#include <Servo.h>
#include <SoftwareSerial.h>

// Set up Bluetooth serial communication
SoftwareSerial bluetooth(2, 3);  // RX, TX

// Set up solenoid lock
int lockPin = 9;  // Use PWM pin 9 to control solenoid
boolean lockState = false;

// Set up servo motor and ultrasonic sensor
Servo myservo;  // create servo object to control a servo
int pos = 0;    // variable to store the servo position
const int trigPin = 12;    // define the pins for ultrasonic sensor
const int echoPin = 11;

void setup() {
  // Set up serial communication for debugging
  Serial.begin(9600);
  while (!Serial) {
    ; // Wait for serial port to connect
  }

  // Set up solenoid lock
  pinMode(lockPin, OUTPUT);
  digitalWrite(lockPin, LOW);

  // Set up servo motor and ultrasonic sensor
  myservo.attach(6);  // attaches the servo on pin 6 to the servo object
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);

  // Set up Bluetooth serial communication
  bluetooth.begin(9600);
  Serial.println("Bluetooth module is ready");
}

void loop() {
  // Check for incoming Bluetooth data
  if (bluetooth.available()) {
    char command = bluetooth.read();
    Serial.print("Received command: ");
    Serial.println(command);

    // If command is 'L', lock the Bin
    if (command == 'L') {
      digitalWrite(lockPin, HIGH);  // Apply power to solenoid
      lockState = true;  // Update lock state
      Serial.println("Bin locked");
    }

    // If command is 'U', unlock the Bin
    if (command == 'U') {
      digitalWrite(lockPin, LOW);  // Remove power from solenoid
      lockState = false;  // Update lock state
      Serial.println("Bin unlocked");
    }
  }

  // Check for changes in lock state
  if (lockState) {
    bluetooth.print("Locked");
  } else {
    bluetooth.print("Unlocked");
  }

  // Send a 10 microsecond pulse to the ultrasonic sensor to trigger a measurement
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);

  // Read the duration of the pulse from the echo pin
  long duration = pulseIn(echoPin, HIGH);

  // Calculate the distance in centimeters based on the speed of sound
  int cm = (duration/2) / 29.1;

  Serial.print(cm);
  Serial.println(" cm");

  // If the distance is less than a certain threshold, rotate the servo to open the lid of the garbage bin
  if (cm < 20) {
    for (pos = 0; pos <= 90; pos += 1) { // goes from 0 degrees to 90 degrees in steps of 1 degree
      myservo.write(pos);              // tell servo to go to position in variable 'pos'
      delay(15);     }
  }
}