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

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

#define RED_LED   12
#define GREEN_LED 13
#define BLUE_LED  14
#define BUZZER    27

const byte ROWS = 4;
const byte COLS = 4;
char keys[ROWS][COLS] = {
  {'1','2','3','A'},
  {'4','5','6','B'},
  {'7','8','9','C'},
  {'*','0','#','D'}
};
byte rowPins[ROWS] = {19, 18, 5, 17};
byte colPins[COLS] = {16, 4, 2, 15};
Keypad keypad = Keypad(makeKeymap(keys), rowPins, colPins, ROWS, COLS);

String input = "";
String masterPIN = "1234";

void showMessage(String line1, String line2 = "") {
  display.clearDisplay();
  display.setCursor(0, 0);
  display.println(line1);
  if (line2 != "") display.println(line2);
  display.display();
}

void setup() {
  Serial.begin(115200);

  pinMode(RED_LED, OUTPUT);
  pinMode(GREEN_LED, OUTPUT);
  pinMode(BLUE_LED, OUTPUT);  // Optional
  pinMode(BUZZER, OUTPUT);

  digitalWrite(RED_LED, LOW);
  digitalWrite(GREEN_LED, LOW);
  digitalWrite(BLUE_LED, LOW);
  digitalWrite(BUZZER, LOW);

  Wire.begin(21, 22);  // SDA, SCL
  if (!display.begin(SSD1306_SWITCHCAPVCC, 0x3C)) {
    Serial.println("OLED init failed");
    while (1);
  }

  display.setTextSize(1);
  display.setTextColor(WHITE);
  showMessage("Smart Access", "System Ready");
  delay(2000);
  showMessage("Enter PIN or", "Scan RFID");
}

void loop() {
  char key = keypad.getKey();

  if (key) {
    if (key == '#') {
      checkPIN();
    } else if (key == '*') {
      input = "";
      showMessage("PIN Cleared");
      delay(1000);
      showMessage("Enter PIN or", "Scan RFID");
    } else {
      input += key;
      showMessage("Enter PIN:", input);
    }
  }

  if (Serial.available()) {
    String rfid = Serial.readStringUntil('\n');
    rfid.trim();
    if (rfid == "#RFID123") {
      grantAccess();
    } else {
      denyAccess();
    }
    input = "";
    showMessage("Enter PIN or", "Scan RFID");
  }
}

void grantAccess() {
  digitalWrite(GREEN_LED, HIGH);
  digitalWrite(RED_LED, LOW);
  digitalWrite(BUZZER, LOW);
  showMessage("Access Granted ✅");
  delay(3000);
  digitalWrite(GREEN_LED, LOW);
}

void denyAccess() {
  digitalWrite(RED_LED, HIGH);
  digitalWrite(GREEN_LED, LOW);
  for (int i = 0; i < 3; i++) {
    digitalWrite(BUZZER, HIGH);
    delay(200);
    digitalWrite(BUZZER, LOW);
    delay(200);
  }
  showMessage("Access Denied ❌");
  delay(2000);
  digitalWrite(RED_LED, LOW);
}

void checkPIN() {
  if (input == masterPIN) {
    grantAccess();
  } else {
    denyAccess();
  }
  input = "";
  showMessage("Enter PIN or", "Scan RFID");
}