Door Security System

/*
    Hello, welcome to my code world, my project today is the door security system project.
    I am writing the codes on the project myself,
    I may have deficiencies, you can correct me and improve me,
    thank you in advance.

    My nickname is gncmuh and my name is Sabri GENC

    Good work on your code world :)

*/

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

Servo servo;
const byte servo_pin PROGMEM=3;
const byte rows PROGMEM=4;
const byte cols PROGMEM=4;

struct pins {
  const byte pinler[1]={2};
  byte row_pins[rows]={11,10,9,8}; 
  byte col_pins[cols]={7,6,5,4};
};
struct pins pin;
char key_board[rows][cols]={
  {'1','2','3','A'},          //A this character left direction  and  B this character right direction
  {'4','5','6','B'},
  {'7','8','9','C'},
  {'*','0','#','D'}
};
LiquidCrystal_I2C lcd(0x27,16,2);
Keypad key=Keypad(makeKeymap(key_board),pin.row_pins,pin.col_pins,rows,cols);
char memory[4];
char direction_characters[4]={'<','>','N','Y'}; 
bool flag=false;
char incoming_key;
unsigned long timer=0;
byte counter=7; 
byte memory_counter=0;
char password[]="1998";  //  <-- In this project in real password
bool out_password=false;
void setup()
{
  Serial.begin(9600);
  Wire.begin(); 
  servo.attach(servo_pin);servo.write(0);
  screen_start();
}

void loop()
{
  screen_management();
  delay(1);
 
  
}
void screen_start() {
  if(!bool(0))
  {
    lcd.init();lcd.backlight();lcd.setCursor(1,0);
    lcd.print(F("GNCMUH PROTECH"));
    lcd.setCursor(4,1);
    for(int i=1; i<=8; i++) 
    {
      lcd.print(F("*"));delay(80); 
    }
    delay(1000);lcd.clear();
  }
}
void screen_management() {
  
  if(!bool(0))
  {
    if(flag==false)
    {
      first_page();
      flag=!flag;
    }
    if(flag==true)
    {
      here2:
      if(millis()-timer>2500)
      {
        timer=millis();
        lcd.setCursor(counter,1);lcd.blink();
      }
      incoming_key=key.getKey();
      lcd.setCursor(counter,1);
      if(incoming_key=='A' or incoming_key=='B' or incoming_key=='C' or incoming_key=='D')
      {
        if(incoming_key=='A') 
        {
          counter--;
          if(counter<6) counter=7;           
        }
        if(incoming_key=='B')
        {
          counter++;
          if(counter>8) counter=7;
        }       
        if(incoming_key=='D' and counter==8)
        {
          here:
          counter=7;
          lcd.clear();
          lcd.setCursor(0,1);lcd.print(direction_characters[0]);
          lcd.setCursor(6,1);lcd.print(direction_characters[2]);
          lcd.setCursor(8,1);lcd.print(direction_characters[3]);
          lcd.setCursor(15,1);lcd.print(direction_characters[1]);
          lcd.setCursor(1,0);
          lcd.print(F("ENTER PASSOWORD"));
          do
          { 
            incoming_key=key.getKey();
            lcd.setCursor(counter,1);
            if(incoming_key=='A')
            {
              counter--;
              if(counter<6) counter-=5;
              else if(counter==14) counter=7;
            }
            if(incoming_key=='B')
            {
              counter++;
              if(counter>8) counter+=6;
              else if(counter==1) counter=7;
            }
            if(incoming_key=='D' and counter==8)
            {
              second_page();
              if(atoi(memory)==atoi(password))
              {
                lcd.clear();lcd.print(F("CORRECT PASSWORD"));
                delay(500);lcd.clear();
                lcd.print(F("DOOR OPEN"));
                servo.write(90);
                delay(3000);
                lcd.clear();lcd.print(F("LOCKED"));
                delay(1000);
                first_page();
                goto here2;
              }
              else
              {
                lcd.clear();lcd.print(F("WRONG PASSWORD"));
                delay(1000);
                first_page();
                goto here2;
              }
            }
            if(incoming_key=='D' and counter==6)
            {
              first_page();
              break;
            }
            if(incoming_key=='D' and counter==15)
            {
              counter=7;
              lcd.clear();lcd.setCursor(1,0);
              lcd.print(F("CHANGE PASSWORD"));
              lcd.setCursor(0,1);lcd.print(direction_characters[0]);
              lcd.setCursor(6,1);
              for(int i=2; i<=3; i++)
              {
                lcd.print(direction_characters[i]);lcd.print(F(" "));
              }
              if(!bool(0))
              {
                while(true)
                {
                  incoming_key=key.getKey();
                  if(incoming_key=='A')
                  {
                    counter--;
                    if(counter<6) counter=0;
                  }
                  if(incoming_key=='B')
                  {
                    counter++;
                    if(counter>8) counter=7;
                    else if(counter==1) counter=7;
                  }
                  if(incoming_key=='D' and counter==0)
                  {
                     counter=7;
                     goto here;
                  }
                  if(incoming_key=='D' and counter==6)
                  {
                    counter=7;
                    goto here;
                  }
                  if(incoming_key=='D' and counter==8)
                  {
                    third_page();
                    delay(2000);
                    counter=7;
                    first_page();
                    goto here2;
                  }
                  lcd.setCursor(counter,1);
                  delay(1);
                }
                
