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

RTC_DS1307 rtc;
LiquidCrystal_I2C lcd(0x27, 16, 2);

const byte ROW_NUM = 4; // Number of rows in the keypad
const byte COLUMN_NUM = 4; // Number of columns in the keypad

char keys[ROW_NUM][COLUMN_NUM] = {
  {'1', '2', '3', 'A'},
  {'4', '5', '6', 'B'},
  {'7', '8', '9', 'C'},
  {'*', '0', '#', 'D'}
};

byte pin_rows[ROW_NUM] = {9, 8, 7, 6};    // Connect to the row pinouts of the keypad
byte pin_column[COLUMN_NUM] = {5, 4, 3, 2};  // Connect to the column pinouts of the keypad

int buzzerPin = 13;
DateTime alarmTime;
bool alarmEnabled = false;

void setup () {
  Serial.begin(9600);
  lcd.begin(16, 2);
  lcd.backlight();

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

  if (!rtc.isrunning()) {
    lcd.print("RTC is NOT running!");
  }
}

void loop () {
  checkKeypad();

  DateTime now = rtc.now();
  displayTime(now);

  if (alarmEnabled && now.hour() == alarmTime.hour() && now.minute() == alarmTime.minute()) {
    activateAlarm();
  }

  delay(1000);
}

void checkKeypad() {
  char key = getKey();

  if (key) {
    handleKeyPress(key);
    delay(500); // Debounce
  }
}

char getKey() {
  for (int i = 0; i < ROW_NUM; i++) {
    pinMode(pin_rows[i], OUTPUT);
    digitalWrite(pin_rows[i], LOW);

    for (int j = 0; j < COLUMN_NUM; j++) {
      if (digitalRead(pin_column[j]) == LOW) {
        delay(50);
        return keys[i][j];
      }
    }

    pinMode(pin_rows[i], INPUT);
  }

  return 0;
}

void handleKeyPress(char key) {
  switch (key) {
    case 'A':
      setAlarm();
      break;
    case 'B':
      disableAlarm();
      break;
    default:
      break;
  }
}

void setAlarm() {
  lcd.clear();
  lcd.print("Set Alarm");

  int hour = setDigit("Hour", 24);
  int minute = setDigit("Minute", 60);

  alarmTime = DateTime(alarmTime.year(), alarmTime.month(), alarmTime.day(), hour, minute, 0);
  alarmEnabled = true;

  lcd.clear();
  lcd.print("Alarm Set");
  delay(1000);
}

int setDigit(const char* label, int maxVal) {
  lcd.clear();
  lcd.print(label);

  int digit = -1;
  while (digit < 0 || digit >= maxVal) {
    char key = getKey();
    if (key >= '0' && key <= '9') {
      digit = key - '0';
      lcd.setCursor(0, 1);
      lcd.print(digit);
    }
  }

  delay(500);
  return digit;
}

void disableAlarm() {
  alarmEnabled = false;
  lcd.clear();
  lcd.print("Alarm Disabled");
  delay(1000);
}

void displayTime(DateTime now) {
  lcd.clear();
  lcd.print(now.toString("yyyy-MM-dd"));
  lcd.setCursor(0, 1);
  lcd.print(now.toString("HH:mm:ss"));
}

void activateAlarm() {
  tone(buzzerPin, 1000);
  delay(5000);
  noTone(buzzerPin);
  disableAlarm();
}