#include "compression.h"
#include "minilzo.h"

#ifdef Q_OS_WIN
#include "xcompress.h"
#endif

// libmspack for LZX decompression
extern "C" {
#include "mspack/mspack.h"
#include "mspack/lzx.h"
}

#include <QLibrary>
#include <QDebug>
#include <QFile>
#include <QDir>
#include <QProcess>
#include <QtEndian>
#include <cstdio>

// ============================================================================
// Memory-based mspack_system for LZX decompression
// ============================================================================

struct MemoryFile {
    const unsigned char* data;
    size_t size;
    size_t pos;
    size_t rest;         // Remaining bytes in current block (Xbox 360 LZX)
    QByteArray* output;  // For write operations
};

static struct mspack_file* mem_open(struct mspack_system* /*self*/, const char* filename, int mode) {
    // filename is actually a pointer to our MemoryFile struct
    (void)mode;
    return reinterpret_cast<struct mspack_file*>(const_cast<char*>(filename));
}

static void mem_close(struct mspack_file* /*file*/) {
    // Nothing to do - we don't own the memory
}

// Simple mem_read without block headers - for raw LZX streams
static int mem_read_raw(struct mspack_file* file, void* buffer, int bytes) {
    MemoryFile* mf = reinterpret_cast<MemoryFile*>(file);
    if (!mf || !mf->data) return -1;

    size_t remaining = mf->size - mf->pos;
    size_t toRead = static_cast<size_t>(bytes);
    if (toRead > remaining) toRead = remaining;
    if (toRead == 0) return 0;

    memcpy(buffer, mf->data + mf->pos, toRead);
    mf->pos += toRead;

    return static_cast<int>(toRead);
}

// UE Viewer / Xbox 360 LZX block format with per-block headers
static int mem_read_xbox(struct mspack_file* file, void* buffer, int bytes) {
    MemoryFile* mf = reinterpret_cast<MemoryFile*>(file);
    if (!mf || !mf->data) return -1;

    // UE Viewer / Xbox 360 LZX block format:
    // Each block has a header:
    // - If first byte is 0xFF: 5-byte header (0xFF + 2-byte uncompressed BE + 2-byte compressed BE)
    // - Otherwise: 2-byte compressed size header (BE)
    if (mf->rest == 0) {
        // Need to read next block header
        if (mf->pos >= mf->size) return 0;  // EOF

        if (mf->data[mf->pos] == 0xFF) {
            // 5-byte header: [0]=0xFF, [1,2]=uncompressed size (BE), [3,4]=compressed size (BE)
            if (mf->pos + 5 > mf->size) return 0;
            mf->rest = (static_cast<size_t>(mf->data[mf->pos + 3]) << 8) |
                       (static_cast<size_t>(mf->data[mf->pos + 4]));
            mf->pos += 5;
        } else {
            // 2-byte header: [0,1]=compressed size (BE)
            if (mf->pos + 2 > mf->size) return 0;
            mf->rest = (static_cast<size_t>(mf->data[mf->pos + 0]) << 8) |
                       (static_cast<size_t>(mf->data[mf->pos + 1]));
            mf->pos += 2;
        }

        // Clamp to remaining data
        if (mf->rest > mf->size - mf->pos) {
            mf->rest = mf->size - mf->pos;
        }
    }

    // Read from current block
    size_t toRead = static_cast<size_t>(bytes);
    if (toRead > mf->rest) toRead = mf->rest;
    if (toRead == 0) return 0;

    memcpy(buffer, mf->data + mf->pos, toRead);
    mf->pos += toRead;
    mf->rest -= toRead;

    return static_cast<int>(toRead);
}

// Dead Rising 2 LZX format:
// Per-block: 4-byte BE block_size + 0xFF + 2-byte uncompressed BE + 2-byte compressed BE + LZX data
static int mem_read_deadrising(struct mspack_file* file, void* buffer, int bytes) {
    MemoryFile* mf = reinterpret_cast<MemoryFile*>(file);
    if (!mf || !mf->data) return -1;

    if (mf->rest == 0) {
        // Need to read next block header
        if (mf->pos >= mf->size) return 0;  // EOF

        // Dead Rising has 4-byte BE block size header before each block
        // Format: [0-3] = block_size (BE), [4] = 0xFF, [5-6] = uncompressed (BE), [7-8] = compressed (BE)
        if (mf->pos + 9 > mf->size) return 0;  // Need at least 9 bytes for headers

        // Skip the 4-byte block size header (we don't need it, we use the 2-byte compressed size)
        mf->pos += 4;

        // Now parse UE Viewer format
        if (mf->data[mf->pos] == 0xFF) {
            // 5-byte header: [0]=0xFF, [1,2]=uncompressed (BE), [3,4]=compressed (BE)
            if (mf->pos + 5 > mf->size) return 0;
            mf->rest = (static_cast<size_t>(mf->data[mf->pos + 3]) << 8) |
                       (static_cast<size_t>(mf->data[mf->pos + 4]));
            mf->pos += 5;
        } else {
            // 2-byte header: [0,1]=compressed size (BE)
            if (mf->pos + 2 > mf->size) return 0;
            mf->rest = (static_cast<size_t>(mf->data[mf->pos + 0]) << 8) |
                       (static_cast<size_t>(mf->data[mf->pos + 1]));
            mf->pos += 2;
        }

