// Define pins for ultrasonic sensor
const int trigPin = 9;
const int echoPin = 10;

// Define LED pins
const int led1 = 2;
const int led2 = 3;
const int led3 = 4;
const int led4 = 5;
const int led5 = 6;

// Variable to store the distance
long distance;

void setup() {
  // Initialize the serial communication
  Serial.begin(9600);

  // Set ultrasonic pins
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);

  // Set LED pins as output
  pinMode(led1, OUTPUT);
  pinMode(led2, OUTPUT);
  pinMode(led3, OUTPUT);
  pinMode(led4, OUTPUT);
  pinMode(led5, OUTPUT);
}

void loop() {
  // Get the distance measured by the ultrasonic sensor
  distance = getDistance();

  // Determine which LEDs to light up based on distance
  if (distance >= 100 && distance <= 124) {
    turnOnLEDs(5); // All 5 LEDs on
  } else if (distance >= 125 && distance <= 149) {
    turnOnLEDs(4); // 4 LEDs on
  } else if (distance >= 150 && distance <= 174) {
    turnOnLEDs(3); // 3 LEDs on
  } else if (distance >= 175 && distance <= 199) {
    turnOnLEDs(2); // 2 LEDs on
  } else if (distance >= 200 && distance <= 254) {
    turnOnLEDs(1); // 1 LED on
  } else if (distance == 255) {
    turnOnLEDs(0); // No LEDs on
  } else {
    turnOnLEDs(0); // No LEDs on for 0-99 cm
  }

  // Print distance for debugging
  Serial.print("Distance: ");
  Serial.println(distance);

  // Small delay to stabilize readings
  delay(100);
}

// Function to measure distance
long getDistance() {
  // Clear the trigPin
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);

  // Set the trigPin on HIGH state for 10 microseconds
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);

  // Read the echoPin and calculate distance
  long duration = pulseIn(echoPin, HIGH);
  long distance = duration * 0.034 / 2; // Distance in cm
  return distance;
}

// Function to control the LEDs
void turnOnLEDs(int numLEDs) {
  // Turn off all LEDs initially
  digitalWrite(led1, LOW);
  digitalWrite(led2, LOW);
  digitalWrite(led3, LOW);
  digitalWrite(led4, LOW);
  digitalWrite(led5, LOW);

  // Turn on the required number of LEDs
  if (numLEDs >= 1) digitalWrite(led1, HIGH);
  if (numLEDs >= 2) digitalWrite(led2, HIGH);
  if (numLEDs >= 3) digitalWrite(led3, HIGH);
  if (numLEDs >= 4) digitalWrite(led4, HIGH);
  if (numLEDs >= 5) digitalWrite(led5, HIGH);
}