int GREEN_LED = 13;
int RED_LED = 12;
int BUTTON = 2;
int TRIG_PIN = 14;
int ECHO_PIN = 23;
int MAX_DISTANCE = 100;


void setup() {
  Serial.begin(115200);
  Serial.println("Hello, ESP32!");
  pinMode(GREEN_LED, OUTPUT);
  pinMode(RED_LED, OUTPUT);
  pinMode(TRIG_PIN, OUTPUT);
  pinMode(ECHO_PIN, INPUT);
}

float readDistanceCM() {
  digitalWrite(TRIG_PIN, LOW);
  delayMicroseconds(2);
  digitalWrite(TRIG_PIN, HIGH);
  delayMicroseconds(10);
  digitalWrite(TRIG_PIN, LOW);
  int duration = pulseIn(ECHO_PIN, HIGH);
  return duration * 0.034 / 2;
}

void switchLed(bool busy) {
  if(busy) { 
      digitalWrite(RED_LED, HIGH);
      digitalWrite(GREEN_LED, LOW);
  } else { 
      digitalWrite(GREEN_LED, HIGH);
      digitalWrite(RED_LED, LOW);
  }
}


void loop() {
  float distance = readDistanceCM();

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

  bool isSpotBusy = distance < MAX_DISTANCE;
  switchLed(isSpotBusy);
  delay(60);
}