/*******************************************************************************
 * Copyright (c) 2007, 2008 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *		compeople AG (Stefan Liebig) - various ongoing maintenance
 *******************************************************************************/
package org.eclipse.equinox.internal.p2.artifact.repository;

import java.io.IOException;
import java.io.OutputStream;
import org.eclipse.core.runtime.*;
import org.eclipse.ecf.filetransfer.*;
import org.eclipse.ecf.filetransfer.events.*;
import org.eclipse.ecf.filetransfer.identity.FileCreateException;
import org.eclipse.ecf.filetransfer.identity.FileIDFactory;
import org.eclipse.ecf.filetransfer.service.IRetrieveFileTransferFactory;
import org.eclipse.equinox.internal.p2.core.helpers.LogHelper;
import org.eclipse.equinox.internal.provisional.p2.artifact.repository.IStateful;
import org.osgi.util.tracker.ServiceTracker;

/**
 * A transport implementation that uses ECF file transfer API.
 */
public class ECFTransport extends Transport {

	/**
	 * The singleton transport instance.
	 */
	private static ECFTransport instance;

	private final ServiceTracker retrievalFactoryTracker;

	/**
	 * Returns an initialized instance of ECFTransport
	 */
	public static synchronized ECFTransport getInstance() {
		if (instance == null) {
			instance = new ECFTransport();
		}
		return instance;
	}

	/**
	 * Private to avoid client instantiation.
	 */
	private ECFTransport() {
		retrievalFactoryTracker = new ServiceTracker(Activator.getContext(), IRetrieveFileTransferFactory.class.getName(), null);
		retrievalFactoryTracker.open();
	}

	protected IStatus convertToStatus(IFileTransferEvent event, Exception failure, long startTime) {
		long speed = DownloadStatus.UNKNOWN_RATE;
		if (event instanceof IIncomingFileTransferEvent) {
			long bytes = ((IIncomingFileTransferEvent) event).getSource().getBytesReceived();
			if (bytes > 0) {
				long elapsed = (System.currentTimeMillis() - startTime) / 1000;//in seconds
				if (elapsed == 0)
					elapsed = 1;
				speed = bytes / elapsed;
			}
		}
		DownloadStatus result = null;
		if (failure == null)
			result = new DownloadStatus(IStatus.OK, Activator.ID, Status.OK_STATUS.getMessage());
		else if (failure instanceof UserCancelledException)
			result = new DownloadStatus(IStatus.CANCEL, Activator.ID, failure.getMessage(), failure);
		else
			result = new DownloadStatus(IStatus.ERROR, Activator.ID, "Error during transfer", failure);
		result.setTransferRate(speed);
		return result;
	}

	public IStatus download(String toDownload, OutputStream target, IProgressMonitor monitor) {
		IRetrieveFileTransferFactory factory = (IRetrieveFileTransferFactory) retrievalFactoryTracker.getService();
		if (factory == null)
			return statusOn(target, new Status(IStatus.ERROR, Activator.ID, "ECF Transfer manager not available"));

		return transfer(factory.newInstance(), toDownload, target, monitor);
	}

	private IStatus transfer(final IRetrieveFileTransferContainerAdapter retrievalContainer, final String toDownload, final OutputStream target, final IProgressMonitor monitor) {
		final IStatus[] result = new IStatus[1];
		final long startTime = System.currentTimeMillis();
		IFileTransferListener listener = new IFileTransferListener() {
			public void handleTransferEvent(IFileTransferEvent event) {
				if (event instanceof IIncomingFileTransferReceiveStartEvent) {
					IIncomingFileTransferReceiveStartEvent rse = (IIncomingFileTransferReceiveStartEvent) event;
					try {
						if (target != null) {
							rse.receive(target);
						}
					} catch (IOException e) {
						IStatus status = convertToStatus(event, e, startTime);
						synchronized (result) {
							result[0] = status;
							result.notify();
						}
					}
				}
				if (event instanceof IIncomingFileTransferReceiveDataEvent) {
					IIncomingFileTransfer source = ((IIncomingFileTransferReceiveDataEvent) event).getSource();
					if (monitor != null) {
						if (monitor.isCanceled())
							source.cancel();
					}
				}
				if (event instanceof IIncomingFileTransferReceiveDoneEvent) {
					Exception exception = ((IIncomingFileTransferReceiveDoneEvent) event).getException();
					IStatus status = convertToStatus(event, exception, startTime);
					synchronized (result) {
						result[0] = status;
						result.notify();
					}
				}
			}
		};

		try {
			retrievalContainer.sendRetrieveRequest(FileIDFactory.getDefault().createFileID(retrievalContainer.getRetrieveNamespace(), toDownload), listener, null);
		} catch (IncomingFileTransferException e) {
			return statusOn(target, e.getStatus());
		} catch (FileCreateException e) {
			return statusOn(target, e.getStatus());
		}
		synchronized (result) {
			while (result[0] == null) {
				boolean logged = false;
				try {
					result.wait();
				} catch (InterruptedException e) {
					if (!logged)
						LogHelper.log(new Status(IStatus.WARNING, Activator.ID, "Unexpected interrupt while waiting on ECF transfer", e)); //$NON-NLS-1$
				}
			}
		}

		return statusOn(target, result[0]);
	}

	private static IStatus statusOn(OutputStream target, IStatus status) {
		if (target instanceof IStateful)
			((IStateful) target).setStatus(status);
		return status;
	}
}