/*
 * ConnectBot: simple, powerful, open-source SSH client for Android
 * Copyright 2007 Kenny Root, Jeffrey Sharkey
 *
 * Licensed 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 ch.ethz.ssh2.compression;

import com.jcraft.jzlib.JZlib;
import com.jcraft.jzlib.ZStream;

/**
 * @author Kenny Root
 *
 */
public class Zlib implements Compressor {
    static private final int DEFAULT_BUF_SIZE = 4096;
    static private final int LEVEL = 5;

    private ZStream deflate;
    private byte[] deflate_tmpbuf;

    private ZStream inflate;
    private byte[] inflate_tmpbuf;
    private byte[] inflated_buf;

    public Zlib() {
        deflate = new ZStream();
        inflate = new ZStream();
        deflate.deflateInit(LEVEL);
        inflate.inflateInit();
        deflate_tmpbuf = new byte[DEFAULT_BUF_SIZE];
        inflate_tmpbuf = new byte[DEFAULT_BUF_SIZE];
        inflated_buf = new byte[DEFAULT_BUF_SIZE];
    }

    public boolean canCompressPreauth() {
        return true;
    }

    public int getBufferSize() {
        return DEFAULT_BUF_SIZE;
    }

    public int compress(byte[] buf, int start, int len, byte[] output) {
        deflate.next_in = buf;
        deflate.next_in_index = start;
        deflate.avail_in = len - start;

        if ((buf.length + 1024) > deflate_tmpbuf.length) {
            deflate_tmpbuf = new byte[buf.length + 1024];
        }

        deflate.next_out = deflate_tmpbuf;
        deflate.next_out_index = 0;
        deflate.avail_out = output.length;

        if (deflate.deflate(JZlib.Z_PARTIAL_FLUSH) != JZlib.Z_OK) {
            System.err.println("compress: compression failure");
        }

        if (deflate.avail_in > 0) {
            System.err.println("compress: deflated data too large");
        }

        int outputlen = output.length - deflate.avail_out;
        System.arraycopy(deflate_tmpbuf, 0, output, 0, outputlen);
        return outputlen;
    }

    public byte[] uncompress(byte[] buffer, int start, int[] length) {
        int inflated_end = 0;
        inflate.next_in = buffer;
        inflate.next_in_index = start;
        inflate.avail_in = length[0];

        while (true) {
            inflate.next_out = inflate_tmpbuf;
            inflate.next_out_index = 0;
            inflate.avail_out = DEFAULT_BUF_SIZE;
            int status = inflate.inflate(JZlib.Z_PARTIAL_FLUSH);

            switch (status) {
                case JZlib.Z_OK:
                    if (inflated_buf.length < inflated_end + DEFAULT_BUF_SIZE
                            - inflate.avail_out) {
                        byte[] foo = new byte[inflated_end + DEFAULT_BUF_SIZE
                                              - inflate.avail_out];
                        System.arraycopy(inflated_buf, 0, foo, 0, inflated_end);
                        inflated_buf = foo;
                    }

                    System.arraycopy(inflate_tmpbuf, 0, inflated_buf, inflated_end,
                                     DEFAULT_BUF_SIZE - inflate.avail_out);
                    inflated_end += (DEFAULT_BUF_SIZE - inflate.avail_out);
                    length[0] = inflated_end;
                    break;

                case JZlib.Z_BUF_ERROR:
                    if (inflated_end > buffer.length - start) {
                        byte[] foo = new byte[inflated_end + start];
                        System.arraycopy(buffer, 0, foo, 0, start);
                        System.arraycopy(inflated_buf, 0, foo, start, inflated_end);
                        buffer = foo;
                    }
                    else {
                        System.arraycopy(inflated_buf, 0, buffer, start,
                                         inflated_end);
                    }

                    length[0] = inflated_end;
                    return buffer;

                default:
                    System.err.println("uncompress: inflate returnd " + status);
                    return null;
            }
        }
    }
}