#define TRIG_PIN 5
#define ECHO_PIN 18

#define GREEN_LED 12
#define RED_LED 14

long duration;
float distance;

void setup() {
  Serial.begin(115200);

  pinMode(TRIG_PIN, OUTPUT);
  pinMode(ECHO_PIN, INPUT);

  pinMode(GREEN_LED, OUTPUT);
  pinMode(RED_LED, OUTPUT);
}

void loop() {
  // Clear TRIG
  digitalWrite(TRIG_PIN, LOW);
  delayMicroseconds(2);

  // Send 10us pulse
  digitalWrite(TRIG_PIN, HIGH);
  delayMicroseconds(10);
  digitalWrite(TRIG_PIN, LOW);

  // Measure pulse duration
  duration = pulseIn(ECHO_PIN, HIGH);

  // Calculate distance (cm)
  distance = duration * 0.034 / 2;

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

  if (distance < 10) {
    // Car detected
    digitalWrite(RED_LED, HIGH);
    digitalWrite(GREEN_LED, LOW);
    Serial.println("Parking Slot: OCCUPIED");
  } else {
    // Slot empty
    digitalWrite(RED_LED, LOW);
    digitalWrite(GREEN_LED, HIGH);
    Serial.println("Parking Slot: AVAILABLE");
  }

  Serial.println("------------------------");
  delay(1000);
}