        // Clamp to remaining data
        if (mf->rest > mf->size - mf->pos) {
            mf->rest = mf->size - mf->pos;
        }
    }

    // Read from current block
    size_t toRead = static_cast<size_t>(bytes);
    if (toRead > mf->rest) toRead = mf->rest;
    if (toRead == 0) return 0;

    memcpy(buffer, mf->data + mf->pos, toRead);
    mf->pos += toRead;
    mf->rest -= toRead;

    return static_cast<int>(toRead);
}

// Default mem_read - use Dead Rising format
static int mem_read(struct mspack_file* file, void* buffer, int bytes) {
    return mem_read_deadrising(file, buffer, bytes);
}

static int mem_write(struct mspack_file* file, void* buffer, int bytes) {
    MemoryFile* mf = reinterpret_cast<MemoryFile*>(file);
    if (!mf || !mf->output) return -1;

    mf->output->append(reinterpret_cast<const char*>(buffer), bytes);
    return bytes;
}

static int mem_seek(struct mspack_file* file, off_t offset, int mode) {
    MemoryFile* mf = reinterpret_cast<MemoryFile*>(file);
    if (!mf) return -1;

    switch (mode) {
        case MSPACK_SYS_SEEK_START:
            mf->pos = static_cast<size_t>(offset);
            break;
        case MSPACK_SYS_SEEK_CUR:
            mf->pos += static_cast<size_t>(offset);
            break;
        case MSPACK_SYS_SEEK_END:
            mf->pos = mf->size + static_cast<size_t>(offset);
            break;
    }
    return 0;
}

static off_t mem_tell(struct mspack_file* file) {
    MemoryFile* mf = reinterpret_cast<MemoryFile*>(file);
    return mf ? static_cast<off_t>(mf->pos) : -1;
}

static void mem_message(struct mspack_file* /*file*/, const char* format, ...) {
    (void)format;
    // Suppress messages
}

static void* mem_alloc(struct mspack_system* /*self*/, size_t bytes) {
    return malloc(bytes);
}

static void mem_free(void* ptr) {
    free(ptr);
}

static void mem_copy(void* src, void* dest, size_t bytes) {
    memcpy(dest, src, bytes);
}

static struct mspack_system g_memSystem = {
    mem_open,
    mem_close,
    mem_read,
    mem_write,
    mem_seek,
    mem_tell,
    mem_message,
    mem_alloc,
    mem_free,
    mem_copy,
    nullptr  // null_ptr
};

// Static member initialization
QString Compression::s_quickBmsPath;

void Compression::setQuickBmsPath(const QString &path)
{
    s_quickBmsPath = path;
}

QString Compression::quickBmsPath()
{
    return s_quickBmsPath;
}

#ifdef Q_OS_WIN
QByteArray Compression::CompressXMem(const QByteArray &data)
{
    XMEMCODEC_PARAMETERS_LZX lzxParams = {};
    lzxParams.Flags = 0;
    lzxParams.WindowSize = 0x20000;
    lzxParams.CompressionPartitionSize = 0x80000;

    XMEMCOMPRESSION_CONTEXT ctx = nullptr;
    if (FAILED(XMemCreateCompressionContext(XMEMCODEC_LZX, &lzxParams, 0, &ctx)) || !ctx)
        return QByteArray();

    SIZE_T estimatedSize = data.size() + XCOMPRESS_LZX_BLOCK_GROWTH_SIZE_MAX;
    QByteArray output(static_cast<int>(estimatedSize), 0);
    SIZE_T actualSize = estimatedSize;

    HRESULT hr = XMemCompress(ctx, output.data(), &actualSize, data.constData(), data.size());
    XMemDestroyCompressionContext(ctx);

    if (FAILED(hr))
        return QByteArray();

    output.resize(static_cast<int>(actualSize));
    return output;
}
#else
QByteArray Compression::CompressXMem(const QByteArray &)
{
    qWarning() << "XMem compression not available on this platform";
    return {};
}
#endif

#ifdef Q_OS_WIN
QByteArray Compression::DecompressXMem(const QByteArray &data,
                                       int flags, int windowSize, int partSize)
{
    if (data.size() < 8)
        return {};

    // Read header identifier (big-endian in file)
    quint32 identifier = qFromBigEndian<quint32>(reinterpret_cast<const uchar*>(data.constData()));

    if (identifier == 0x0FF512EE) {
        // LZXNATIVE format - full header with codec params and block structure
        return DecompressXMemNative(data);
    } else if (identifier == 0x0FF512ED) {
        // LZXTDECODE format - simpler format
        return DecompressXMemTDecode(data, flags, windowSize, partSize);
    } else {
        // No header - treat as raw LZX data with provided params
        return DecompressXMemRaw(data, flags, windowSize, partSize);
    }
}

