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

#define OLED_RESET 4
Adafruit_SSD1306 display(OLED_RESET);

const int ledPin = 16; // LED pin
const int potPin = 34; // Potentiometer
const int pirPin = 14; // PIR
const int trigPin = 5; // trigger pin
const int echoPin = 4; // echo pin

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

  pinMode(ledPin, OUTPUT);
  pinMode(pirPin, INPUT);
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);

  // Initialize OLED display
  if(!display.begin(SSD1306_SWITCHCAPVCC, 0x3C)) {
    Serial.println(F("SSD1306 allocation failed"));
    for(;;);
  }
  delay(1000);
  display.clearDisplay();
  display.setTextColor(WHITE);
  display.setTextSize(1);
  display.setCursor(0,0);
  display.println("Smart Classroom");
  display.display();
  delay(2000);
}
void loop() {
  int presentCount=70;
  int absentCount=4;
  // Read potentiometer value
  int potValue = analogRead(potPin);
  // Read PIR sensor state
  int pirState = digitalRead(pirPin);
  // Read ultrasonic sensor distance
  int distance = readUltrasonicDistance();

  // Display sensor data on OLED
 display.clearDisplay();
  display.setTextSize(1);
  display.setTextColor(SSD1306_WHITE);
  display.setCursor(0, 0);
  display.print("Present: ");
  display.println(presentCount);
  display.print("Absent: ");
  display.println(absentCount);
  display.display();

  // Turn LED on if PIR sensor detects motion
  if (pirState == HIGH) {
    digitalWrite(ledPin, HIGH);
  } else {
    digitalWrite(ledPin, LOW);
  }

  delay(500); // delay for stability
}

int readUltrasonicDistance() {
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);
long duration = pulseIn(echoPin, HIGH);
  int distance = duration * 0.034 / 2;
  return distance;
}