/*
 * compression.cpp
 * Copyright 2008, Thorbjørn Lindeijer <thorbjorn@lindeijer.nl>
 *
 * This file is part of libtiled.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 *    1. Redistributions of source code must retain the above copyright notice,
 *       this list of conditions and the following disclaimer.
 *
 *    2. Redistributions in binary form must reproduce the above copyright
 *       notice, this list of conditions and the following disclaimer in the
 *       documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE CONTRIBUTORS ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
 * EVENT SHALL THE CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
 * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include "compression.h"

#include <zlib.h>
#include <QByteArray>
#include <QDebug>

using namespace Tiled;

// TODO: Improve error reporting by showing these errors in the user interface
static void logZlibError(int error)
{
    switch (error)
    {
        case Z_MEM_ERROR:
            qDebug() << "Out of memory while (de)compressing data!";
            break;
        case Z_VERSION_ERROR:
            qDebug() << "Incompatible zlib version!";
            break;
        case Z_NEED_DICT:
        case Z_DATA_ERROR:
            qDebug() << "Incorrect zlib compressed data!";
            break;
        default:
            qDebug() << "Unknown error while (de)compressing data!";
    }
}

QByteArray Tiled::decompress(const QByteArray &data, int expectedSize)
{
    QByteArray out;
    out.resize(expectedSize);
    z_stream strm;

    strm.zalloc = Z_NULL;
    strm.zfree = Z_NULL;
    strm.opaque = Z_NULL;
    strm.next_in = (Bytef *) data.data();
    strm.avail_in = data.length();
    strm.next_out = (Bytef *) out.data();
    strm.avail_out = out.size();

    int ret = inflateInit2(&strm, 15 + 32);

    if (ret != Z_OK) {
        logZlibError(ret);
        return QByteArray();
    }

    do {
        ret = inflate(&strm, Z_SYNC_FLUSH);

        switch (ret) {
            case Z_NEED_DICT:
            case Z_STREAM_ERROR:
                ret = Z_DATA_ERROR;
            case Z_DATA_ERROR:
            case Z_MEM_ERROR:
                inflateEnd(&strm);
                logZlibError(ret);
                return QByteArray();
        }

        if (ret != Z_STREAM_END) {
            int oldSize = out.size();
            out.resize(out.size() * 2);

            strm.next_out = (Bytef *)(out.data() + oldSize);
            strm.avail_out = oldSize;
        }
    }
    while (ret != Z_STREAM_END);

    if (strm.avail_in != 0) {
        logZlibError(Z_DATA_ERROR);
        return QByteArray();
    }

    const int outLength = out.size() - strm.avail_out;
    inflateEnd(&strm);

    out.resize(outLength);
    return out;
}

QByteArray Tiled::compress(const QByteArray &data, CompressionMethod method)
{
    QByteArray out;
    out.resize(1024);
    int err;
    z_stream strm;
    strm.zalloc = Z_NULL;
    strm.zfree = Z_NULL;
    strm.opaque = Z_NULL;
    strm.next_in = (Bytef *) data.data();
    strm.avail_in = data.length();
    strm.next_out = (Bytef *) out.data();
    strm.avail_out = out.size();

    const int windowBits = (method == Gzip) ? 15 + 16 : 15;

    err = deflateInit2(&strm, Z_DEFAULT_COMPRESSION, Z_DEFLATED, windowBits,
                       8, Z_DEFAULT_STRATEGY);
    if (err != Z_OK) {
        logZlibError(err);
        return QByteArray();
    }

    do {
        err = deflate(&strm, Z_FINISH);
        Q_ASSERT(err != Z_STREAM_ERROR);

        if (err == Z_OK) {
            // More output space needed
            int oldSize = out.size();
            out.resize(out.size() * 2);

            strm.next_out = (Bytef *)(out.data() + oldSize);
            strm.avail_out = oldSize;
        }
    } while (err == Z_OK);

    if (err != Z_STREAM_END) {
        logZlibError(err);
        deflateEnd(&strm);
        return QByteArray();
    }

    const int outLength = out.size() - strm.avail_out;
    deflateEnd(&strm);

    out.resize(outLength);
    return out;
}