QByteArray Compression::DecompressXMemNative(const QByteArray &data)
{
    if (data.size() < 40) {
        qWarning() << "LZXNATIVE header too short";
        return {};
    }

    const uchar* ptr = reinterpret_cast<const uchar*>(data.constData());

    // Parse XCOMPRESS_FILE_HEADER_LZXNATIVE (all fields big-endian in file)
    // Offset 0-3: Identifier (already validated)
    // Offset 4-5: Version
    // Offset 6-7: Reserved
    // Offset 8-11: ContextFlags
    // Offset 12-15: CodecParams.Flags
    // Offset 16-19: CodecParams.WindowSize
    // Offset 20-23: CodecParams.CompressionPartitionSize
    // Offset 24-27: UncompressedSizeHigh
    // Offset 28-31: UncompressedSizeLow
    // Offset 32-35: CompressedSizeHigh
    // Offset 36-39: CompressedSizeLow
    // Offset 40-43: UncompressedBlockSize
    // Offset 44-47: CompressedBlockSizeMax

    XMEMCODEC_PARAMETERS_LZX lzxParams = {};
    lzxParams.Flags = qFromBigEndian<quint32>(ptr + 12);
    lzxParams.WindowSize = qFromBigEndian<quint32>(ptr + 16);
    lzxParams.CompressionPartitionSize = qFromBigEndian<quint32>(ptr + 20);

    quint64 uncompressedSize = (static_cast<quint64>(qFromBigEndian<quint32>(ptr + 24)) << 32) |
                                qFromBigEndian<quint32>(ptr + 28);
    quint32 uncompressedBlockSize = qFromBigEndian<quint32>(ptr + 40);

    qDebug() << "LZXNATIVE: windowSize=" << lzxParams.WindowSize
             << "partSize=" << lzxParams.CompressionPartitionSize
             << "uncompressedSize=" << uncompressedSize
             << "blockSize=" << uncompressedBlockSize;

    // Create decompression context
    XMEMDECOMPRESSION_CONTEXT ctx = nullptr;
    HRESULT hr = XMemCreateDecompressionContext(XMEMCODEC_LZX, &lzxParams, 0, &ctx);
    if (FAILED(hr) || !ctx) {
        qWarning() << "Failed to create LZX decompression context, hr=" << Qt::hex << hr;
        return {};
    }

    QByteArray output;
    output.reserve(static_cast<int>(uncompressedSize));

    // Data starts after 48-byte header, in blocks prefixed by 4-byte size
    int offset = 48;
    while (offset + 4 <= data.size()) {
        quint32 compressedBlockSize = qFromBigEndian<quint32>(ptr + offset);
        offset += 4;

        if (compressedBlockSize == 0 || offset + static_cast<int>(compressedBlockSize) > data.size())
            break;

        // Decompress this block
        QByteArray blockOut(uncompressedBlockSize, Qt::Uninitialized);
        SIZE_T destSize = blockOut.size();
        SIZE_T srcSize = compressedBlockSize;

        hr = XMemDecompress(ctx, blockOut.data(), &destSize, ptr + offset, srcSize);
        if (FAILED(hr)) {
            qWarning() << "XMemDecompress block failed, hr=" << Qt::hex << hr;
            XMemDestroyDecompressionContext(ctx);
            return output; // Return what we have
        }

        output.append(blockOut.constData(), static_cast<int>(destSize));
        offset += compressedBlockSize;

        // Reset context for next block
        XMemResetDecompressionContext(ctx);
    }

    XMemDestroyDecompressionContext(ctx);
    return output;
}

QByteArray Compression::DecompressXMemTDecode(const QByteArray &data, int flags, int windowSize, int partSize)
{
    Q_UNUSED(flags);
    Q_UNUSED(windowSize);
    Q_UNUSED(partSize);

    if (data.size() < 8)
        return {};

    // LZXTDECODE (0x0FF512ED) - Use QuickBMS as external tool since xcompress64.dll is unreliable
    // Write temp file, run QuickBMS, read result

    QString tempDir = QDir::tempPath();
    QString inputFile = tempDir + "/xmem_input.bin";
    QString outputFile = tempDir + "/xmem_output.bin";
    QString bmsScript = tempDir + "/xmem_decomp.bms";

    // Write input data
    QFile inFile(inputFile);
    if (!inFile.open(QIODevice::WriteOnly)) {
        qWarning() << "Failed to create temp input file";
        return {};
    }
    inFile.write(data);
    inFile.close();

    // Write BMS script
    QFile scriptFile(bmsScript);
    if (!scriptFile.open(QIODevice::WriteOnly | QIODevice::Text)) {
        qWarning() << "Failed to create BMS script";
        return {};
    }
    scriptFile.write("comtype xmemdecompress\n"
                     "get SIZE asize\n"
                     "clog \"\" 0 SIZE SIZE\n");
    scriptFile.close();

