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

LiquidCrystal_I2C lcd(0x27, 16, 2); // Initialize 16x2 LCD I2C display
Servo myservo;

#define ir_enter 2
#define ir_back  4

#define ir_car1 5
#define ir_car2 6
#define ir_car3 7
#define ir_car4 8


#define green_led1 A0
#define red_led1 A1
#define green_led2 A2
#define red_led2 A3
#define green_led3 11
#define red_led3 12
#define green_led4 9
#define red_led4 10


int S1=0, S2=0, S3=0, S4=0;
int flag1=0, flag2=0; 
int slot = 4;  

void setup(){
  Serial.begin(9600);

  pinMode(ir_car1, INPUT);
  pinMode(ir_car2, INPUT);
  pinMode(ir_car3, INPUT);
  pinMode(ir_car4, INPUT);

  
  pinMode(green_led1, OUTPUT);
  pinMode(red_led1, OUTPUT);
  pinMode(green_led2, OUTPUT);
  pinMode(red_led2, OUTPUT);
  pinMode(green_led3, OUTPUT);
  pinMode(red_led3, OUTPUT);
  pinMode(green_led4, OUTPUT);
  pinMode(red_led4, OUTPUT);
 

  pinMode(ir_enter, INPUT);
  pinMode(ir_back, INPUT);
  
  myservo.attach(3);
  myservo.write(90);

  lcd.init(); // Initialize the LCD
  lcd.backlight(); // Turn on the backlight
  lcd.setCursor(0, 0);
  lcd.print("Available Slots: ");
  lcd.setCursor(0, 1);
  lcd.print(slot); // Display initial available slots
  delay(2000);

  Read_Sensor();

  int total = S1+S2+S3+S4;
  slot = slot - total;
}

void loop(){
  Read_Sensor();

  lcd.setCursor(0, 1);
  lcd.print(slot); // Update available slots on LCD
  
  if(digitalRead(ir_enter) == 0 && flag1==0){
    if(slot>0){
      flag1=1;
      if(flag2==0){
        myservo.write(180);
        slot = slot-1;
      }
    }else{
      lcd.setCursor(0, 0);
      lcd.print("Sorry Parking Full");
      delay(1500);
    }
  }

  if(digitalRead(ir_back) == 0 && flag2==0){
    flag2=1;
    if(flag1==0){
      myservo.write(180);
      slot = slot+1;
    }
  }

  if(flag1==1 && flag2==1){
    delay(1000);
    myservo.write(90);
    flag1=0, flag2=0;
  }

  updateLEDs();

  delay(1);
}

void Read_Sensor(){
  S1=0, S2=0, S3=0, S4=0;

  if(digitalRead(ir_car1) == 0){S1=1;}
  if(digitalRead(ir_car2) == 0){S2=1;}
  if(digitalRead(ir_car3) == 0){S3=1;}
  if(digitalRead(ir_car4) == 0){S4=1;}
 
} 

void updateLEDs(){
  digitalWrite(green_led1, !S1);
  digitalWrite(red_led1, S1);
  digitalWrite(green_led2, !S2);
  digitalWrite(red_led2, S2);
  digitalWrite(green_led3, !S3);
  digitalWrite(red_led3, S3);
  digitalWrite(green_led4, !S4);
  digitalWrite(red_led4, S4);
 
}