              }
            }
            if(incoming_key=='D' and counter==0)
            {
              counter=7;
              first_page();
              break;
            }
            delay(5);
            
          }while(!bool(0));
        }
      }
    }
  }
}
void first_page() {
  servo.write(0);lcd.clear();
  lcd.setCursor(3,0);
  lcd.print(F("HOME PAGE"));lcd.setCursor(6,1);
  for(int i=0; i<4; i++) 
  {
    if(i!=2 and i!=3)
    {
      lcd.print(direction_characters[i]);lcd.print(F(" "));
    }
    delay(1);
  }
  lcd.blink();
}

void second_page() {
  lcd.clear();lcd.noBlink();
  lcd.setCursor(1,0);
  lcd.print(F("ENTER PASSWORD"));
  memory_counter=0;
  if(!bool(0))
  {
    while(memory_counter<4)
    {
      char incoming_character=key.getKey();
      if(incoming_character)
      {
        lcd.setCursor(memory_counter+5,1);
        lcd.print(F("*"));
        memory[memory_counter]=incoming_character;
        memory_counter++;
      }
      delay(1);
    }
    memory_counter=0;
    counter=7;
    delay(300);
  }
}
void third_page() {
  memory_counter=0;
  lcd.clear();lcd.noBlink();
  lcd.print(F("CURRENT PASSWORD"));
  while(memory_counter<4)
  {
      char incoming_character=key.getKey();
      if(incoming_character)
      {
        lcd.setCursor(memory_counter+5,1);
        lcd.print(F("*"));
        memory[memory_counter]=incoming_character;
        memory_counter++;
      }
      delay(1);
  }
  delay(300);
  if(atoi(password)==atoi(memory))
  {
    memory_counter=0;
    lcd.clear();lcd.setCursor(1,0);lcd.print(F("CORRECT PASSWORD"));
    delay(1000);
    lcd.clear();lcd.print(F("NEW PASSWORD"));
    while(memory_counter<4)
    {
      char incoming_character=key.getKey();
      if(incoming_character)
      {
        lcd.setCursor(memory_counter+5,1);
        lcd.print(F("*"));
        memory[memory_counter]=incoming_character;
        memory_counter++;
      }
      delay(1);
    }
    for(int i=0; i<4; i++)
    {
      password[i]=memory[i];
    }
    delay(300);
    memory_counter=0;
    delay(500);
    lcd.clear();lcd.setCursor(0,0);
    lcd.print(F("PASSWORD CHANGED"));counter=7;
  }
  else
  {
    lcd.clear();lcd.print(F("PASSWORD INCORRECT"));
    delay(1000);
    counter=7;
    first_page();
  }
}