import java.io.*;
import java.net.*;

/**
 * This class provides location awareness to the granularity of a room
 * inside a building based on the reception of 802.11 broadcasts and the
 * corresponding detection of ultrasound.  This class is intended to be used
 * by an application running on a mobile device.  If the mobile device moves
 * close to a desktop running the ServerBeacon class/application, it will
 * know that it is in the same room as the desktop based on the information
 * provided by this MobileClient class.
 * <p>
 * An application using this class needs to provide a reference to a
 * LocationTracker object in the MobileClient class's constructor so that
 * the MobileClient class can signal the LocationTracker object when a room
 * change has occurred.
 * <p>
 * The MobileClient class implements both an UltrasoundUpdateListener
 * and a DatagramUpdateListener so that it can be informed of ultrasound
 * detections and datagram receptions.
 *
 * @author Tony Offer
 * @author Chris Palistrant
 * @version 1.0
 */
public class MobileClient implements UltrasoundUpdateListener,
                                     DatagramUpdateListener {

    // Reference to the object/application that instantiated this MobileClient
    protected LocationTracker notifyApp = null;

	// Reference to the UltrasoundListenr used throughout this class
	protected UltrasoundListener usl;
    
    // This string identifies the current room in which this
    // MobileClient object perceives itself to exist.
    private String room = null;
    
	private static final long RECORD = 2000;

    /**
     * This is the only constructor for this class.  It takes a reference
     * to a LocationTracker object so that the MobileClient class
     * can notify the object when a room change has occurred.  No other
     * constructor is provided because the MobileClient class must have
     * access to a roomChanged() method.
     *
     * @param extApp    Reference to the LocationTracker object that
     *                  will receive room change notifications.
     */
    public MobileClient(LocationTracker extApp) {
	notifyApp = extApp;

	// Start a datagram listener thread that will notify this class of updates.
	// Create a new UltrasoundListener that will be used to 

	//usl = new UltrasoundListener(this, false);   // No debugging info
	usl = new UltrasoundListener(this, true);
	new DatagramListener(this).start();

    }

    /**
     * Callback method for the UltrasoundListener thread that receives
     * notifications of newly received ultrasound detections.  This
     * method attempts to correlate the time of the received ultrasound
     * detection with the time of one of the previously received
     * datagram transmissions in order to make a determination of room
     * location.
     *
     * @param timeDetected    The time (in milliseconds since January 1,
     *                        1970) at which the ultrasound was
     *                        received.
     */
    public void ultrasoundDetected(long timeDetected) {
        /*** TESTING ***/
		System.out.println("US Detected: " +
			   //new java.util.Date(timeDetected));
    		   timeDetected); 
    }

    /**
     * Callback method for the DatagramListener thread that receives
     * notifications of newly received datagram messages.  This method
     * stores the received datagram message and the time at which it was
     * received for later correlation with ultrasound detections.  If an
     * ultrasound detection is later correlated with the datagram
     * message received by this callback method, then the received
     * datagram message describes the current room location.
     *
     * @param timeDetected    The time (in milliseconds since January 1,
     *                        1970) at which the datagram message was
     *                        received.
     * @param message    The string that was transmitted in the datagram.
     */
    public void datagramDetected(String message, long timeDetected) {
		/*** TESTING ***/
		System.out.println("\"" + message + "\" Received: " +
			//new java.util.Date(timeDetected));
			timeDetected);
		// A datagram was detected so, the line should be analyzed for an 
		// appropriate period of time.
		usl.record(RECORD);
    }
}