    // Run QuickBMS
    QProcess proc;
    proc.setWorkingDirectory(tempDir);
    QString quickbmsExe = quickBmsPath();
    if (quickbmsExe.isEmpty()) {
        qWarning() << "QuickBMS path not configured";
        return {};
    }
    QStringList args = {"-o", "-O", outputFile, bmsScript, inputFile};

    proc.start(quickbmsExe, args);
    if (!proc.waitForFinished(30000)) {
        qWarning() << "QuickBMS timeout or failed to start:" << quickbmsExe;
        return {};
    }

    if (proc.exitCode() != 0) {
        qWarning() << "QuickBMS failed:" << proc.readAllStandardError();
        return {};
    }

    // Read output
    QFile outFile(outputFile);
    if (!outFile.open(QIODevice::ReadOnly)) {
        qWarning() << "Failed to read QuickBMS output";
        return {};
    }
    QByteArray result = outFile.readAll();
    outFile.close();

    // Cleanup
    QFile::remove(inputFile);
    QFile::remove(outputFile);
    QFile::remove(bmsScript);

    qDebug() << "TDECODE via QuickBMS:" << data.size() << "->" << result.size() << "bytes";
    return result;
}

QByteArray Compression::DecompressXMemRaw(const QByteArray &data, int flags, int windowSize, int partSize)
{
    if (data.isEmpty())
        return {};

    XMEMCODEC_PARAMETERS_LZX lzxParams = {};
    lzxParams.Flags = flags;
    lzxParams.WindowSize = windowSize;
    lzxParams.CompressionPartitionSize = partSize;

    XMEMDECOMPRESSION_CONTEXT ctx = nullptr;
    HRESULT hr = XMemCreateDecompressionContext(XMEMCODEC_LZX, &lzxParams, 0, &ctx);
    if (FAILED(hr) || !ctx) {
        qWarning() << "Failed to create raw LZX context";
        return {};
    }

    const uchar* nextIn = reinterpret_cast<const uchar*>(data.constData());
    SIZE_T availIn = data.size();

    QByteArray output;
    output.reserve(16 * 1024 * 1024);

    QByteArray scratch(0x10000, Qt::Uninitialized);

    while (availIn > 0) {
        SIZE_T inSize = availIn;
        SIZE_T outSize = scratch.size();

        hr = XMemDecompressStream(ctx, scratch.data(), &outSize, nextIn, &inSize);

        if (FAILED(hr)) {
            qWarning() << "XMemDecompressStream raw failed, hr=" << Qt::hex << hr;
            break;
        }

        if (inSize == 0 && outSize == 0)
            break;

        output.append(scratch.constData(), static_cast<int>(outSize));
        nextIn += inSize;
        availIn -= inSize;
    }

    XMemDestroyDecompressionContext(ctx);
    return output;
}
#else
// Non-Windows stub implementations
QByteArray Compression::DecompressXMem(const QByteArray &, int, int, int)
{
    qWarning() << "XMem decompression not available on this platform";
    return {};
}

QByteArray Compression::DecompressXMemNative(const QByteArray &)
{
    qWarning() << "XMem native decompression not available on this platform";
    return {};
}

QByteArray Compression::DecompressXMemTDecode(const QByteArray &, int, int, int)
{
    qWarning() << "XMem TDecode decompression not available on this platform";
    return {};
}

QByteArray Compression::DecompressXMemRaw(const QByteArray &, int, int, int)
{
    qWarning() << "XMem raw decompression not available on this platform";
    return {};
}
#endif

// ============================================================================
// lzxdhelper-style LZX decompression (UE Viewer/Gildor approach)
// Uses their exact mspack_file structure and read function
// ============================================================================

struct LzxHelperFile {
    unsigned char* buf;
    int bufSize;
    int pos;
    int rest;
};

// Simple raw read without block parsing (for testing)
static int lzx_helper_read_raw(struct mspack_file* file, void* buffer, int bytes) {
    LzxHelperFile* f = reinterpret_cast<LzxHelperFile*>(file);
    int remaining = f->bufSize - f->pos;
    if (bytes > remaining) bytes = remaining;
    if (bytes <= 0) return 0;
    memcpy(buffer, f->buf + f->pos, bytes);
    f->pos += bytes;
    return bytes;
}

