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

const uint8_t ROWS = 4;
const uint8_t COLS = 4;
char keys[ROWS][COLS] = {
  { '1', '2', '3', 'A' },
  { '4', '5', '6', 'B' },
  { '7', '8', '9', 'C' },
  { '*', '0', '#', 'D' }
};

uint8_t colPins[COLS] = { 5, 4, 3, 2 }; // Pins connected to C1, C2, C3, C4
uint8_t rowPins[ROWS] = { 9, 8, 7, 6 }; // Pins connected to R1, R2, R3, R4

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


#define I2C_ADDR    0x27
#define LCD_COLUMNS 20
#define LCD_LINES   4
LiquidCrystal_I2C lcd(I2C_ADDR, LCD_COLUMNS, LCD_LINES);


void setup() {
  Serial.begin(115200);
  lcd.init();
  lcd.backlight();
  lcd.setCursor(3, 0);
  
  unlocked();
}
bool isDoorLocked=false;


void loop() {
if(isLocked()){
locked();
}else{
unlocked();
}
}

String newpass="";
String savedPass="";
bool isPassSet=false;

String setPass(){
  lcd.clear();
  lcd.setCursor(5, 0);
  lcd.print("Enter Pass");
  lcd.setCursor(7, 1);
  lcd.print("<    >");
  lcd.setCursor(8, 1);
  while (newpass.length() < 4) {
  char key = keypad.getKey();
  if (key<='9' && key>='0') {
    lcd.print(key);
    newpass+=key;
  }
  }
  if(newpass.length()==4 ){
    isPassSet=true;
  }
  return newpass;
}

bool isSet(){
 if(isPassSet){
   return true;
 }

  return false;
}

void checkPass(String pass){
    lcd.setCursor(0, 2);
if(pass==savedPass){
  unlocked();
}else if(pass!=savedPass){
  locked();
}
}

bool isLocked(){
if(isDoorLocked){
   return true;
 }
  return false;
}

void locked(){
  isDoorLocked=true;
    lcd.clear();
    lcd.setCursor(1,1);
    lcd.print("The Door is Locked");
    lcd.setCursor(0,1);
    lcd.print("Enter pass to unlock");
    String pass=setPass();
    checkPass(pass);
}

void unlocked(){
lcd.clear();
isDoorLocked=false;
if(isSet()){
  lcd.setCursor(1,0);
  lcd.print("'*' to reset pass");
  lcd.setCursor(4,1);
  lcd.print("'#' to lock");
  lcd.setCursor(18,1);
  char key = keypad.getKey();
  if (key=='*') {
    lcd.clear();
    setPass();
  }else if(key=='#'){
    locked();
  }
  
}else {
  savedPass=setPass();
}
}