const byte ROW_NUM    = 4; 
const byte COLUMN_NUM = 4; 


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


byte pin_rows[ROW_NUM] = {9, 8, 7, 6};
byte pin_column[COLUMN_NUM] = {5, 4, 3, 2};


const int lockServoPin = 10;  
const int greenLED = 12;
const int redLED = 11;
const int buzzer = 13;


const String correctPassword = "1234";
String inputPassword = ""; 

void setup() {
  
  pinMode(greenLED, OUTPUT);
  pinMode(redLED, OUTPUT);
  pinMode(buzzer, OUTPUT);
  
  
  pinMode(lockServoPin, OUTPUT);
  
  
  for (byte i = 0; i < ROW_NUM; i++) {
    pinMode(pin_rows[i], OUTPUT);
    digitalWrite(pin_rows[i], HIGH);  
  }
  
  for (byte j = 0; j < COLUMN_NUM; j++) {
    pinMode(pin_column[j], INPUT_PULLUP);  
  }

  
  digitalWrite(greenLED, LOW);
  digitalWrite(redLED, LOW);
  
  Serial.begin(9600);  
}

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

  
  if (key) {
    if (key == '#') {
     
      if (inputPassword == correctPassword) {
        
        unlock();
      } else {
        
        lock();
      }
      inputPassword = ""; 
    } else if (key == '*') {
      
      inputPassword = "";
    } else {
      
      inputPassword += key;
    }
    
    Serial.println(inputPassword);  
  }
}


char getKey() {
  for (byte row = 0; row < ROW_NUM; row++) {
    
    digitalWrite(pin_rows[row], LOW);
    
    
    for (byte col = 0; col < COLUMN_NUM; col++) {
      if (digitalRead(pin_column[col]) == LOW) {
        delay(200);  
        while (digitalRead(pin_column[col]) == LOW); 
        digitalWrite(pin_rows[row], HIGH); 
        return keys[row][col]; 
      }
    }
    
  
    digitalWrite(pin_rows[row], HIGH);
  }
  return 0; 
}


void unlock() {
  digitalWrite(greenLED, HIGH);  
  digitalWrite(redLED, LOW);    
  
  tone(buzzer, 1000, 500);       
  
  
  analogWrite(lockServoPin, 128); 
  
  delay(1000); 

  
}


void lock() {
  digitalWrite(greenLED, LOW);   
  digitalWrite(redLED, HIGH);    
  
  tone(buzzer, 500, 500);        
  
  
  analogWrite(lockServoPin, 255);  
  
  delay(1000); 
  noTone(buzzer);                
}