// UE Viewer-style block read
static int lzx_helper_read_blocks(struct mspack_file* file, void* buffer, int bytes) {
    LzxHelperFile* f = reinterpret_cast<LzxHelperFile*>(file);

    if (!f->rest) {
        // Read block header
        if (f->pos >= f->bufSize) return 0;

        if (f->buf[f->pos] == 0xFF) {
            // [0]   = FF
            // [1,2] = uncompressed block size
            // [3,4] = compressed block size
            if (f->pos + 5 > f->bufSize) return 0;
            f->rest = (f->buf[f->pos + 3] << 8) | f->buf[f->pos + 4];
            f->pos += 5;
        } else {
            // [0,1] = compressed size
            if (f->pos + 2 > f->bufSize) return 0;
            f->rest = (f->buf[f->pos + 0] << 8) | f->buf[f->pos + 1];
            f->pos += 2;
        }
        if (f->rest > f->bufSize - f->pos)
            f->rest = f->bufSize - f->pos;
    }

    if (bytes > f->rest) bytes = f->rest;
    if (bytes <= 0) return 0;

    memcpy(buffer, f->buf + f->pos, bytes);
    f->pos += bytes;
    f->rest -= bytes;
    return bytes;
}

static int lzx_helper_read(struct mspack_file* file, void* buffer, int bytes) {
    // Use raw read (Dead Rising 2 data has no UE block headers inside)
    return lzx_helper_read_raw(file, buffer, bytes);
}

static int lzx_helper_write(struct mspack_file* file, void* buffer, int bytes) {
    LzxHelperFile* f = reinterpret_cast<LzxHelperFile*>(file);
    memcpy(f->buf + f->pos, buffer, bytes);
    f->pos += bytes;
    return bytes;
}

static void* lzx_helper_alloc(struct mspack_system*, size_t bytes) {
    return malloc(bytes);
}

static void lzx_helper_free(void* ptr) {
    free(ptr);
}

static void lzx_helper_copy(void* src, void* dst, size_t bytes) {
    memcpy(dst, src, bytes);
}

static struct mspack_system g_lzxHelperSystem = {
    nullptr,           // open
    nullptr,           // close
    lzx_helper_read,
    lzx_helper_write,
    nullptr,           // seek
    nullptr,           // tell
    nullptr,           // message
    lzx_helper_alloc,
    lzx_helper_free,
    lzx_helper_copy,
    nullptr
};

QByteArray Compression::DecompressDeadRisingLZX(const QByteArray &data)
{
    // Dead Rising 2 LZX format:
    // File Header (8 bytes):
    //   [0-3]  u32_be  total_uncompressed_size
    //   [4-7]  u32_be  window_size (0x8000 = 32KB)
    //
    // Per-Block (repeating):
    //   [0-3]  u32_be  block_size (includes UE header + LZX data)
    //   [4]    0xFF    marker
    //   [5-6]  u16_be  block_uncompressed_size
    //   [7-8]  u16_be  block_compressed_size
    //   [9+]   LZX compressed data
    //
    // Strip the 4-byte block headers and decompress as continuous stream.

    if (data.size() < 8) {
        qWarning() << "Dead Rising LZX data too short:" << data.size();
        return {};
    }

    const uchar* ptr = reinterpret_cast<const uchar*>(data.constData());

    // Parse file header (big-endian)
    quint32 uncompressedSize = qFromBigEndian<quint32>(ptr);

    // Sanity check
    if (uncompressedSize == 0 || uncompressedSize > 100 * 1024 * 1024) {
        qWarning() << "Dead Rising LZX: unreasonable uncompressed size:" << uncompressedSize;
        return {};
    }

    // Decompress each block independently and concatenate results
    QByteArray output;
    output.reserve(static_cast<int>(uncompressedSize));

    int offset = 8;
    while (output.size() < static_cast<int>(uncompressedSize) && offset + 4 < data.size()) {
        quint32 blockSize = qFromBigEndian<quint32>(ptr + offset);
        offset += 4;
        if (blockSize == 0 || offset + static_cast<int>(blockSize) > data.size()) break;

        // Parse UE header to get sizes
        const uchar* blockPtr = ptr + offset;
        int blockUncompressed = 0;
        int compressedSize = 0;
        int headerSize = 0;

        if (blockPtr[0] == 0xFF) {
            // 5-byte header: 0xFF + uncompressed(2) + compressed(2)
            blockUncompressed = (blockPtr[1] << 8) | blockPtr[2];
            compressedSize = (blockPtr[3] << 8) | blockPtr[4];
            headerSize = 5;
        } else {
            // 2-byte header: compressed(2) - uncompressed defaults to 32KB
            compressedSize = (blockPtr[0] << 8) | blockPtr[1];
            blockUncompressed = 0x8000;
            headerSize = 2;
        }

        // Don't exceed remaining expected output
        blockUncompressed = qMin(blockUncompressed,
                                 static_cast<int>(uncompressedSize) - output.size());

        if (compressedSize <= 0 || headerSize + compressedSize > static_cast<int>(blockSize)) {
            break;
        }

        // Extract raw LZX data for this block
        QByteArray blockData(reinterpret_cast<const char*>(blockPtr + headerSize), compressedSize);

        // Decompress this block with its own LZX context
        QByteArray blockOutput(blockUncompressed, Qt::Uninitialized);

