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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.archivers.sevenz;

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

import org.apache.commons.compress.utils.ByteUtils;
import org.apache.commons.compress.utils.FlushShieldFilterOutputStream;
import org.tukaani.xz.LZMA2Options;
import org.tukaani.xz.LZMAInputStream;
import org.tukaani.xz.LZMAOutputStream;

class LZMADecoder extends CoderBase {
    LZMADecoder() {
        super(LZMA2Options.class, Number.class);
    }

    @Override
    InputStream decode(final String archiveName, final InputStream in, final long uncompressedLength,
            final Coder coder, final byte[] password) throws IOException {
        final byte propsByte = coder.properties[0];
        final int dictSize = getDictionarySize(coder);
        if (dictSize > LZMAInputStream.DICT_SIZE_MAX) {
            throw new IOException("Dictionary larger than 4GiB maximum size used in " + archiveName);
        }
        return new LZMAInputStream(in, uncompressedLength, propsByte, dictSize);
    }

    @SuppressWarnings("resource")
    @Override
    OutputStream encode(final OutputStream out, final Object opts)
        throws IOException {
        // NOOP as LZMAOutputStream throws an exception in flush
        return new FlushShieldFilterOutputStream(new LZMAOutputStream(out, getOptions(opts), false));
    }

    @Override
    byte[] getOptionsAsProperties(final Object opts) throws IOException {
        final LZMA2Options options = getOptions(opts);
        final byte props = (byte) ((options.getPb() * 5 + options.getLp()) * 9 + options.getLc());
        int dictSize = options.getDictSize();
        byte[] o = new byte[5];
        o[0] = props;
        ByteUtils.toLittleEndian(o, dictSize, 1, 4);
        return o;
    }

    @Override
    Object getOptionsFromCoder(final Coder coder, final InputStream in) throws IOException {
        final byte propsByte = coder.properties[0];
        int props = propsByte & 0xFF;
        int pb = props / (9 * 5);
        props -= pb * 9 * 5;
        int lp = props / 9;
        int lc = props - lp * 9;
        LZMA2Options opts = new LZMA2Options();
        opts.setPb(pb);
        opts.setLcLp(lc, lp);
        opts.setDictSize(getDictionarySize(coder));
        return opts;
    }

    private int getDictionarySize(final Coder coder) throws IllegalArgumentException {
        return (int) ByteUtils.fromLittleEndian(coder.properties, 1, 4);
    }

    private LZMA2Options getOptions(final Object opts) throws IOException {
        if (opts instanceof LZMA2Options) {
            return (LZMA2Options) opts;
        }
        final LZMA2Options options = new LZMA2Options();
        options.setDictSize(numberOptionOrDefault(opts));
        return options;
    }

    private int numberOptionOrDefault(final Object opts) {
        return numberOptionOrDefault(opts, LZMA2Options.DICT_SIZE_DEFAULT);
    }
}