#include <Keypad.h>
#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>

// OLED setup
#define SCREEN_WIDTH 128
#define SCREEN_HEIGHT 64
#define OLED_RESET -1
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);

// Keypad setup
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

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

// Predefined PIN
String correctPIN = "1234";
String enteredPIN = "";

void setup() {
  // Initialize serial communication
  Serial.begin(9600);

  // Initialize OLED display
  if (!display.begin(SSD1306_SWITCHCAPVCC, 0x3C)) {
    Serial.println(F("SSD1306 allocation failed"));
    for (;;); // Halt
  }
  display.clearDisplay();
  display.setTextSize(1);
  display.setTextColor(WHITE);
  display.setCursor(0, 0);
  display.println("Manual Authentication");
  display.display();
  delay(2000);
}

void loop() {
  char key = keypad.getKey();
  if (key) { // If a key is pressed
    if (key == '#') { // '#' is the Enter key
      checkAuthentication();
    } else if (key == '*') { // '*' is the Clear key
      enteredPIN = "";
      updateDisplay("PIN Cleared");
    } else { // Add digit to PIN
      enteredPIN += key;
      updateDisplay("Enter PIN: " + enteredPIN);
    }
  }
}

void checkAuthentication() {
  if (enteredPIN == correctPIN) {
    updateDisplay("Access Granted");
    Serial.println("Access Granted");
  } else {
    updateDisplay("Access Denied");
    Serial.println("Access Denied");
  }
  enteredPIN = ""; // Reset PIN after checking
}

void updateDisplay(String message) {
  display.clearDisplay();
  display.setTextSize(1);
  display.setCursor(0, 0);
  display.println(message);
  display.display();
}