmTriggered = false;

// Timer options
const int timerOptions[] = {15, 30, 45, 60}; // Timer options in minutes
int currentTimerIndex = 3; // Default: 60 minutes (index 3)

void setup() {
  // Initialize LCD
  lcd.init();
  lcd.backlight();
  lcd.setCursor(0, 0);
  lcd.print("Timer: 60 min");
  lcd.setCursor(0, 1);
  lcd.print("Press to start");

  // Set pin modes
  pinMode(startButtonPin, INPUT_PULLUP);
  pinMode(setButtonPin, INPUT_PULLUP);
  pinMode(alarmPin, OUTPUT);

  // Initialize outputs
  digitalWrite(alarmPin, LOW);
}

void loop() {
  // Check if the set button is pressed to change the timer
  if (digitalRead(setButtonPin) == LOW) {
    delay(200); // Debounce delay
    changeTimer();
    while (digitalRead(setButtonPin) == LOW); // Wait for button release
  }

  // Check if the start button is pressed to start the timer
  if (digitalRead(startButtonPin) == LOW) {
    delay(200); // Debounce delay
    startTimer();
    while (digitalRead(startButtonPin) == LOW); // Wait for button release
  }

  // Update the countdown timer if it is running
  if (timerRunning) {
    updateCountdown();
  }

  // Check if the timer has expired
  if (timerRunning && remainingTime <= 0) {
    timerRunning = false;
    triggerAlarm();
  }
}

void changeTimer() {
  // Cycle through timer options
  currentTimerIndex = (currentTimerIndex + 1) % 4;
  timerDuration = timerOptions[currentTimerIndex] * 60 * 1000; // Convert minutes to milliseconds
  remainingTime = timerDuration;

  // Update the LCD display
  lcd.setCursor(0, 0);
  lcd.print("Timer: ");
  lcd.print(timerOptions[currentTimerIndex]);
  lcd.print(" min  ");

  // Reset the timer if it was running
  if (timerRunning) {
    timerRunning = false;
    lcd.setCursor(0, 1);
    lcd.print("Press to start");
  }
}

void startTimer() {
  if (!timerRunning && !alarmTriggered) {
    startTime = millis();
    timerRunning = true;
    lcd.setCursor(0, 1);
    lcd.print("Running...    ");
  }
}

void updateCountdown() {
  unsigned long elapsedTime = millis() - startTime;
  remainingTime = timerDuration - elapsedTime;

  // Display the remaining time on the LCD
  int minutes = remainingTime / 60000;
  int seconds = (remainingTime % 60000) / 1000;
  lcd.setCursor(0, 1);
  lcd.print("Time left: ");
  if (minutes < 10) lcd.print("0");
  lcd.print(minutes);
  lcd.print(":");
  if (seconds < 10) lcd.print("0");
  lcd.print(seconds);
  lcd.print("   ");
}

void triggerAlarm() {
  // Trigger the alarm
  digitalWrite(alarmPin, HIGH);
  alarmTriggered = true;

  // Display alarm message on LCD
  lcd.setCursor(0, 1);
  lcd.print("Alarm!        ");

  // Keep the alarm on until reset
  while (alarmTriggered) {
    if (digitalRead(startButtonPin) == LOW) {
      delay(200); // Debounce delay
      resetAlarm();
      while (digitalRead(startButtonPin) == LOW); // Wait for button release
    }
  }
}

void resetAlarm() {
  // Reset the alarm and timer
  digitalWrite(alarmPin, LOW);
  alarmTriggered = false;
  timerRunning = false;
  remainingTime = timerDuration;

  // Update the LCD display
  lcd.setCursor(0, 1);
  lcd.print("Press to start");
}