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

// Set the LCD address to 0x27 for a 16 chars and 2 line display
LiquidCrystal_I2C lcd(0x27, 16, 2);

// Define sensor pins
const int entrySensor = 2; // Entry sensor connected to digital pin 2
const int exitSensor  = 3; // Exit sensor connected to digital pin 3

// Variables to hold sensor states
int entryState = 0;
int exitState  = 0;

// Inventory counter
int inventoryCount = 0;

void setup() {
  // Initialize the LCD
  lcd.init();
  lcd.backlight();
  
  // Print a starting message
  lcd.setCursor(0, 0);
  lcd.print("Inventory Counter");
  lcd.setCursor(0, 1);
  lcd.print("Initializing...");

  delay(2000); // Wait for 2 seconds

  // Set sensor pins as input
  pinMode(entrySensor, INPUT);
  pinMode(exitSensor, INPUT);

  // Clear LCD
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("Current Count:");
  lcd.setCursor(0, 1);
  lcd.print(inventoryCount);
}

void loop() {
  // Read the state of the sensors
  entryState = digitalRead(entrySensor);
  exitState  = digitalRead(exitSensor);

  // If entry sensor detects object
  if (entryState == LOW) { // LOW because IR sensor gives LOW when object detected
    inventoryCount++;
    updateDisplay();
    delay(500); // Simple debounce and avoid multiple counts
  }

  // If exit sensor detects object
  if (exitState == LOW) {
    if (inventoryCount > 0) {
      inventoryCount--;
    }
    updateDisplay();
    delay(500);
  }
}

// Function to update the LCD display
void updateDisplay() {
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("Current Count:");
  lcd.setCursor(0, 1);
  lcd.print(inventoryCount);
}