#define TRIG 5
#define ECHO 18

#define LED_LOW 19
#define LED_MED 21
#define LED_HIGH 22
#define LED_FULL 23

long duration;
int distance;

void setup() {
  pinMode(TRIG, OUTPUT);
  pinMode(ECHO, INPUT);

  pinMode(LED_LOW, OUTPUT);
  pinMode(LED_MED, OUTPUT);
  pinMode(LED_HIGH, OUTPUT);
  pinMode(LED_FULL, OUTPUT);

  Serial.begin(115200);
}

void loop() {
  // Trigger ultrasonic pulse
  digitalWrite(TRIG, LOW);
  delayMicroseconds(2);
  digitalWrite(TRIG, HIGH);
  delayMicroseconds(10);
  digitalWrite(TRIG, LOW);

  duration = pulseIn(ECHO, HIGH);
  distance = duration * 0.034 / 2; // convert to cm

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

  // Reset LEDs
  digitalWrite(LED_LOW, LOW);
  digitalWrite(LED_MED, LOW);
  digitalWrite(LED_HIGH, LOW);
  digitalWrite(LED_FULL, LOW);

  // Tank height assumption = 30 cm
  if (distance > 20) {
    Serial.println("Water Level: LOW");
    digitalWrite(LED_LOW, HIGH);
  } else if (distance > 10 && distance <= 20) {
    Serial.println("Water Level: MEDIUM");
    digitalWrite(LED_MED, HIGH);
  } else if (distance > 5 && distance <= 10) {
    Serial.println("Water Level: HIGH");
    digitalWrite(LED_HIGH, HIGH);
  } else if (distance <= 5) {
    Serial.println("Water Level: FULL");
    digitalWrite(LED_FULL, HIGH);
  }

  delay(1000);
}