#include <Servo.h> // Includes the servo library
#include <Wire.h>
#include <LiquidCrystal_I2C.h>

// Define LCD and servo objects
LiquidCrystal_I2C lcd(0x27, 20, 4);
Servo myservo;

// Define IR sensor pins
#define ir_enter 2
#define ir_back  4
#define ir_car1 5
#define ir_car2 6
#define ir_car3 7

// Define slot states and flags
int S[3] = {0, 0, 0};
int flag1 = 0, flag2 = 0;
int slot = 3;

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

    // Initialize IR sensor pins
    for (int i = 0; i < 3; i++) {
        pinMode(ir_car1 + i, INPUT);
    }
    pinMode(ir_enter, INPUT);
    pinMode(ir_back, INPUT);

    // Initialize servo and LCD
    myservo.attach(3);
    myservo.write(90);
    lcd.begin(20, 4);
    lcd.setCursor(0, 1);
    lcd.print("    Car parking  ");
    lcd.setCursor(0, 2);
    lcd.print("      System     ");
    delay(2000);
    lcd.clear();

    // Read initial sensor states and calculate available slots
    Read_Sensor();
    slot = slot - (S[0] + S[1] + S[2]);
}

void loop() {
    Read_Sensor();
    
    lcd.setCursor(0, 0);
    lcd.print("   Have Slot: ");
    lcd.print(slot);
    lcd.print("    ");
    
    // Display sensor states
    for (int i = 0; i < 3; i++) {
        lcd.setCursor((i % 2) * 10, 1 + (i / 2));
        lcd.print("S");
        lcd.print(i + 1);
        lcd.print(":");
        if (S[i] == 1) {
            lcd.print("Fill ");
        } else {
            lcd.print("Empty");
        }
    }

    // Handle entering cars
    if (digitalRead(ir_enter) == LOW && flag1 == 0) {
        if (slot > 0) {
            flag1 = 1;
            if (flag2 == 0) {
                myservo.write(180);
                slot--;
            }
        } else {
            lcd.setCursor(0, 0);
            lcd.print(" Sorry Parking Full ");
            delay(1500);
        }
    }

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

    // Reset flags and servo position
    if (flag1 == 1 && flag2 == 1) {
        delay(1000);
        myservo.write(90);
        flag1 = 0;
        flag2 = 0;
    }

    delay(1);
}

void Read_Sensor() {
    // Reset sensor states
    for (int i = 0; i < 3; i++) {
        S[i] = (digitalRead(ir_car1 + i) == LOW) ? 1 : 0;
    }
}