        LzxHelperFile src, dst;
        src.buf = reinterpret_cast<unsigned char*>(blockData.data());
        src.bufSize = blockData.size();
        src.pos = 0;
        src.rest = 0;

        dst.buf = reinterpret_cast<unsigned char*>(blockOutput.data());
        dst.bufSize = blockUncompressed;
        dst.pos = 0;

        struct lzxd_stream* lzx = lzxd_init(
            &g_lzxHelperSystem,
            reinterpret_cast<struct mspack_file*>(&src),
            reinterpret_cast<struct mspack_file*>(&dst),
            15,             // window_bits=15 (32KB window)
            0,              // reset_interval
            256 * 1024,     // input_buffer_size
            blockUncompressed,
            0               // is_delta
        );

        if (!lzx) {
            break;
        }

        int err = lzxd_decompress(lzx, blockUncompressed);
        lzxd_free(lzx);

        if (err != MSPACK_ERR_OK) {
            break;
        }

        output.append(blockOutput.constData(), dst.pos);
        offset += static_cast<int>(blockSize);
    }

    return output.isEmpty() ? QByteArray{} : output;
}

quint32 Compression::CalculateAdler32Checksum(const QByteArray &data) {
    // Start with the initial value for Adler-32
    quint32 adler = adler32(0L, Z_NULL, 0);

    // Calculate Adler-32 checksum
    adler = adler32(adler, reinterpret_cast<const Bytef *>(data.constData()), data.size());

    return adler;
}

qint64 Compression::FindZlibOffset(const QByteArray &bytes)
{
    QDataStream stream(bytes);

    while (!stream.atEnd())
    {
        QByteArray testSegment = stream.device()->peek(2).toHex().toUpper();
        if (testSegment == "7801" ||
            testSegment == "785E" ||
            testSegment == "789C" ||
            testSegment == "78DA") {
            return stream.device()->pos();
        }
        stream.skipRawData(1);
    }
    return -1;
}

QByteArray Compression::StripHashBlocks(const QByteArray &raw,
                                        int dataChunkSize,
                                        int hashChunkSize)
{
    QByteArray cleaned;
    cleaned.reserve(raw.size());        // upper bound

    int p = 0;
    while (p < raw.size())
    {
        const int chunk = qMin(dataChunkSize, raw.size() - p);
        cleaned.append(raw.constData() + p, chunk);
        p += chunk;

        // skip hash bytes if they are still inside the buffer
        if (p < raw.size())
            p += qMin(hashChunkSize, raw.size() - p);
    }
    return cleaned;
}

QByteArray Compression::DecompressZLIB(const QByteArray &aCompressedData) {
    if (aCompressedData.isEmpty()) {
        return {};
    }

    z_stream strm{};
    strm.zalloc = Z_NULL;
    strm.zfree = Z_NULL;
    strm.opaque = Z_NULL;
    strm.avail_in = static_cast<uInt>(aCompressedData.size());
    strm.next_in = reinterpret_cast<Bytef*>(const_cast<char*>(aCompressedData.data()));

    if (inflateInit2(&strm, MAX_WBITS) != Z_OK) {
        qWarning() << "inflateInit2 failed";
        return {};
    }

    QByteArray decompressed;
    QByteArray buffer(fmin(strm.avail_in * 2, 4096), Qt::Uninitialized);

    int ret;
    do {
        strm.next_out = reinterpret_cast<Bytef*>(buffer.data());
        strm.avail_out = buffer.size();

        ret = inflate(&strm, Z_NO_FLUSH);

        if (strm.avail_out < buffer.size()) {
            decompressed.append(buffer.constData(), buffer.size() - strm.avail_out);
        }

        if (ret == Z_STREAM_END) {
            break;
        }

        if (ret == Z_BUF_ERROR && strm.avail_out == 0) {
            buffer.resize(buffer.size() * 2);
        } else if (ret != Z_OK) {
            size_t errorOffset = strm.total_in;
            qWarning() << "Zlib error:" << zError(ret)
                       << "at offset" << errorOffset
                       << "of" << aCompressedData.size() << "bytes";
            inflateEnd(&strm);
            return decompressed;
        }
    } while (ret != Z_STREAM_END);

    inflateEnd(&strm);
    return decompressed;
}

QByteArray Compression::DecompressZlibAuto(const QByteArray &aCompressedData) {
    if (aCompressedData.isEmpty())
        return {};

    z_stream strm{};
    strm.zalloc = Z_NULL;
    strm.zfree = Z_NULL;
    strm.opaque = Z_NULL;
    strm.avail_in = static_cast<uInt>(aCompressedData.size());
    strm.next_in = reinterpret_cast<Bytef*>(const_cast<char*>(aCompressedData.data()));

    // MAX_WBITS + 32 enables automatic header detection (zlib, gzip, or raw deflate)
    if (inflateInit2(&strm, MAX_WBITS + 32) != Z_OK) {
        qWarning() << "inflateInit2 (auto) failed";
        return {};
    }

