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

const int buzzerPin = 1;  // Connect to pin 12
const int redLed = 13;
const int grnLed = 11;
const int armSwitchPin = A0;    // Connect the arm key switch to pin 10
const int armButtonPin = A2;    // Connect the arm button to pin 11
const int timerButtonPin = A3;   // Connect the timer button to pin A0
const int timerDuration = 300000;  // Initial timer duration in milliseconds (5 minutes)

const byte ROW_NUM    = 4; // four rows
const byte COLUMN_NUM = 4; // four columns

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

Keypad keypad = Keypad(makeKeymap(keys), pin_rows, pin_column, ROW_NUM, COLUMN_NUM);
LiquidCrystal_I2C lcd(0x27, 20, 4);  // I2C address 0x27, 20 columns and 4 rows

int defuseCode[] = {1, 2, 3, 4}; // Set your 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.begin(20, 4);
  lcd.backlight();  // If your LCD has backlight control
  pinMode(buzzerPin, OUTPUT);
  pinMode(grnLed, OUTPUT);
  pinMode(redLed, OUTPUT);
  pinMode(armSwitchPin, INPUT_PULLUP);  // Use INPUT_PULLUP to avoid external pull-up resistor
  pinMode(armButtonPin, INPUT_PULLUP);  // Use INPUT_PULLUP to avoid external pull-up resistor
  pinMode(timerButtonPin, INPUT_PULLUP);
}

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

    char key = keypad.getKey();

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

      if (key == '#') {
        // Check the entered code when '#' is pressed
        checkCode();
      } else if (key == '*') {
        // Enter timer set mode when '*' is pressed
        enterTimerSetMode();
      } 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(armButtonPin);

  if (digitalRead(armSwitchPin) == LOW && currentArmButtonState == LOW && lastArmButtonState == HIGH) {
    // Key switch 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 the alarm
  deactivateAlarm();
}

void activateAlarm() {
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("ALARM ACTIVATED");
  digitalWrite(redLed, HIGH);
  tone(buzzerPin, 1000); // Sound the alarm
  delay(5000); // Alarm duration, change as needed
  resetSystem();
}

void deactivateAlarm() {
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("ALARM DEACTIVATED");
  digitalWrite(grnLed, LOW);
  noTone(buzzerPin); // Stop the alarm sound
  delay(2000); // Display the 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 the entered digit to the timer value
        timerValue = timerValue * 10 + (key - '0');
        lcd.setCursor(0, 1);
        lcd.print("                "); // Clear the 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, 2);
      lcd.print("Countdown: ");
      lcd.print(remainingTime);
      lcd.print("s");
    } else {
      // Countdown finished, activate the alarm
      activateAlarm();
    }
  }
}

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