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

// Define the LCD address and dimensions
LiquidCrystal_I2C lcd(0x27, 20, 4); // Change address if necessary

// Define the relay pin
const int relayPin = 10;
const int settingsButtonPin = 11;  // Push button for entering settings menu

// Define keypad size and keys
const byte ROWS = 4;  // Four rows
const byte COLS = 4;  // Four columns
char keys[ROWS][COLS] = {
  {'1', '2', '3', 'A'},
  {'4', '5', '6', 'B'},
  {'7', '8', '9', 'C'},
  {'*', '0', '#', 'D'}
};
byte rowPins[ROWS] = {9, 8, 7, 6}; // Connect to the row pinouts of the keypad
byte colPins[COLS] = {5, 4, 3, 2}; // Connect to the column pinouts of the keypad

// Create keypad instance
Keypad keypad = Keypad(makeKeymap(keys), rowPins, colPins, ROWS, COLS);

// Define a preset PIN code length (we'll store 4 digits)
const int PIN_LENGTH = 4;
String correctPIN = "";   // Declare correctPIN as a global variable
String inputPIN = "";
bool lockerUnlocked = false;

// Address in EEPROM to store the PIN
int eepromAddress = 0;

void setup() {
  // Initialize the LCD
  lcd.init();
  lcd.backlight();
  
  // Set relay pin and button pin as output/input
  pinMode(relayPin, OUTPUT);
  digitalWrite(relayPin, LOW); // Initially, the locker is locked (relay off)
  pinMode(settingsButtonPin, INPUT_PULLUP);  // Button with internal pull-up
  
  // Display welcome message
  lcd.setCursor(0, 0);
  lcd.print("Locker System");
  lcd.setCursor(0, 1);
  lcd.print("Enter PIN:");

  // Load the correct PIN from EEPROM
  correctPIN = readPINFromEEPROM();  // Fix: Initialize correctPIN from EEPROM
}

void loop() {
  char key = keypad.getKey();
  
  // Check if the settings button is pressed
  if (digitalRead(settingsButtonPin) == LOW) {
    enterSettingsMenu();  // Enter the settings menu when button is pressed
    delay(300);  // Debounce delay
  }

  if (key) {
    if (key == '#') {
      // When '#' is pressed, check the PIN
      if (inputPIN == correctPIN) {
        unlockLocker();
      } else {
        incorrectPIN();
      }
      inputPIN = "";  // Reset the input PIN
    } else if (key == '*') {
      // '*' to reset the input
      inputPIN = "";
      lcd.setCursor(0, 2);
      lcd.print("                "); // Clear the input field
      lcd.setCursor(0, 1);
      lcd.print("Enter PIN:      ");
    } else {
      // Add the pressed key to the inputPIN string
      inputPIN += key;
      lcd.setCursor(0, 2);
      lcd.print("PIN: " + inputPIN);
    }
  }
}

void unlockLocker() {
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("PIN Correct!");
  lcd.setCursor(0, 1);
  lcd.print("Locker Unlocked");

  digitalWrite(relayPin, HIGH);  // Unlock (turn relay on)
  lockerUnlocked = true;

  delay(5000); // Keep unlocked for 5 seconds
  lockLocker();
}

void lockLocker() {
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("Locker Locked");

  digitalWrite(relayPin, LOW);  // Lock (turn relay off)
  lockerUnlocked = false;

  delay(2000);
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("Locker System");
  lcd.setCursor(0, 1);
  lcd.print("Enter PIN:");
}

void incorrectPIN() {
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("Incorrect PIN!");
  
  delay(2000);
  
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("Locker System");
  lcd.setCursor(0, 1);
  lcd.print("Enter PIN:");
}

// Enter Settings Menu to change the PIN
void enterSettingsMenu() {
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("Change PIN:");

  String newPIN = "";

  while (newPIN.length() < PIN_LENGTH) {
    char key = keypad.getKey();
    if (key) {
      newPIN += key;
      lcd.setCursor(0, 1);
      lcd.print("New PIN: " + newPIN);
    }
  }

  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("Saving New PIN...");
  savePINToEEPROM(newPIN);
  correctPIN = newPIN;  // Fix: Store the new PIN in correctPIN

  delay(2000);
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("Locker System");
  lcd.setCursor(0, 1);
  lcd.print("Enter PIN:");
}

// Save the new PIN to EEPROM
void savePINToEEPROM(String pin) {
  for (int i = 0; i < PIN_LENGTH; i++) {
    EEPROM.write(eepromAddress + i, pin[i]);
  }
}

// Read the PIN from EEPROM
String readPINFromEEPROM() {
  String pin = "";
  for (int i = 0; i < PIN_LENGTH; i++) {
    pin += char(EEPROM.read(eepromAddress + i));
  }
  return pin;
}