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

LiquidCrystal_I2C lcd(0x27, 16, 2);

const byte rows = 4;
const byte columns = 4;
String correct_pass = "123456";
int buttonPin = 2;
int unlockPin = 3;
int warningPin = 4;

char keys[rows][columns] =
{
  {'1', '2', '3', 'A'},
  {'4', '5', '6', 'B'},
  {'7', '8', '9', 'C'},
  {'*', '0', '#', 'D'},
};
 
byte rowPins[rows] = {5, 6, 7, 8};
byte columnPins[columns] = {9, 10, 11, 12};

Keypad keypad = Keypad(makeKeymap(keys), rowPins, columnPins, rows, columns);

char read_character()
{
  char key = keypad.getKey();
  if(key) return key;
  return '\0';
}

bool check_password(int size = 6)
{
  String pass = "";
  char key = '\0';
  int count = 3;
  int temp_size = size;
  lcd.setCursor(5,1);
  while(count)
  {
    while(temp_size)
    {
      key = read_character();
      if(key != '\0' && key != 'A')
      {
        Serial.println(key);
        lcd.print(key);
        pass += String(key);
        key = '\0';
        temp_size--;
      }
      if(key == 'A')
      {
        temp_size = size;
        pass = "";
        lcd.setCursor(5,1);
        lcd.print("      ");
        lcd.setCursor(5,1);
        Serial.println("Reset enter password...");
      }
    }
    if(pass == correct_pass) break;
    else
    {
      pass = "";
      count--;
      temp_size = size;
      if(count)
      {
        Serial.println("Failed........");
        Serial.println("You have " + String(count) + " times for enter password.");
        Serial.println("You must wait 3 seconds.");
        delay(3000);
        Serial.println("----------------------------------------------------");
        Serial.println("Enter password agian.....");
        lcd.setCursor(5,1);
        lcd.print("      ");
        lcd.setCursor(5,1);
      }
    }
  }
  if(count) return true;
  return false;
}

void control_output(int pin)
{
  for(int i=0;i<3;i++)
  {
    digitalWrite(pin, 1);
    delay(500);
    digitalWrite(pin, 0);
    delay(500);
  }
}

void setup() {
  Serial.begin(9600);
  lcd.init();
  lcd.backlight();
  pinMode(buttonPin, INPUT);
  pinMode(unlockPin, OUTPUT);
  pinMode(warningPin, OUTPUT);
  lcd.clear();
  lcd.print("Start.");
  delay(500);
  lcd.clear();
  lcd.print("Start..");
  delay(500);
  lcd.clear();
  lcd.print("Start...");
  delay(500);
  lcd.clear();
  lcd.print("Start....");
  delay(500);
  lcd.clear();
  Serial.println("PRESS THE BUTTON IF YOU WANT TO UNLOCK........");
}

void loop() {  
  if(!digitalRead(buttonPin))
  {
    Serial.println("PRESS BUTTON");
    while(!digitalRead(buttonPin))
    {
      Serial.println("Please release button.........");
      delay(500);
    }
    Serial.println("RELEASE BUTTON");
    Serial.println("Enter your password........");
    lcd.setCursor(1,0);
    lcd.print("ENTER PASSWORD");
    if(check_password(6))
    {
      lcd.clear();
      lcd.setCursor(5,0);//-----Unlock------
      lcd.print("Unlock");
      lcd.setCursor(4,1);//-----Success-----
      lcd.print("Successs");
      Serial.println("------------------------------------------------");
      Serial.println("Unlock success...........");
      Serial.println("------------------------------------------------");
      control_output(unlockPin);
      lcd.clear();
    }
    else
    {
      lcd.clear();
      lcd.setCursor(5,0);//-----Unlock------
      lcd.print("Unlock");
      lcd.setCursor(5,1);//-----Failed-----
      lcd.print("Failed");
      Serial.println("------------------------------------------------");
      Serial.println("Unlock failed...........");
      Serial.println("------------------------------------------------");
      control_output(warningPin);
      lcd.clear();
    }
    Serial.println("PRESS THE BUTTON IF YOU WANT TO CONTINUE UNLOCKING...............");
  }
  delay(100);
}