/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.wicket.util.resource;

import java.io.BufferedInputStream;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.time.Instant;
import java.util.zip.ZipEntry;
import java.util.zip.ZipOutputStream;
import org.apache.wicket.util.file.File;
import org.apache.wicket.util.lang.Args;
import org.apache.wicket.util.lang.Bytes;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;


/**
 * An IResourceStream that ZIPs a directory's contents on the fly
 * 
 * <p>
 * <b>NOTE 1.</b> As a future improvement, cache a map of generated ZIP files for every directory
 * and use a Watcher to detect modifications in this directory. Using ehcache would be good for
 * that, but it's not in Wicket dependencies yet. <b>No caching of the generated ZIP files is done
 * yet.</b>
 * </p>
 * 
 * <p>
 * <b>NOTE 2.</b> As a future improvement, implement getLastModified() and request
 * ResourceStreamRequestTarget to generate Last-Modified and Expires HTTP headers. <b>No HTTP cache
 * headers are provided yet</b>. See WICKET-385
 * </p>
 * 
 * @author <a href="mailto:jbq@apache.org">Jean-Baptiste Quenot</a>
 */
public class ZipResourceStream extends AbstractResourceStream
{
        private static final long serialVersionUID = 1L;

        private static final Logger log = LoggerFactory.getLogger(ZipResourceStream.class);

        private final transient ByteArrayOutputStream bytearray;

        /**
         * Construct.
         * 
         * @param dir
         *            The directory where to look for files. The directory itself will not be included
         *            in the ZIP.
         * @param recursive
         *            If true, all subdirs will be zipped as well
         */
        public ZipResourceStream(final File dir, final boolean recursive)
        {
                Args.notNull(dir, "dir");
                Args.isTrue(dir.isDirectory(), "Not a directory: '{}'", dir);

                bytearray = new ByteArrayOutputStream();
                try
                {
                        ZipOutputStream out = new ZipOutputStream(bytearray);
                        try
                        {
                                zipDir(dir, out, "", recursive);
                        } finally {
                                out.close();
                        }
                }
                catch (RuntimeException e)
                {
                        throw e;
                }
                catch (Exception e)
                {
                        throw new RuntimeException(e);
                }
        }

        /**
         * Construct. Until Wicket 1.4-RC3 recursive zip was not supported. In order not to change the
         * behavior, using this constructor will default to recursive == false.
         * 
         * @param dir
         *            The directory where to look for files. The directory itself will not be included
         *            in the ZIP.
         */
        public ZipResourceStream(final File dir)
        {
                this(dir, false);
        }

        /**
         * Recursive method for zipping the contents of a directory including nested directories.
         * 
         * @param dir
         *            dir to be zipped
         * @param out
         *            ZipOutputStream to write to
         * @param path
         *            Path to nested dirs (used in resursive calls)
         * @param recursive
         *            If true, all subdirs will be zipped as well
         * @throws IOException
         */
        private static void zipDir(final File dir, final ZipOutputStream out, final String path,
                final boolean recursive) throws IOException
        {
                Args.notNull(dir, "dir");
                Args.isTrue(dir.isDirectory(), "Not a directory: '{}'", dir);

                String[] files = dir.list();

                int BUFFER = 2048;
                BufferedInputStream origin;
                byte data[] = new byte[BUFFER];

                if (files != null)
                {
                        for (String file : files)
                        {
                                log.debug("Adding: '{}'", file);

                                File f = new File(dir, file);
                                if (f.isDirectory())
                                {
                                        if (recursive)
                                        {
                                                zipDir(f, out, path + f.getName() + "/", recursive);
                                        }
                                } else
                                {
                                        out.putNextEntry(new ZipEntry(path + f.getName()));

                                        FileInputStream fi = new FileInputStream(f);
                                        origin = new BufferedInputStream(fi, BUFFER);

                                        try
                                        {
                                                int count;
                                                while ((count = origin.read(data, 0, BUFFER)) != -1)
                                                {
                                                        out.write(data, 0, count);
                                                }
                                        } finally
                                        {
                                                origin.close();
                                        }
                                }
                        }
                }

                if (path.isEmpty())
                {
                        out.close();
                }
        }

        /**
         * @see org.apache.wicket.util.resource.IResourceStream#close()
         */
        @Override
        public void close() throws IOException
        {
        }

        /**
         * @see org.apache.wicket.util.resource.IResourceStream#getContentType()
         */
        @Override
        public String getContentType()
        {
                return null;
        }

        /**
         * @see org.apache.wicket.util.resource.IResourceStream#getInputStream()
         */
        @Override
        public InputStream getInputStream() throws ResourceStreamNotFoundException
        {
                return new ByteArrayInputStream(bytearray.toByteArray());
        }

        /**
         * @see org.apache.wicket.util.resource.AbstractResourceStream#length()
         */
        @Override
        public Bytes length()
        {
                return Bytes.bytes(bytearray.size());
        }

        /**
         * @see org.apache.wicket.util.resource.AbstractResourceStream#lastModifiedTime()
         */
        @Override
        public Instant lastModifiedTime()
        {
                return null;
        }
}