#define TRIG_PIN 13
#define ECHO_PIN 12

const int ledPins[] = {2, 3, 4, 5, 6, 7, 8, 9, 10};
const int numLeds = sizeof(ledPins) / sizeof(ledPins[0]);

void setup() {
  pinMode(TRIG_PIN, OUTPUT);
  pinMode(ECHO_PIN, INPUT);
  for (int i = 0; i < numLeds; i++) {
    pinMode(ledPins[i], OUTPUT);
  }
  Serial.begin(115200);
  Serial.println("Hello");
}

float getDistance() {
  digitalWrite(TRIG_PIN, LOW);
  delayMicroseconds(2);
  digitalWrite(TRIG_PIN, HIGH);
  delayMicroseconds(10);
  digitalWrite(TRIG_PIN, LOW);
  long duration = pulseIn(ECHO_PIN, HIGH, 20000);
  if (duration == 0) return -1;
  Serial.print("distance: ");
  Serial.println(duration * 0.034/2);
  return duration * 0.034 / 2;
}

void loop() {
  float distance = getDistance();
  int ledsToLight = 0;
  
  if (distance >= 1 && distance <= 9) {
    ledsToLight = 10 - floor(distance);
  }
  Serial.print("ledsToLight:");
  Serial.println(ledsToLight);
  for (int i = 0; i < numLeds; i++) {
    digitalWrite(ledPins[i], i < ledsToLight ? HIGH : LOW);
  }
  delay(100);
}