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

#define LCD_RS 7
#define LCD_EN 8
#define LCD_D4 9
#define LCD_D5 10
#define LCD_D6 11
#define LCD_D7 12
#define BUTTON_PIN 2
#define BUZZER_PIN 3

LiquidCrystal lcd(8, 9, 4, 5, 6, 7); // RS, EN, D4, D5, D6, D7

RTC_DS3231 rtc;

// Adjust this value according to your time zone offset
const int timeZoneOffset = 0; // For example, if you're in GMT+0, set it to 0

bool alarmTriggered = false;

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

  if (!rtc.begin()) {
    Serial.println("Couldn't find RTC");
    while (1);
  }

  pinMode(BUTTON_PIN, INPUT_PULLUP); // Configure button pin as input with pull-up resistor
  pinMode(BUZZER_PIN, OUTPUT); // Configure buzzer pin as output

  lcd.begin(16, 2); // Initialize the LCD with 16 columns and 2 rows
  lcd.clear(); // Clear the LCD screen
  
  lcd.print("Time: ");
}

void loop() {
  if (Serial.available() > 0) {
    setTimeOrAlarmFromSerial();
  }

  DateTime now = rtc.now() + TimeSpan(0, timeZoneOffset, 0, 0); // Adjust time for time zone offset

  // Convert hour to 12-hour format
  int hour12 = now.hour() % 12;
  if (hour12 == 0) {
    hour12 = 12; // Set 12 instead of 0 for 12 AM
  }

  // Determine AM/PM
  String ampm = now.hour() < 12 ? "AM" : "PM";

  lcd.setCursor(6, 0); // Move cursor to position (column 7, row 1)
  printDigits(hour12); // Print hour
  lcd.print(':');
  printDigits(now.minute()); // Print minute
  lcd.print(':');
  printDigits(now.second()); // Print second
  lcd.print(' ');
  lcd.print(ampm);

  lcd.setCursor(0, 1); // Move cursor to position (column 0, row 2)
  printDigits(now.day()); // Print day
  lcd.print('/');
  printDigits(now.month()); // Print month
  lcd.print('/');
  lcd.print(now.year()); // Print year

  if (alarmTriggered) {
    digitalWrite(BUZZER_PIN, HIGH); // Turn on buzzer
    if (digitalRead(BUTTON_PIN) == LOW) { // Check if button is pushed
      alarmTriggered = false; // Reset alarm triggered flag
      digitalWrite(BUZZER_PIN, LOW); // Turn off buzzer
      rtc.disableAlarm(1, DS3231_A1_Minute); // Disable the alarm
    }
  }

  delay(1000); // Update every second
}

void printDigits(int digits) {
  // Add leading 0 if the number is less than 10
  if (digits < 10)
    lcd.print('0');
  lcd.print(digits);
}

void setTimeOrAlarmFromSerial() {
  String input = Serial.readStringUntil('\n');
  if (input.startsWith("alarm ")) {
    input.remove(0, 6); // Remove "alarm " from the input string
    int hour, minute;
    char ampm[3];
    if (sscanf(input.c_str(), "%d:%d %2s", &hour, &minute, ampm) == 3) {
      if (strcmp(ampm, "AM") == 0 || strcmp(ampm, "PM") == 0) {
        hour = (hour % 12) + ((strcmp(ampm, "PM") == 0 && hour < 12) ? 12 : 0);
        rtc.writeSqwPinMode(DS3231_OFF); // Disable the SQW pin
        rtc.setAlarm1(DateTime(rtc.now().year(), rtc.now().month(), rtc.now().day(), hour, minute, 0), DS3231_A1_Hour);
        rtc.disableAlarm(1, DS3231_A1_Minute); // Enable alarm 1
        Serial.println("Alarm set successfully!");
        alarmTriggered = false; // Reset alarm triggered flag
      } else {
        Serial.println("Invalid time format. Please use AM or PM.");
      }
    } else {
      Serial.println("Invalid time format. Please use HH:MM AM/PM format.");
    }
  }
}