package ecologylab.concurrent;

import java.io.IOException;

import ecologylab.generic.Continuation;
import ecologylab.generic.Debug;

/**
 * Closure that keeps state about a download, as it progresses.
 */
public class DownloadState<T extends Downloadable>
extends Debug
{
	T													downloadable;
	
	private Continuation<T>		continuation;
	private DownloadMonitor		downloadMonitor;
	private Thread						downloadingThread;

	private boolean						continued;

	private boolean						recycled;

	DownloadState(T downloadable, Continuation<T> dispatchTarget,DownloadMonitor downloadMonitor)
	{
		this.downloadable			= downloadable;
		this.continuation			= dispatchTarget;
		this.downloadMonitor	= downloadMonitor;
	}

	boolean shouldCancel()
	{
		boolean result				= downloadable.isRecycled();
		if (!result)
		{
			BasicSite site = downloadable.getDownloadSite();
			if (site != null)
				result						= site.isDown();
		}
		return result;
	}

	/**
	 * Do the work to download this.
	 * @throws IOException 
	 * 
	 * @throws Exception
	 */
	void performDownload() throws IOException
	{
		downloadingThread		= Thread.currentThread();
		//TODO need a lock here to prevent recycle() while downloading!!!!!!
		if (downloadable != null && !downloadable.isRecycled())
		{
			//Update site statistics if available
			BasicSite site = downloadable.getDownloadSite();
			if(site != null)
				site.beginActualDownload();
			downloadable.performDownload();
			if(site != null)
				site.countNormalDownload();
			//ajit-added below condition for documents in local repository
			//download monitor can't do it after return from here
			if(site != null && downloadable.getDownloadLocation().isFile())
				site.endDownload();
		}
	}
	protected synchronized void callContinuation()
	{
		if (!continued && !recycled)
		{
			//	 debug("dispatch()"+" "+downloadable+" -> "+dispatchTarget);
			continued		= true;
			downloadMonitor.dispatched++;
			if (continuation != null)
				continuation.callback(downloadable);
		}
	}

	@Override
	public String toString()
	{
		String downloadableString = downloadable == null ? "recycled" : downloadable.toString();
		return super.toString() + "["+downloadableString +" "+
		downloadingThread + "]";
	}
	
	public void recycle(boolean recycleDownloadable)
	{
		if (!recycled)
		{
			recycled			= true;
			
			if (recycleDownloadable)
				downloadable.recycle();
			downloadable	= null;
			continuation	= null;
			downloadMonitor	= null;
			downloadingThread	= null;
		}
	}

}