// Detailed Alarm Clock with Keypad Control (fully commented)

#include <Wire.h>               // Include I²C library for RTC & LCD bus
#include <LiquidCrystal_I2C.h>  // Include I²C LCD library for 16×2 display
#include <RTClib.h>             // Include RTClib for DS3231 real-time clock
#include <Keypad.h>             // Include Keypad library to read matrix keypad

// Create RTC and LCD objects
RTC_DS3231 rtc;
LiquidCrystal_I2C lcd(0x27, 16, 2); // I2C address 0x27, 16 cols, 2 rows

// Pin connected to the buzzer (pin 10 chosen to avoid keypad pins)
const int buzzerPin = 10;

// Variables to hold the alarm time; not const so they can be updated via keypad
typedef uint8_t byte;
int alarmHour = 13;   // Default alarm hour (24‑hour format)
int alarmMinute = 15; // Default alarm minute
bool alarmTriggered = false; // Flag to ensure one‑shot alarm

// Keypad configuration: a 4×4 matrix
const byte ROWS = 4;
const byte COLS = 4;
char keys[ROWS][COLS] = {
  {'1','2','3','A'},  // Row 1
  {'4','5','6','B'},  // Row 2
  {'7','8','9','C'},  // Row 3
  {'*','0','#','D'}   // Row 4
};

// Map keypad rows and columns to Arduino pins (R1→9, R2→8, R3→7, R4→6)
byte rowPins[ROWS] = {9, 8, 7, 6};
// Map keypad columns to pins (C1→5, C2→4, C3→3, C4→2)
byte colPins[COLS] = {5, 4, 3, 2};

// Initialize the Keypad
Keypad keypad = Keypad(makeKeymap(keys), rowPins, colPins, ROWS, COLS);

// Variables for capturing user input and display timing
String inputTime = "";        // Holds HHMM digits when setting alarm
bool settingAlarm = false;      // Tracks whether we are in alarm‑setting mode
unsigned long lastUpdate = 0;   // Timestamp for periodic display updates

void setup() {
  Wire.begin();              // Start I2C bus (used by RTC & LCD)
  lcd.begin(16, 2);          // Initialize the LCD dimensions
  lcd.backlight();           // Turn on LCD backlight

  pinMode(buzzerPin, OUTPUT);
  digitalWrite(buzzerPin, LOW); // Ensure buzzer is off initially

  // Initialize RTC; halt if DS3231 not found
  if (!rtc.begin()) {
    lcd.print("RTC not found!");
    while (1);
  }

  // Show welcome message then prompt for alarm
  lcd.print("Welcome 7oka");
  delay(4200);               // Give user time to read


  lcd.clear();
  lcd.print("Press A: Alarm");
  delay(4200);               // Give user time to read
  lcd.clear();
}

void loop() {
  // 1) Handle keypad input first, so we can switch modes immediately
  char key = keypad.getKey();
  if (key) {
    // If 'A' pressed, enter alarm‑setting mode
    if (key == 'A') {
      settingAlarm = true;
      inputTime = "";      // Clear any previous input
      lcd.clear();
      lcd.print("Set Alarm HHMM:");

    } 
    // If '#' pressed, confirm the 4‑digit input
    else if (key == '#') {
      if (inputTime.length() == 4) {
        // Parse the two‑digit hour and minute
        alarmHour   = inputTime.substring(0, 2).toInt();
        alarmMinute = inputTime.substring(2, 4).toInt();
        alarmTriggered = false; // Reset trigger for new alarm
        
        // Show confirmation
        lcd.clear();
        lcd.print("Alarm Set:");
        lcd.setCursor(0, 1);
        // Print HH:MM with leading zeros
        if (alarmHour < 10) lcd.print('0');
        lcd.print(alarmHour);
        lcd.print(":");
        if (alarmMinute < 10) lcd.print('0');
        lcd.print(alarmMinute);
        delay(2000);
      }
      settingAlarm = false;     // Exit setting mode
      lcd.clear();
    } 

 // If 'C' pressed in setting mode, delete last character (backspace)
    else if (settingAlarm && key == 'C' && inputTime.length() > 0) {
      inputTime.remove(inputTime.length() - 1); // Remove last char
      // Update display: clear second line and reprint inputTime
      lcd.setCursor(0, 1);
      lcd.print("    ");               // Clear 4-char field
      lcd.setCursor(0, 1);
      lcd.print(inputTime);
    }

    // If in setting mode and digit pressed, append to input
    else if (settingAlarm && isDigit(key) && inputTime.length() < 4) {
      inputTime += key;
      // Echo the digit on the second line
      lcd.setCursor(inputTime.length() - 1, 1);
      lcd.print(key);
    }
  }

  // 2) Update time/date display every 1s if not in setting mode
  if (!settingAlarm && millis() - lastUpdate > 1000) {
    lastUpdate = millis();        // Reset timer
    DateTime now = rtc.now();     // Read current time

    // First line: show HH:MM:SS
    lcd.setCursor(0, 0);
    lcd.print("Time: ");
    if (now.hour()   < 10) lcd.print('0');
    lcd.print(now.hour());
    lcd.print(':');
    if (now.minute() < 10) lcd.print('0');
    lcd.print(now.minute());
    lcd.print(':');
    if (now.second() < 10) lcd.print('0');
    lcd.print(now.second());

    // Second line: show DD/MM/YYYY
    lcd.setCursor(0, 1);
    lcd.print("Date: ");
    if (now.day()   < 10) lcd.print('0');
    lcd.print(now.day());
    lcd.print('/');
    if (now.month() < 10) lcd.print('0');
    lcd.print(now.month());
    lcd.print('/');
    lcd.print(now.year());
  }

  // 3) Alarm trigger: check every loop for exact match at second 0
  DateTime now2 = rtc.now();
  if (!alarmTriggered &&
      now2.hour()   == alarmHour &&
      now2.minute() == alarmMinute &&
      now2.second() == 0) {
    alarmTriggered = true;        // Prevent re-trigger
    digitalWrite(buzzerPin, HIGH);
    delay(10000);                 // Buzz for 10s
    digitalWrite(buzzerPin, LOW);
  }
}