#include <LiquidCrystal_I2C.h>
LiquidCrystal_I2C lcd(0x27,16,2);

int push1 = 2;
int push2 = 3;
int push3 = 4;
int push4 = 5;
int led = 13;
String a, b , c, d, e ;
int sp = 0 , sp1 = 0 ;

void setup()
 {
  pinMode(push1 , INPUT);
  pinMode(push2, INPUT);
  pinMode(push3, INPUT);
  pinMode(push4, INPUT);
  pinMode(led, OUTPUT);
  Serial.begin(9600);
  lcd.init();
  lcd.backlight();
  lcd.setCursor(0,0);
  lcd.print("New password:");
  lcd.setCursor(0,1);

  // put your setup code here, to run once:

}

void loop()
 {
  int sw1 = digitalRead(push1);
  int sw2 = digitalRead(push2);
  int sw3 = digitalRead(push3);
  int sw4 = digitalRead(push4);

  if (sp == 0)
  {
  
  if(sw1 == 1)
  {
    b+="1";
    delay(1000);
    lcd.print("*");
  }
  if(sw2 == 1)
  {
    b+="2";
    delay(1000);
    lcd.print("*");
  }
  if(sw3 == 1)
  {
    b+="3";
    delay(1000);
    lcd.print("*");
  }
  if(b.length()>=4)
  {
    lcd.setCursor(0,0);
    lcd.print("password saved");
    lcd.setCursor(0,1);
    lcd.print("         ");
    delay(2000);
    lcd.setCursor(0,0);
    lcd.print("Enter password");
    lcd.setCursor(0,1);
    sp = 1;

  }
  }
  else if(sp == 1)
  {
    if(sw1 == 1)
    {
      a+="1";
      delay(1000);
      lcd.print("*");
    }
    if(sw2 == 1)
    {
      a+="2";
      delay(1000);
      lcd.print("*");
    }
    if(sw3 == 1);
    {
      a+="3";
      delay(1000);
      lcd.print("*");
    }
    if(a.length()>=4)
    {
      if(a == b)
      {
        lcd.setCursor(0,0);
        lcd.print("password verified");
        lcd.setCursor(0,1);
        lcd.print("          ");
        delay(2000);
        lcd.setCursor(0,0);
        lcd.print("Enter password");
        lcd.setCursor(0,1);
        a = "";
        digitalWrite(led, 1);
        delay(1000);
        digitalWrite(led, 0);
        c = b;

      }
    
     else if(a != b)
      {
        lcd.setCursor(0,0);
        lcd.print("wrong password");
        lcd.setCursor(0,1);
        lcd.print("         ");
        delay(2000);
        lcd.setCursor(0,0);
        lcd.print("Enter password");
        lcd.setCursor(0,1);
        a = "";


      }
    }
    
  }
  if (sw4 == 1)
  {
    lcd.setCursor(0,0);
    lcd.print("change password");
    lcd.setCursor(0,1);
    lcd.print("        ");
    delay(2000);
    lcd.setCursor(0,0);
    lcd.print("Enter old password");
    lcd.print(0,1);
    delay(2000);
    sp = 2;

  }
   else if (sp == 2)
  {
   if(sw1 == 1)
   {
     d+="1";
     delay(1000);
     lcd.print("*");
   }
   if(sw2 == 1 )
   {
     d += "2";
     delay(1000);
     lcd.print("*");
   }
   if(sw3 == 1);
   {
     d+="3";
     delay(1000);
     lcd.print("*");
   }
   if(d.length()>=4)
     {
       if(d == c)
       {
         lcd.setCursor(0,0);
         lcd.print("old password verified");
         lcd.setCursor(0,1);
         lcd.print("        ");
         delay(2000);
         lcd.setCursor(0,0);
         lcd.print("Enter new password");
         lcd.setCursor(0,1);
         sp = 3;
         d = "";
         sp1 = 1;        
       }
       else
       {
         lcd.setCursor(0,0);
         lcd.print('wrong password');
       }
     }
  }
  else if(sp1 == 1)
  {
     if(sw1 == 1)
   {
     e +="1";
     delay(1000);
     lcd.print("*");
   }
   if(sw2 == 1 )
   {
     e += "2";
     delay(1000);
     lcd.print("*");
   }
   if(sw3 == 1);
   {
     e +="3";
     delay(1000);
     lcd.print("*");
   }
   if(e.length()>=4)
   {
     lcd.setCursor(0,0);
     lcd.print("password saved");
     lcd.setCursor(0,1);
     lcd.print("          ");
     delay(2000);
     lcd.setCursor(0,0);
     lcd.print('Enter password');
     lcd.setCursor(0,1);
     b = e;
     e = "";
     sp = 1;
     sp1 = 0;
   }
  }
  // put your main code here, to run repeatedly:

}