// === Pin Definitions ===
int rowPins[4] = {2, 3, 4, 5};
int colPins[4] = {6, 7, 8, 9};

char keys[4][4] = {
  {'1','2','3','A'},
  {'4','5','6','B'},
  {'7','8','9','C'},
  {'*','0','#','D'}
};

int servoPin = 10;
int buzzerPin = 11;
int greenLED = 12;
int redLED = 13;

int trigPin = A2;
int echoPin = A3;

String password = "73737*A";
String entered = "";
int pos = 0;

void setup() {
  Serial.begin(9600);

  for (int i = 0; i < 4; i++) pinMode(rowPins[i], OUTPUT);
  for (int j = 0; j < 4; j++) pinMode(colPins[j], INPUT_PULLUP);

  pinMode(servoPin, OUTPUT);
  pinMode(buzzerPin, OUTPUT);
  pinMode(greenLED, OUTPUT);
  pinMode(redLED, OUTPUT);
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);

  lock();  // Start locked
}

void loop() {
  // Ultrasonic Distance Check
  digitalWrite(trigPin, LOW); delayMicroseconds(2);
  digitalWrite(trigPin, HIGH); delayMicroseconds(10);
  digitalWrite(trigPin, LOW);

  long duration = pulseIn(echoPin, HIGH);
  long distance = duration * 0.034 / 2;

  Serial.print("Distance: ");
  Serial.print(distance);
  Serial.println(" cm");

  if (distance < 80) {
    char key = getKey();
    if (key != ' ') {
      beepKey();
      Serial.print("Key: ");
      Serial.println(key);

      if (key == '#') {
        if (entered == password) {
          Serial.println("✅ Access Granted");
          ledSuccess();            // Green LED + melody (5 sec)
          unlock();                // Unlock servo
          delay(3000);
          lock();                  // Re-lock
        } else {
          Serial.println("❌ Access Denied");
          ledErrorWithAlarm();     // 12-sec red LED & buzzer
        }
        entered = "";
      } else {
        entered += key;
      }
    }
  }

  delay(300);
}

// === Keypad Scanning ===
char getKey() {
  for (int r = 0; r < 4; r++) {
    digitalWrite(rowPins[r], LOW);
    for (int c = 0; c < 4; c++) {
      if (digitalRead(colPins[c]) == LOW) {
        delay(200);
        while (digitalRead(colPins[c]) == LOW);
        digitalWrite(rowPins[r], HIGH);
        return keys[r][c];
      }
    }
    digitalWrite(rowPins[r], HIGH);
  }
  return ' ';
}

// === Servo Motor Control ===
void unlock() {
  for (pos = 0; pos <= 90; pos += 5) {
    int pwm = map(pos, 0, 180, 544, 2400);
    analogWriteServo(servoPin, pwm);
    delay(15);
  }
}

void lock() {
  for (pos = 90; pos >= 0; pos -= 5) {
    int pwm = map(pos, 0, 180, 544, 2400);
    analogWriteServo(servoPin, pwm);
    delay(15);
  }
}

void analogWriteServo(int pin, int pulseWidth) {
  for (int i = 0; i < 10; i++) {
    digitalWrite(pin, HIGH);
    delayMicroseconds(pulseWidth);
    digitalWrite(pin, LOW);
    delay(20 - pulseWidth / 1000);
  }
}

// === Key Press Feedback ===
void beepKey() {
  tone(buzzerPin, 1000, 100);
  delay(150);
}

// ✅ Feel-good Melody + Green LED blink (5 seconds)
void ledSuccess() {
  int melody[] = {523, 587, 659, 698, 784, 880, 988, 1047};
  int durations[] = {300, 300, 300, 300, 300, 300, 300, 500};

  for (int i = 0; i < 8; i++) {
    digitalWrite(greenLED, HIGH);
    tone(buzzerPin, melody[i]);
    delay(durations[i]);
    digitalWrite(greenLED, LOW);
    noTone(buzzerPin);
    delay(100);
  }
}

// ❌ Red LED + Buzzer for 12 seconds
void ledErrorWithAlarm() {
  unsigned long startTime = millis();
  while (millis() - startTime < 12000) {
    tone(buzzerPin, 2000);
    digitalWrite(redLED, HIGH);
    delay(300);
    digitalWrite(redLED, LOW);
    delay(300);
  }
  noTone(buzzerPin);
}