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

const int trigPin1 = 2;
const int echoPin1 = 3;
const int trigPin2 = 4;
const int echoPin2 = 5;
const int entryLedPin = 6;
const int exitLedPin = 7;

LiquidCrystal_I2C lcd(0x27, 16, 2);

long duration1, duration2;
int distance1, distance2;
int peopleIn = 0;
int peopleOut = 0;

void init() {
  pinMode(trigPin1, OUTPUT);
  pinMode(echoPin1, INPUT);
  pinMode(trigPin2, OUTPUT);
  pinMode(echoPin2, INPUT);
  pinMode(entryLedPin, OUTPUT);
  pinMode(exitLedPin, OUTPUT);

  lcd.begin();
  lcd.backlight();
  lcd.setCursor(0, 0);
  lcd.print("In: 0  Out: 0");
}

void loop() {
  // Measure distance with sensor 1
  digitalWrite(trigPin1, LOW);
  delayMicroseconds(2);
  digitalWrite(trigPin1, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin1, LOW);
  duration1 = pulseIn(echoPin1, HIGH);
  distance1 = duration1 * 0.034 / 2;

  // Measure distance with sensor 2
  digitalWrite(trigPin2, LOW);
  delayMicroseconds(2);
  digitalWrite(trigPin2, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin2, LOW);
  duration2 = pulseIn(echoPin2, HIGH);
  distance2 = duration2 * 0.034 / 2;

  // Threshold distance for detecting entry/exit (e.g., 50 cm)
  int threshold = 50;

  // Detect if someone enters (sensor 1 triggered before sensor 2)
  if (distance1 < threshold && distance2 >= threshold) {
    delay(500); // delay to debounce and confirm
    if (distance1 < threshold && distance2 >= threshold) { // double check
      peopleIn++;
      digitalWrite(entryLedPin, HIGH); // turn on green LED
      delay(200); // LED on duration
      digitalWrite(entryLedPin, LOW); // turn off green LED
      lcd.setCursor(0, 0);
      lcd.print("In: ");
      lcd.print(peopleIn);
      lcd.print("  Out: ");
      lcd.print(peopleOut);
    }
  }

  // Detect if someone exits (sensor 2 triggered before sensor 1)
  if (distance2 < threshold && distance1 >= threshold) {
    delay(500); // delay to debounce and confirm
    if (distance2 < threshold && distance1 >= threshold) { // double check
      peopleOut++;
      digitalWrite(exitLedPin, HIGH); // turn on red LED
      delay(200); // LED on duration
      digitalWrite(exitLedPin, LOW); // turn off red LED
      lcd.setCursor(0, 0);
      lcd.print("In: ");
      lcd.print(peopleIn);
      lcd.print("  Out: ");
      lcd.print(peopleOut);
    }
  }

  delay(100);
}

}