// Define ultrasonic sensor pins
const int trigPin = 19;
const int echoPin = 18;
const int maxDistance = 40;

// Define PIR sensor pin
const int pirPin = 13;

// Define servo motor pin
const int servoPin = 15;

// Define servo motor angle range
const int servoMinAngle = 0;
const int servoMaxAngle = 180;

// Define rubbish bin capacity and current fill level
const int rubbishBinCapacity = 40;
int rubbishBinLevel = 0;

// Define person detection status
bool isPersonDetected = false;

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

  // Set ultrasonic sensor pins as input/output
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);

  // Set PIR sensor pin as input
  pinMode(pirPin, INPUT);

  // Set servo motor pin as output
  pinMode(servoPin, OUTPUT);

  // Move the servo motor to the initial position
  moveServo(servoMinAngle);
}

void loop() {
  // Read distance from the ultrasonic sensor
  long duration, distance;
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);
  duration = pulseIn(echoPin, HIGH);
  distance = duration * 0.034 / 2;

  // Limit the distance within the maximum distance range
  if (distance > maxDistance) {
    distance = maxDistance;
  }

  // Update the trash can fill level
  rubbishBinLevel = map(distance, 0, maxDistance, rubbishBinCapacity, 0);

  // Read the status of the PIR sensor
  isPersonDetected = digitalRead(pirPin);

  // Control the servo motor to open or close the rubbish bin lid based on the PIR sensor status
  if (isPersonDetected) {
    moveServo(servoMaxAngle);
  } else {
    moveServo(servoMinAngle);
  }

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

  // Calculate the rubbish bin fill level percentage
  int fillPercentage = map(distance, 0, maxDistance, 0, 100);

  // Output rubbish bin information
  Serial.print("Rubbish Bin Fill Level: ");
  Serial.print(fillPercentage);
  Serial.print("% fill level reached.\n");

  // Check the rubbish bin fill level and output the corresponding information
  if (fillPercentage >= 100) {
    Serial.println("The rubbish bin is full.");
  } else if (fillPercentage >= 75) {
    Serial.println("The rubbish bin is almost full.");
  } else if (fillPercentage >= 50) {
    Serial.println("The rubbish bin is half full.");
  } else if (fillPercentage >= 25) {
    Serial.println("The rubbish bin is partially full.");
  } else {
    Serial.println("The rubbish bin is not yet filled.");
  }
  Serial.println("\n");
  delay(3000);
}

// Control the servo motor angle
void moveServo(int angle) {
  angle = constrain(angle, servoMinAngle, servoMaxAngle);
  int pulseWidth = map(angle, 0, 180, 1000, 2000);
  digitalWrite(servoPin, HIGH);
  delayMicroseconds(pulseWidth);
  digitalWrite(servoPin, LOW);
  delay(20);
}