#define TRIG 5
#define ECHO 18
#define BUZZER 2

float tankHeight = 100.0;

long duration;
float distance;
float waterLevel;

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

  pinMode(TRIG, OUTPUT);
  pinMode(ECHO, INPUT);
  pinMode(BUZZER, OUTPUT);

  Serial.println("Flood Monitoring System Started...");
}

float getDistance() {
  digitalWrite(TRIG, LOW);
  delayMicroseconds(2);

  digitalWrite(TRIG, HIGH);
  delayMicroseconds(10);
  digitalWrite(TRIG, LOW);

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

  return distance;
}

void loop() {

  distance = getDistance();
  waterLevel = tankHeight - distance;

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

  Serial.print("Water Level: ");
  Serial.print(waterLevel);
  Serial.println(" cm");

  if (waterLevel > 80) {
    Serial.println("FLOOD ALERT!");
    digitalWrite(BUZZER, HIGH);
    delay(200);
    digitalWrite(BUZZER, LOW);
    delay(200);

  } else if (waterLevel > 50) {
    Serial.println("Warning Level");
    digitalWrite(BUZZER, HIGH);
    delay(500);
    digitalWrite(BUZZER, LOW);
    delay(500);

  } else {
    Serial.println("Safe Level");
    digitalWrite(BUZZER, LOW);
    delay(1000);
  }
}