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

const int buzzerPin = 10;
const int redLed = 11;
const int yelLed = 12;
const int grnLed = 13;
const int armSwitch = A0;
const int armButton = A2;
const int timerButton = A4;
const int timerDuration = 300000;

const byte ROW_NUM = 4;
const byte COLUMN_NUM = 4;

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};
byte pin_column[COLUMN_NUM] = {5, 4, 3, 2};

Keypad keypad = Keypad(makeKeymap(keys), pin_rows, pin_column, ROW_NUM, COLUMN_NUM);
LiquidCrystal_I2C lcd(0x27, 20, 4);

int defuseCode[] = {1, 2, 3, 4}; // Set defuse code here
int defuseCodeLength = 4;
int enteredCode[4];
int codeIndex = 0;
bool armed = false;
unsigned long countdownStartTime = 0;
unsigned long countdownDuration = timerDuration;
bool timerSetMode = false;

void setup() {
  Serial.begin(9600);
  lcd.init();
  lcd.backlight();
  pinMode(buzzerPin, OUTPUT);
  pinMode(redLed, OUTPUT);
  pinMode(yelLed, OUTPUT);
  pinMode(grnLed, OUTPUT);
  pinMode(armSwitch, INPUT_PULLUP);
  pinMode(armButton, INPUT_PULLUP);
  pinMode(timerButton, INPUT_PULLUP);
}

void loop() {
  if (!armed) {
    lcd.clear();
    lcd.setCursor(0, 0);
    lcd.print("System Safe");
    delay(500);
    if (digitalRead(timerButton) == LOW) {
      setTimer();
    }
  }
  else {
    checkArming(); // Check if key is turned and arm button is pressed
    updateCountdown();

    char key = keypad.getKey();

    if (key) {
      Serial.println(key);

      if (key == '#') {
        checkCode(); // Check entered code when # is pressed
      } else if (key == '*') {
        enterTimerSetMode(); // Enter timer set mode when * is pressed
      } else {
        //Append the entered digit to the code.
        enteredCode[codeIndex] = key - '0';
        codeIndex = (codeIndex + 1) % defuseCodeLength;
      }
    }
  }
}


void checkArming() {
  static bool lastArmButtonState = HIGH; // Store the last state of the arm button
  bool currentArmButtonState = digitalRead(armButton);

  if (digitalRead(armSwitch) == LOW && currentArmButtonState == LOW && lastArmButtonState == HIGH) {
    // Key turned and arm button pressed
    armed = true;
    lcd.clear();
    lcd.setCursor(0, 0);
    lcd.print("System Armed!!");
    countdownStartTime = millis();
    delay(2000);
    lcd.clear();
  }

  lastArmButtonState = currentArmButtonState;
}

void checkCode() {
  for (int i = 0; i < defuseCodeLength; i++) {
    if (enteredCode[i] != defuseCode[i]) {
      //Incorrect code, sound the alarm
      activateAlarm();
      return;
    }
  }

  //Correct code, deactivate alarm
  deactivateAlarm();
}

void activateAlarm() {
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("ALARM ACTIVATED!!");
  digitalWrite(redLed, HIGH);
  digitalWrite(yelLed, LOW);
  digitalWrite(grnLed, LOW);
  tone(buzzerPin, 1000); // Sound alarm
  delay(5000); // Alarm duration
  resetSystem();
}

void deactivateAlarm() {
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("ALARM DEACTIVATED");
  digitalWrite(grnLed, HIGH);
  digitalWrite(yelLed, LOW);
  digitalWrite(redLed, LOW);
  noTone(buzzerPin); // Stop alarm
  delay(2000); // Display deactivated message for 2 seconds
  resetSystem();
}

void resetSystem() {
  lcd.clear();
  codeIndex = 0; // Reset code entry
  armed = false; // Disarm the system
  timerSetMode = false; // Exit timer set mode
  countdownDuration = timerDuration; // Reset countdown duration
}

void enterTimerSetMode() {
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("Set Timer (s): ");
  lcd.setCursor(0, 1);
  lcd.print("Press # to confirm");

  int timerValue = 0;
  while (timerSetMode) {
    char key = keypad.getKey();
    if (key) {
      if (key == '#') {
        //Confirm timer value
        timerSetMode = false;
        countdownDuration = timerValue * 1000; // Convert seconds to milliseconds
      } else if (key == '*') {
        // Exit timer set mode
        timerSetMode = false;
      } else {
        //Append entered digit to the timer value
        timerValue = timerValue * 10 + (key - '0');
        lcd.setCursor(0, 1);
        lcd.print("                "); // Clear previous timer value
        lcd.setCursor(0, 1);
        lcd.print(timerValue);
      }
    }
  }
}

void updateCountdown() {
  if (armed && !timerSetMode) {
    unsigned long currentTime = millis();
    unsigned long elapsedTime = currentTime - countdownStartTime;

    if (elapsedTime < countdownDuration) {
      unsigned long remainingTime = (countdownDuration - elapsedTime) / 1000; // Convert milliseconds to seconds
      lcd.setCursor(0, 0);
      lcd.print("Countdown: ");
      lcd.setCursor(0, 1);
      lcd.print(remainingTime);
    }
  }
}

void setTimer() {
  timerSetMode = true;
  enterTimerSetMode();
}