package Model ;

// Class which can instantiate objects which can run in separate threads.
//      We can instantiate an object of this class,
//      create a new thread,
//      pass the thread this object,
//      and run 
public class SwingWorker<ReturnType, V> extends Object implements Runnable
{
    private int idNum    = 0 ;  // Object ID.
    private int counter  = 0 ;  // Count up.

    private Thread           worker      = null ;   // Thread for this object.
    private volatile boolean requestStop = false ;  // Request thread stop.

    public SwingWorker()
    {
    }

    // Construct this object.
    public SwingWorker( int objectID )
    {
        idNum = objectID ;
        counter = 0 ;
    }

    // All background thread activity happens here.  Initiated by model.execute().
    public ReturnType doInBackground() 
    {
        // Periodically check for interrupt signal.
        while (!requestStop)
        {
            System.out.println( "Thread " + idNum + " running.  Counter = " + counter ) ;

            // Catch the exception generated if interrupted during sleep or wait.
            try
            {
                long time = System.currentTimeMillis();

                // Spin lock.
                while ( System.currentTimeMillis() - time < 500 &&
                        !requestStop )
                {
                }

                ++counter ;
                
                if (requestStop)
                {
                    System.out.println( "Thread interrupted during work." ) ;
                }
                else
                {
                    // Sleep
                    int randomTimeMs = (int)(0.5 + 1000.0 * Math.random() ) ;

                    System.out.println( "Thread sleeping " + randomTimeMs + " ms" ) ;
                    worker.sleep( randomTimeMs ) ;
                }
            }
            catch( InterruptedException e )
            {
                // Thread interrupted during sleep or wait.
                System.out.println( "Thread interrupted during wait/sleep." ) ;
            }

        } // end while

        return (ReturnType) null ;
    }

    // Starts a thread executing which runs the function doInBackground().
    // returns immediately.
    void execute()
    {
        // Start a thread going on this object.
        worker = new Thread( this ) ;

        System.out.println( "Starting new thread..." );

        worker.start() ;
    }

    // Called when doInBackground() completes.
    public void done() 
    {
        System.out.println( "Thread exiting run(), stop = " + requestStop );
    }

    // Run method for the thread.
    public void run()
    {
        doInBackground() ;
        done() ;
    }

    void stop()
    {
        System.out.println( "Asking thread to stop..." );
        requestStop = true ;

        worker.interrupt() ;
        
    }
}