#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>

#define SCREEN_WIDTH 128
#define SCREEN_HEIGHT 64
#define OLED_RESET -1
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);

// Ultrasonic sensor pins
#define TRIG_PIN 3
#define ECHO_PIN 4

int count = 0;
long duration;
int distance;
bool objectDetected = false; // To avoid multiple counts for the same object

void setup() {
  // Initialize serial monitor
  Serial.begin(9600);

  // Pin modes
  pinMode(TRIG_PIN, OUTPUT);
  pinMode(ECHO_PIN, INPUT);

  // OLED initialization
  if (!display.begin(SSD1306_SWITCHCAPVCC, 0x3C)) {
    Serial.println(F("SSD1306 allocation failed"));
    for (;;);
  }

  display.clearDisplay();
  display.setTextSize(1); // Smaller text to fit OLED
  display.setTextColor(SSD1306_WHITE);
  display.setCursor(0, 10);
  display.println("Head Counter");
  display.display();
  delay(2000);
}

void loop() {
  // Send 10us pulse to trigger pin
  digitalWrite(TRIG_PIN, LOW);
  delayMicroseconds(2);
  digitalWrite(TRIG_PIN, HIGH);
  delayMicroseconds(10);
  digitalWrite(TRIG_PIN, LOW);

  // Read echo pin
  duration = pulseIn(ECHO_PIN, HIGH);
  distance = duration * 0.034 / 2; // Convert to cm

  Serial.print("Distance: ");
  Serial.println(distance);

  // If object is within 15 cm and was not previously detected
  if (distance < 50 && !objectDetected) {
    count++;
    objectDetected = true;

    // Update OLED
    display.clearDisplay();
    display.setTextSize(1);
    display.setCursor(0, 20);
    display.print("Count: ");
    display.println(count);
    display.display();
    delay(500);
  }

  // Reset detection when object moves away
  if (distance > 20) {
    objectDetected = false;
  }

  delay(100);
}