    QByteArray decompressed;
    QByteArray buffer(fmin(strm.avail_in * 2, 4096), Qt::Uninitialized);

    int ret;
    do {
        strm.next_out = reinterpret_cast<Bytef*>(buffer.data());
        strm.avail_out = buffer.size();

        ret = inflate(&strm, Z_NO_FLUSH);

        if (strm.avail_out < buffer.size()) {
            decompressed.append(buffer.constData(), buffer.size() - strm.avail_out);
        }

        if (ret == Z_STREAM_END) {
            break;
        }

        if (ret == Z_BUF_ERROR && strm.avail_out == 0) {
            buffer.resize(buffer.size() * 2);
        } else if (ret != Z_OK) {
            qDebug() << "Zlib auto-detect error:" << zError(ret)
                     << "at offset" << strm.total_in
                     << "of" << aCompressedData.size() << "bytes";
            inflateEnd(&strm);
            return decompressed;  // Return partial data on error
        }
    } while (ret != Z_STREAM_END);

    inflateEnd(&strm);
    return decompressed;
}

QByteArray Compression::CompressZLIB(const QByteArray &aData) {
    return CompressZLIBWithSettings(aData);
}

QByteArray Compression::CompressZLIBWithSettings(const QByteArray &aData, int aCompressionLevel, int aWindowBits, int aMemLevel, int aStrategy, const QByteArray &aDictionary) {
    if (aData.isEmpty())
        return {};

    z_stream strm{};
    if (deflateInit2(&strm, aCompressionLevel, Z_DEFLATED, aWindowBits, aMemLevel, aStrategy) != Z_OK) {
        qWarning() << "Failed to initialize compression with custom settings.";
        return {};
    }

    if (!aDictionary.isEmpty()) {
        deflateSetDictionary(&strm, reinterpret_cast<const Bytef*>(aDictionary.constData()), aDictionary.size());
    }

    strm.next_in = reinterpret_cast<Bytef*>(const_cast<char*>(aData.data()));
    strm.avail_in = aData.size();

    QByteArray compressed;
    char buffer[4096];

    int ret;
    do {
        strm.next_out = reinterpret_cast<Bytef*>(buffer);
        strm.avail_out = sizeof(buffer);

        ret = deflate(&strm, strm.avail_in ? Z_NO_FLUSH : Z_FINISH);
        if (ret != Z_OK && ret != Z_STREAM_END) {
            qWarning() << "Compression error:" << zError(ret);
            deflateEnd(&strm);
            return {};
        }

        compressed.append(buffer, sizeof(buffer) - strm.avail_out);
    } while (ret != Z_STREAM_END);

    deflateEnd(&strm);
    return compressed;
}

QByteArray Compression::DecompressDeflate(const QByteArray &aCompressedData) {
    if (aCompressedData.isEmpty())
        return {};

    z_stream strm{};
    strm.next_in = reinterpret_cast<Bytef*>(const_cast<char*>(aCompressedData.data()));
    strm.avail_in = static_cast<uInt>(aCompressedData.size());

    // Negative window bits (-MAX_WBITS) indicate raw DEFLATE data.
    if (inflateInit2(&strm, -MAX_WBITS) != Z_OK) {
        qWarning() << "Failed to initialize DEFLATE for decompression.";
        return QByteArray();
    }

    QByteArray decompressed;
    char buffer[4096];

    int ret;
    do {
        strm.next_out = reinterpret_cast<Bytef*>(buffer);
        strm.avail_out = sizeof(buffer);

        ret = inflate(&strm, Z_NO_FLUSH);

        if (ret != Z_OK && ret != Z_STREAM_END) {
            qWarning() << "DEFLATE decompression error:" << zError(ret);
            inflateEnd(&strm);
            return QByteArray();
        }

        decompressed.append(buffer, sizeof(buffer) - strm.avail_out);
    } while (ret != Z_STREAM_END);

    inflateEnd(&strm);
    return decompressed;
}

QByteArray Compression::CompressDeflate(const QByteArray &aData) {
    return CompressDeflateWithSettings(aData);
}

QByteArray Compression::CompressDeflateWithSettings(const QByteArray &aData, int aCompressionLevel, int aWindowBits, int aMemLevel, int aStrategy, const QByteArray &aDictionary) {
    Q_UNUSED(aDictionary);

    if (aData.isEmpty())
        return QByteArray();

    z_stream strm{};

    // Negative window bits (-MAX_WBITS) indicate raw DEFLATE data.
    if (deflateInit2(&strm, aCompressionLevel, Z_DEFLATED, -aWindowBits, aMemLevel, aStrategy) != Z_OK) {
        qWarning() << "Failed to initialize DEFLATE for compression.";
        return QByteArray();
    }

    strm.next_in = reinterpret_cast<Bytef*>(const_cast<char*>(aData.data()));
    strm.avail_in = static_cast<uInt>(aData.size());

