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

// Define pins for LEDs
const int redLED = 2;
const int blueLED = 3;
const int yellowLED = 4;
const int greenLED = 5;

// Variable for distance measurement
long duration;
int distance;

// Container depth in cm (adjusted to 400 cm)
const int containerDepth = 400;  // Maximum depth of the container in cm

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

  // Set pin modes
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);
  pinMode(redLED, OUTPUT);
  pinMode(blueLED, OUTPUT);
  pinMode(yellowLED, OUTPUT);
  pinMode(greenLED, OUTPUT);
}

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

  // Read echo response
  duration = pulseIn(echoPin, HIGH);

  // Calculate distance
  distance = duration * 0.034 / 2;

  // Calculate percentage
  int percentage = map(distance, containerDepth, 0, 0, 100);

  // Clamp percentage to 0-100 range
  if (percentage < 0) percentage = 0;
  if (percentage > 100) percentage = 100;

  // Display percentage in Serial Monitor
  Serial.print("Distance: ");
  Serial.print(distance);
  Serial.print(" cm, Percentage: ");
  Serial.print(percentage);
  Serial.println("%");

  // Control LEDs based on percentage
  if (percentage <= 25) {
    setLEDs(HIGH, LOW, LOW, LOW);  // Red LED
  } else if (percentage <= 50) {
    setLEDs(LOW, HIGH, LOW, LOW);  // Blue LED
  } else if (percentage <= 75) {
    setLEDs(LOW, LOW, HIGH, LOW);  // Yellow LED
  } else {
    setLEDs(LOW, LOW, LOW, HIGH);  // Green LED
  }

  // Delay for stability
  delay(500);
}

// Function to control LEDs
void setLEDs(int red, int blue, int yellow, int green) {
  digitalWrite(redLED, red);
  digitalWrite(blueLED, blue);
  digitalWrite(yellowLED, yellow);
  digitalWrite(greenLED, green);
}