#include <Wire.h>
#include <LiquidCrystal_I2C.h>
#include <Keypad.h>
#include <ESP32Servo.h>

LiquidCrystal_I2C lcd(0x27, 16, 2);

Servo doorServo;

// ---------------- PINS ----------------
int servoPin = 25;
int buzzerPin = 15;

// ---------------- KEYPAD ----------------
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] = {2,4,16,17};
byte colPins[COLS] = {5,18,19,23};

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

// ---------------- SECURITY ----------------
String userPIN = "123456";
String adminPIN = "999999";

String inputPIN = "";


int wrongAttempts = 0;
const int maxAttempts = 3;

bool lockedOut = false;
unsigned long lockStart = 0;
const unsigned long lockTime = 5000;

bool adminMode = false;

unsigned long unlockStart = 0;
bool doorUnlocked = false;

void setup() {

  Serial.begin(115200);
  Wire.begin(21,22);

  lcd.init();
  lcd.backlight();
  lcd.print("Enter 6-digit");
  lcd.setCursor(0,1);
  lcd.print("PIN:");

  doorServo.attach(servoPin);
  doorServo.write(0);

  pinMode(buzzerPin, OUTPUT);



  Serial.println("System Started");
}

void loop() {

  handleLockout();
  handleAutoLock();
  handleKeypad();


  delay(5);
}

// ---------------- KEYPAD ----------------
void handleKeypad() {

  char key = keypad.getKey();
  if (!key || lockedOut) return;

  processInput(key);
}


// ---------------- PROCESS INPUT ----------------
void processInput(char key) {

  if (key == '*') {
    inputPIN = "";
    resetLCD();
    return;
  }

  if (key == '#') {
    processPIN(inputPIN);
    inputPIN = "";
    return;
  }

  if (isdigit(key) && inputPIN.length() < 6) {
    inputPIN += key;
    lcd.setCursor(inputPIN.length()-1,1);
    lcd.print("*");
  }
}

// ---------------- PROCESS PIN ----------------
void processPIN(String entered) {

  lcd.clear();

  if (adminMode) {
    if (entered.length() == 6) {
      userPIN = entered;
      adminMode = false;
      lcd.print("PIN Updated");
      Serial.println("LOG: PIN Changed by Admin");
      delay(1500);
      resetLCD();
    }
    return;
  }

  if (entered == userPIN) {

    lcd.print("Access Granted");
    Serial.println("LOG: Door Unlocked");

    wrongAttempts = 0;
    unlockDoor();

  } 
  else if (entered == adminPIN) {

    adminMode = true;
    lcd.print("Admin Mode");
    lcd.setCursor(0,1);
    lcd.print("New PIN:");
    Serial.println("LOG: Admin Access");

  } 
  else {

    wrongAttempts++;
    lcd.print("Wrong PIN");
    lcd.setCursor(0,1);
    lcd.print("Attempts:");
    lcd.print(wrongAttempts);
    lcd.print("/");
    lcd.print(maxAttempts);

    Serial.println("LOG: Failed Attempt");

    beep(3);

    if (wrongAttempts >= maxAttempts) {
      activateLockout();
    }

    delay(1500);
    resetLCD();
  }
}

// ---------------- UNLOCK ----------------
void unlockDoor() {

  doorServo.write(90);
  doorUnlocked = true;
  unlockStart = millis();
  beep(1);
}

// ---------------- AUTO LOCK ----------------
void handleAutoLock() {

  if (doorUnlocked && millis() - unlockStart >= 5000) {
    doorServo.write(0);
    doorUnlocked = false;
    resetLCD();
  }
}

// ---------------- LOCKOUT ----------------
void activateLockout() {

  lockedOut = true;
  lockStart = millis();

  lcd.clear();
  lcd.print("LOCKED 5 SEC");

  Serial.println("LOG: System Lockout");
  beep(1);
}

void handleLockout() {

  if (lockedOut && millis() - lockStart >= lockTime) {
    lockedOut = false;
    wrongAttempts = 0;
    resetLCD();
  }
}

// ---------------- UTILITIES ----------------
void beep(int times) {
  for(int i=0;i<times;i++){
    digitalWrite(buzzerPin, HIGH);
    delay(150);
    digitalWrite(buzzerPin, LOW);
    delay(150);
  }
}

void resetLCD() {
  lcd.clear();
  lcd.print("Enter 6-digit");
  lcd.setCursor(0,1);
  lcd.print("PIN:");
}