/*

 * Copyright (c) 2015, 2016, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

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 */

package jdk.internal.jimage.decompressor;

import java.io.ByteArrayInputStream;

import java.io.IOException;

import java.nio.ByteOrder;

import java.nio.charset.StandardCharsets;

import java.util.HashMap;

import java.util.Map;

import java.util.Objects;

import java.util.Properties;

import jdk.internal.jimage.decompressor.ResourceDecompressor.StringsProvider;

/**

 * Entry point to decompress resources.

 *

 * @implNote This class needs to maintain JDK 8 source compatibility.

 *

 * It is used internally in the JDK to implement jimage/jrtfs access,

 * but also compiled and delivered as part of the jrtfs.jar to support access

 * to the jimage file provided by the shipped JDK by tools running on JDK 8.

 */

public final class Decompressor {

    private final Map<Integer, ResourceDecompressor> pluginsCache = new HashMap<>();

    public Decompressor() {

    }

    /**

     * Decompress a resource.

     * @param order Byte order.

     * @param provider Strings provider

     * @param content The resource content to uncompress.

     * @return A fully uncompressed resource.

     * @throws IOException

     */

    public byte[] decompressResource(ByteOrder order, StringsProvider provider,

            byte[] content) throws IOException {

        Objects.requireNonNull(order);

        Objects.requireNonNull(provider);

        Objects.requireNonNull(content);

        CompressedResourceHeader header;

        do {

            header = CompressedResourceHeader.readFromResource(order, content);

            if (header != null) {

                ResourceDecompressor decompressor =

                        pluginsCache.get(header.getDecompressorNameOffset());

                if (decompressor == null) {

                    String pluginName =

                            provider.getString(header.getDecompressorNameOffset());

                    if (pluginName == null) {

                        throw new IOException("Plugin name not found");

                    }

                    String storedContent = header.getStoredContent(provider);

                    Properties props = new Properties();

                    if (storedContent != null) {

                        try (ByteArrayInputStream stream

                                = new ByteArrayInputStream(storedContent.

                                        getBytes(StandardCharsets.UTF_8));) {

                            props.loadFromXML(stream);

                        }

                    }

                    decompressor = ResourceDecompressorRepository.

                            newResourceDecompressor(props, pluginName);

                    if (decompressor == null) {

                        throw new IOException("Plugin not found: " + pluginName);

                    }

                    pluginsCache.put(header.getDecompressorNameOffset(), decompressor);

                }

                try {

                    content = decompressor.decompress(provider, content,

                            CompressedResourceHeader.getSize(), header.getUncompressedSize());

                } catch (Exception ex) {

                    throw new IOException(ex);

                }

            }

        } while (header != null);

        return content;

    }

}