#include <Arduino.h>

// Pin definitions
#define TRIG_PIN 5
#define ECHO_PIN 18
#define LED1_PIN 2
#define LED2_PIN 4

// Function to get distance from the HC-SR04 sensor
long getDistance() {
  // Clear the trigPin by setting it LOW
  digitalWrite(TRIG_PIN, LOW);
  delayMicroseconds(2);

  // Trigger the sensor by setting the trigPin HIGH for 10 microseconds
  digitalWrite(TRIG_PIN, HIGH);
  delayMicroseconds(10);
  digitalWrite(TRIG_PIN, LOW);

  // Read the echoPin, and return the sound wave travel time in microseconds
  long duration = pulseIn(ECHO_PIN, HIGH);

  // Calculate the distance (in cm) based on the speed of sound (340 m/s)
  long distance = duration * 0.034 / 2;

  return distance;
}

void setup() {
  // Initialize serial communication at 115200 bits per second
  Serial.begin(115200);

  // Configure pin modes
  pinMode(TRIG_PIN, OUTPUT);
  pinMode(ECHO_PIN, INPUT);
  pinMode(LED1_PIN, OUTPUT);
  pinMode(LED2_PIN, OUTPUT);
}

void loop() {
  // Get the distance from the HC-SR04 sensor
  long distance = getDistance();
  Serial.print("Distance: ");
  Serial.print(distance);
  Serial.println(" cm");

  // Define distance thresholds for flood warning
  const long SAFE_DISTANCE = 100; // Safe distance in cm
  const long WARNING_DISTANCE = 50; // Warning distance in cm

  // Control LEDs based on distance
  if (distance > SAFE_DISTANCE) {
    // Safe distance
    digitalWrite(LED1_PIN, LOW); // Green LED off
    digitalWrite(LED2_PIN, LOW); // Red LED off
  } else if (distance > WARNING_DISTANCE && distance <= SAFE_DISTANCE) {
    // Warning distance
    digitalWrite(LED1_PIN, HIGH); // Green LED on
    digitalWrite(LED2_PIN, LOW); // Red LED off
  } else {
    // Flood distance
    digitalWrite(LED1_PIN, LOW); // Green LED off
    digitalWrite(LED2_PIN, HIGH); // Red LED on
  }

  // Wait for 500 milliseconds before the next loop
  delay(500);
}