#include <Servo.h> // Include the Servo library

Servo myServo; // Create a Servo object

// Define HC-SR04 pins
const int trigPin = 11; // Trigger pin connected to Arduino pin 11
const int echoPin = 12; // Echo pin connected to Arduino pin 12

// Define fairy lights pin
const int lightsPin = 3; // Connected to the PWM control pin of fairy lights

// Define the threshold distance (in cm)
const int distanceThreshold = 10;

// Fade settings
const int fadeDelay = 5; // Delay between brightness adjustments (in milliseconds)

void setup() {
  // Initialize the servo
  myServo.attach(9); // Attach the servo to pin 9
  myServo.write(0);  // Set the servo to 0 degrees initially

  // Initialize the HC-SR04 pins
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);

  // Initialize fairy lights pin
  pinMode(lightsPin, OUTPUT);
  analogWrite(lightsPin, 0); // Start with lights off

  // Begin Serial communication for debugging (optional)
  Serial.begin(9600);
}

void loop() {
  int distance = measureDistance(); // Measure the distance
  
  // Print the distance to Serial Monitor (optional)
  Serial.print("Distance: ");
  Serial.print(distance);
  Serial.println(" cm");

  if (distance > 0 && distance <= distanceThreshold) {
    // Gradually fade in the lights and start the servo movement
    fadeLights(true);
    delay(500); // Short delay to sync the fade-in with the servo movement

    // Move the servo to 90 degrees and hold for 5 seconds
    myServo.write(90);
    delay(5000);

    // Return the servo to 0 degrees
    myServo.write(0);

    // Gradually fade out the lights
    fadeLights(false);
  }

  delay(100); // Small delay for stability
}

// Function to measure distance using HC-SR04
int measureDistance() {
  // Send a 10 microsecond HIGH pulse to the trigger pin
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);

  // Measure the echo time (duration of the HIGH signal in microseconds)
  long duration = pulseIn(echoPin, HIGH);

  // Calculate the distance in cm (duration / 58 = distance in cm)
  int distance = duration / 58;

  // Return the distance
  return distance;
}

// Function to gradually fade in or fade out the lights
void fadeLights(bool fadeIn) {
  if (fadeIn) {
    // Gradually increase brightness
    for (int brightness = 0; brightness <= 255; brightness++) {
      analogWrite(lightsPin, brightness);
      delay(fadeDelay); // Adjust fade speed
    }
  } else {
    // Gradually decrease brightness
    for (int brightness = 255; brightness >= 0; brightness--) {
      analogWrite(lightsPin, brightness);
      delay(fadeDelay); // Adjust fade speed
    }
  }
}