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Apache Commons Compress defines an API for working with compression and archive formats. These include bzip2, gzip, pack200, LZMA, XZ, Snappy, traditional Unix Compress, DEFLATE, DEFLATE64, LZ4, Brotli, Zstandard and ar, cpio, jar, tar, zip, dump, 7z, arj.

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/*
 *  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.commons.compress.harmony.unpack200;

import java.io.IOException;
import java.io.InputStream;

import org.apache.commons.compress.harmony.pack200.Codec;
import org.apache.commons.compress.harmony.pack200.Pack200Exception;
import org.apache.commons.compress.utils.IOUtils;

/**
 * Parses the file band headers (not including the actual bits themselves). At the end of this parse call, the input stream will be positioned at the start of
 * the file_bits themselves, and there will be Sum(file_size) bits remaining in the stream with BYTE1 compression. A decent implementation will probably just
 * stream the bytes out to the reconstituted Jar rather than caching them.
 */
public class FileBands extends BandSet {

    private byte[][] fileBits;

    private int[] fileModtime;

    private String[] fileName;

    private int[] fileOptions;

    private long[] fileSize;

    private final String[] cpUTF8;

    private InputStream in;

    /**
     * @param segment TODO
     */
    public FileBands(final Segment segment) {
        super(segment);
        this.cpUTF8 = segment.getCpBands().getCpUTF8();
    }

    public byte[][] getFileBits() {
        return fileBits;
    }

    public int[] getFileModtime() {
        return fileModtime;
    }

    public String[] getFileName() {
        return fileName;
    }

    public int[] getFileOptions() {
        return fileOptions;
    }

    public long[] getFileSize() {
        return fileSize;
    }

    // TODO: stream the file bits directly somehow
    public void processFileBits() throws IOException {
        // now read in the bytes
        final int numberOfFiles = header.getNumberOfFiles();
        fileBits = new byte[numberOfFiles][];
        for (int i = 0; i < numberOfFiles; i++) {
            final int size = (int) fileSize[i];
            fileBits[i] = IOUtils.readRange(in, size);
            final int read = fileBits[i].length;
            if (size != 0 && read < size) {
                throw new IOException("Expected to read " + size + " bytes but read " + read);
            }
        }
    }

    /*
     * (non-Javadoc)
     *
     * @see org.apache.commons.compress.harmony.unpack200.BandSet#unpack(java.io.InputStream)
     */
    @Override
    public void read(final InputStream in) throws IOException, Pack200Exception {
        final int numberOfFiles = header.getNumberOfFiles();
        final SegmentOptions options = header.getOptions();

        fileName = parseReferences("file_name", in, Codec.UNSIGNED5, numberOfFiles, cpUTF8);
        fileSize = parseFlags("file_size", in, numberOfFiles, Codec.UNSIGNED5, options.hasFileSizeHi());
        if (options.hasFileModtime()) {
            fileModtime = decodeBandInt("file_modtime", in, Codec.DELTA5, numberOfFiles);
        } else {
            fileModtime = new int[numberOfFiles];
        }
        if (options.hasFileOptions()) {
            fileOptions = decodeBandInt("file_options", in, Codec.UNSIGNED5, numberOfFiles);
        } else {
            fileOptions = new int[numberOfFiles];
        }
        this.in = in; // store for use by processFileBits(), which is called
        // later
    }

    @Override
    public void unpack() {

    }

}