DownloadHelper.java

/*******************************************************************************
 * Copyright (c) 2014, 2015 IBH SYSTEMS GmbH.
 * 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:
 *     IBH SYSTEMS GmbH - initial API and implementation
 *******************************************************************************/
package org.eclipse.packagedrone.repo.channel.util;

import java.io.IOException;
import java.io.InputStream;
import java.util.Optional;
import java.util.function.Function;

import javax.servlet.http.HttpServletResponse;

import org.eclipse.packagedrone.repo.MetaKey;
import org.eclipse.packagedrone.repo.channel.ArtifactInformation;
import org.eclipse.packagedrone.repo.channel.ChannelArtifactInformation;
import org.eclipse.packagedrone.repo.channel.ChannelNotFoundException;
import org.eclipse.packagedrone.repo.channel.ChannelService;
import org.eclipse.packagedrone.repo.channel.ReadableChannel;
import org.eclipse.packagedrone.repo.channel.ChannelService.By;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import com.google.common.io.ByteStreams;

public final class DownloadHelper
{
    private static final MetaKey KEY_MIME_TYPE = new MetaKey ( "mime", "type" );

    private final static Logger logger = LoggerFactory.getLogger ( DownloadHelper.class );

    private DownloadHelper ()
    {
    }

    public static final String APPLICATION_OCTET_STREAM = "application/octet-stream";

    public static void streamArtifact ( final HttpServletResponse response, final ChannelService service, final String channelId, final String artifactId, final String mimetype, final boolean download ) throws IOException
    {
        streamArtifact ( response, service, channelId, artifactId, mimetype, download, ArtifactInformation::getName );
    }

    public static void streamArtifact ( final HttpServletResponse response, final ChannelService service, final String channelId, final String artifactId, final Optional<String> mimetype, final boolean download, final Function<ArtifactInformation, String> nameFunc ) throws IOException
    {
        try
        {
            service.accessRun ( By.id ( channelId ), ReadableChannel.class, channel -> {

                final ArtifactInformation artifact = channel.getContext ().getArtifacts ().get ( artifactId );
                if ( artifact == null )
                {
                    response.setStatus ( HttpServletResponse.SC_NOT_FOUND );
                    response.setContentType ( "text/plain" );
                    response.getWriter ().format ( "Artifact '%s' in channel '%s' could not be found", artifact, channelId );
                    return;
                }

                streamArtifact ( response, artifact, mimetype, download, channel, nameFunc );
            } );
        }
        catch ( final ChannelNotFoundException e )
        {
            response.setStatus ( HttpServletResponse.SC_NOT_FOUND );
            response.setContentType ( "text/plain" );
            response.getWriter ().format ( "Channel '%s' could not be found", channelId );
        }
    }

    public static void streamArtifact ( final HttpServletResponse response, final ChannelService service, final String channelId, final String artifactId, final String mimetype, final boolean download, final Function<ArtifactInformation, String> nameFunc ) throws IOException
    {
        streamArtifact ( response, service, channelId, artifactId, Optional.ofNullable ( mimetype ), download, nameFunc );
    }

    public static boolean streamArtifact ( final HttpServletResponse response, final String artifactId, final Optional<String> mimetype, final boolean download, final ReadableChannel channel, final Function<ArtifactInformation, String> nameFunc ) throws IOException
    {
        final Optional<ChannelArtifactInformation> artifact = channel.getArtifact ( artifactId );
        if ( !artifact.isPresent () )
        {
            return false;
        }

        return channel.getContext ().stream ( artifactId, stream -> {
            streamArtifact ( response, artifact.get (), stream, mimetype, download, nameFunc );
        } );
    }

    public static boolean streamArtifact ( final HttpServletResponse response, final ArtifactInformation artifact, final Optional<String> mimetype, final boolean download, final ReadableChannel channel, final Function<ArtifactInformation, String> nameFunc ) throws IOException
    {
        return channel.getContext ().stream ( artifact.getId (), stream -> {
            streamArtifact ( response, artifact, stream, mimetype, download, nameFunc );
        } );
    }

    public static void streamArtifact ( final HttpServletResponse response, final ArtifactInformation artifact, final InputStream stream, final Optional<String> mimetype, final boolean download, final Function<ArtifactInformation, String> nameFunc ) throws IOException
    {
        final String mt = mimetype.orElseGet ( () -> evalMimeType ( artifact ) );

        response.setStatus ( HttpServletResponse.SC_OK );
        response.setContentType ( mt );
        response.setDateHeader ( "Last-Modified", artifact.getCreationInstant ().toEpochMilli () );
        response.setContentLengthLong ( artifact.getSize () );

        if ( download )
        {
            if ( nameFunc != null )
            {
                response.setHeader ( "Content-Disposition", String.format ( "attachment; filename=%s", nameFunc.apply ( artifact ) ) );
            }
            else
            {
                response.setHeader ( "Content-Disposition", String.format ( "attachment; filename=%s", artifact.getName () ) );
            }
        }

        final long size = ByteStreams.copy ( stream, response.getOutputStream () );
        logger.debug ( "Copyied {} bytes", size );
    }

    private static String evalMimeType ( final ArtifactInformation artifact )
    {
        final String mimetype = artifact.getMetaData ().get ( KEY_MIME_TYPE );
        return mimetype == null ? APPLICATION_OCTET_STREAM : mimetype;
    }

}