    QByteArray compressed;
    char buffer[4096];

    int ret;
    do {
        strm.next_out = reinterpret_cast<Bytef*>(buffer);
        strm.avail_out = sizeof(buffer);

        ret = deflate(&strm, strm.avail_in ? Z_NO_FLUSH : Z_FINISH);

        if (ret != Z_OK && ret != Z_STREAM_END) {
            qWarning() << "DEFLATE compression error:" << zError(ret);
            deflateEnd(&strm);
            return {};
        }

        compressed.append(buffer, sizeof(buffer) - strm.avail_out);
    } while (ret != Z_STREAM_END);

    deflateEnd(&strm);
    return compressed;
}

QByteArray Compression::DecompressLZO(const QByteArray &aCompressedData, quint32 aDestSize) {
    QByteArray dst;
    static bool ok = (lzo_init() == LZO_E_OK);
    if (!ok)
        throw std::runtime_error("lzo_init failed");

    dst = QByteArray(aDestSize, Qt::Uninitialized);
    lzo_uint out = aDestSize;

    int rc = lzo1x_decompress_safe(
        reinterpret_cast<const lzo_bytep>(aCompressedData.constData()),
        static_cast<lzo_uint>(aCompressedData.size()),
        reinterpret_cast<lzo_bytep>(dst.data()),
        &out,
        nullptr);

    if (rc != LZO_E_OK)
        throw std::runtime_error("LZO decompression error");

    // Accept partial success - resize to actual output if size differs
    if (out != aDestSize) {
        dst.resize(out);
    }

    return dst;
}

QByteArray Compression::DecompressOodle(const QByteArray &aCompressedData, quint32 aDecompressedSize) {
    return pDecompressOodle(aCompressedData, aCompressedData.size(), aDecompressedSize);
}

QByteArray Compression::CompressOodle(const QByteArray &aData) {
    quint32 maxSize = pGetOodleCompressedBounds(aData.length());
    QByteArray compressedData = pCompressOodle(aData, aData.length(),
                                               maxSize, OodleFormat::Kraken, OodleCompressionLevel::Optimal5);

    return compressedData.mid(0, maxSize);
}

quint32 Compression::pGetOodleCompressedBounds(quint32 aBufferSize) {
    return aBufferSize + 274 * ((aBufferSize + 0x3FFFF) / 0x400000);
}

QByteArray Compression::pCompressOodle(QByteArray aBuffer, quint32 aBufferSize, quint32 aOutputBufferSize, OodleFormat aformat, OodleCompressionLevel alevel) {
    QLibrary lib("../../../third_party/oodle_lib/dll/oo2core_8_win64.dll"); // adjust path if needed
    if (!lib.load()) {
        qDebug() << "Failed to load:" << lib.errorString();
        return QByteArray();
    }

    OodleLZ_CompressFunc OodleLZ_Compress = (OodleLZ_CompressFunc)lib.resolve("OodleLZ_Compress");

    if (!OodleLZ_Compress) {
        qDebug() << "Failed to resolve OodleLZ_Compress:" << lib.errorString();
        return QByteArray();
    }

    std::byte *outputBuffer = new std::byte[aOutputBufferSize];

    if (aBuffer.length() > 0 && aBufferSize > 0 && aOutputBufferSize > 0)
        OodleLZ_Compress(aformat, reinterpret_cast<std::byte*>(aBuffer.data()), aBufferSize, outputBuffer, alevel, 0, 0, 0);

    return QByteArray(reinterpret_cast<const char*>(outputBuffer), aOutputBufferSize);
}

QByteArray Compression::pDecompressOodle(const QByteArray &aBuffer,
                                         quint32 aBufferSize,
                                         quint32 aOutputBufferSize)
{
    QLibrary lib("../../../third_party/oodle_lib/dll/oo2core_8_win64.dll");
    if (!lib.load()) {
        qWarning() << "Failed to load Oodle DLL:" << lib.errorString();
        return {};
    }

    OodleLZ_DecompressFunc OodleLZ_Decompress =
        reinterpret_cast<OodleLZ_DecompressFunc>(lib.resolve("OodleLZ_Decompress"));
    if (!OodleLZ_Decompress) {
        qWarning() << "Failed to resolve OodleLZ_Decompress:" << lib.errorString();
        return {};
    }

    QByteArray out(aOutputBufferSize + 1, Qt::Uninitialized);

    if (aBuffer.isEmpty() || aBufferSize == 0 || aOutputBufferSize == 0) {
        qWarning() << "Invalid Oodle parameters (empty input or size 0)";
        return {};
    }

    int result = OodleLZ_Decompress(
        aBuffer.constData(),
        static_cast<int64_t>(aBufferSize),
        out.data(),
        static_cast<int64_t>(aOutputBufferSize),
        1,
        0,
        0,
        0,
        0,
        0,
        0,
        0,
        0,
        3);

    if (result < 0) {
        qWarning() << "OodleLZ_Decompress failed with code" << result;
        return {};
    }

    if (result > out.size()) {
        qWarning() << "Oodle returned more than expected:" << result
                    << "expected" << aOutputBufferSize;
        return out;
    }

    out.resize(result);

    return out;
}