#define TRIG_PIN 5
#define ECHO_PIN 18

#define LED_LOW 21
#define LED_MEDIUM 22
#define LED_HIGH 23
#define BUZZER 19

long duration;
float distance;

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

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

  pinMode(LED_LOW, OUTPUT);
  pinMode(LED_MEDIUM, OUTPUT);
  pinMode(LED_HIGH, OUTPUT);
  pinMode(BUZZER, OUTPUT);
}

void loop() {

  // Send ultrasonic pulse
  digitalWrite(TRIG_PIN, LOW);
  delayMicroseconds(2);
  digitalWrite(TRIG_PIN, HIGH);
  delayMicroseconds(10);
  digitalWrite(TRIG_PIN, LOW);

  duration = pulseIn(ECHO_PIN, HIGH);
  distance = duration * 0.034 / 2;

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

  // Tank height example: 30 cm
  if (distance > 20) {
    // LOW water
    digitalWrite(LED_LOW, HIGH);
    digitalWrite(LED_MEDIUM, LOW);
    digitalWrite(LED_HIGH, LOW);
    digitalWrite(BUZZER, LOW);
  }
  else if (distance > 10 && distance <= 20) {
    // MEDIUM water
    digitalWrite(LED_LOW, LOW);
    digitalWrite(LED_MEDIUM, HIGH);
    digitalWrite(LED_HIGH, LOW);
    digitalWrite(BUZZER, LOW);
  }
  else {
    // HIGH water (Tank Full)
    digitalWrite(LED_LOW, LOW);
    digitalWrite(LED_MEDIUM, LOW);
    digitalWrite(LED_HIGH, HIGH);
    digitalWrite(BUZZER, HIGH);  // Alert when full
  }

  delay(1000);
}