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

// Initialize RTC and LCD
RTC_DS3231 rtc;
LiquidCrystal_I2C lcd(0x27, 16, 2);  // I2C address 0x27, 16 columns, 2 rows

// Alarm time (initially set to an invalid value)
int alarmHour = -1;  // Will be set by user input
int alarmMinute = -1;  // Will be set by user input

// Pins
const int buzzerPin = 9;
const int ledPin = 11;

// Alarm state (whether the alarm is ringing or not)
bool alarmRinging = false;

void setup() {
  // Initialize the serial monitor for input
  Serial.begin(9600);
  while (!Serial);

  // Initialize the RTC
  if (!rtc.begin()) {
    lcd.print("RTC not found");
    while (1);
  }

  // Initialize the LCD
  lcd.begin(16, 2);
  lcd.backlight();

  // Set up pin modes
  pinMode(buzzerPin, OUTPUT);
  pinMode(ledPin, OUTPUT);

  // Display a welcome message
  lcd.clear();
  lcd.print("Alarm Clock");
  delay(2000);

  // Ask for alarm time input via serial
  lcd.clear();
  lcd.print("Set Alarm Time");
  lcd.setCursor(0, 1);
  lcd.print("HH:MM");
  delay(2000);

  // Prompt user to set the alarm time through serial
  Serial.println("Enter alarm time in HH:MM format (e.g., 07:30):");
}

void loop() {
  // Read current time from the RTC
  DateTime now = rtc.now();

  // Display the current time on LCD
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print(now.hour(), DEC);
  lcd.print(":");
  lcd.print(now.minute(), DEC);
  lcd.print(":");
  lcd.print(now.second(), DEC);

  // Check if the alarm time has been set
  if (alarmHour != -1 && alarmMinute != -1) {
    // Check if the current time matches the alarm time
    if (now.hour() == alarmHour && now.minute() == alarmMinute && now.second() == 0) {
      triggerAlarm();
    }
  }

  // Listen for user input on the serial monitor to set alarm time or turn off the alarm
  if (Serial.available() > 0) {
    String input = Serial.readStringUntil('\n');  // Read input from serial
    input.trim();  // Remove any extra spaces or newlines

    // Check if the input is in the correct format (HH:MM) to set alarm time
    if (input.length() == 5 && input[2] == ':') {
      int hour = input.substring(0, 2).toInt();
      int minute = input.substring(3, 5).toInt();

      if (hour >= 0 && hour < 24 && minute >= 0 && minute < 60) {
        alarmHour = hour;
        alarmMinute = minute;

        // Confirm the new alarm time
        lcd.clear();
        lcd.print("Alarm Set to:");
        lcd.setCursor(0, 1);
        lcd.print(alarmHour);
        lcd.print(":");
        lcd.print(alarmMinute);
        delay(2000);
      }
      else {
        // Invalid time input
        lcd.clear();
        lcd.print("Invalid time");
        delay(1000);
      }
    }
    // Check if the user wants to turn off the alarm
    else if (input.equalsIgnoreCase("off") && alarmRinging) {
      stopAlarm();
    }
    else {
      // Invalid input
      lcd.clear();
      lcd.print("Invalid input");
      delay(1000);
    }
  }

  delay(1000);
}

void triggerAlarm() {
  // If the alarm is already ringing, do nothing
  if (alarmRinging) return;

  // Set alarm state to ringing
  alarmRinging = true;

  // Trigger buzzer and LED
  digitalWrite(buzzerPin, HIGH);  // Turn on buzzer
  digitalWrite(ledPin, HIGH);     // Turn on LED
  lcd.clear();
  lcd.print("ALARM RINGING!");

  // Display message to user for turning off the alarm
  lcd.setCursor(0, 1);
  lcd.print("Type 'off' to stop");

  // Print message to serial monitor
  Serial.println("ALARM is ringing! Type 'off' in the serial monitor to stop the alarm.");

  // No delay here. The alarm will keep ringing until the user stops it.
}

void stopAlarm() {
  // Stop buzzer and LED
  digitalWrite(buzzerPin, LOW);
  digitalWrite(ledPin, LOW);

  // Reset the alarm state
  alarmRinging = false;

  // Clear the LCD
  lcd.clear();
  lcd.print("Alarm Off");
  delay(2000);
}