#include <qpdf/Pl_DCT.hh>

#include <qpdf/QUtil.hh>
#include <qpdf/QTC.hh>
#include <setjmp.h>
#include <string>
#include <stdexcept>
#include <cstdlib>

#if BITS_IN_JSAMPLE != 8
# error "qpdf does not support libjpeg built with BITS_IN_JSAMPLE != 8"
#endif

struct qpdf_jpeg_error_mgr
{
    struct jpeg_error_mgr pub;
    jmp_buf jmpbuf;
    std::string msg;
};

static void
error_handler(j_common_ptr cinfo)
{
    qpdf_jpeg_error_mgr* jerr =
        reinterpret_cast<qpdf_jpeg_error_mgr*>(cinfo->err);
    char buf[JMSG_LENGTH_MAX];
    (*cinfo->err->format_message)(cinfo, buf);
    jerr->msg = buf;
    longjmp(jerr->jmpbuf, 1);
}

Pl_DCT::Pl_DCT(char const* identifier, Pipeline* next) :
    Pipeline(identifier, next),
    action(a_decompress),
    buf("DCT compressed image")
{
}

Pl_DCT::Pl_DCT(char const* identifier, Pipeline* next,
               JDIMENSION image_width,
               JDIMENSION image_height,
               int components,
               J_COLOR_SPACE color_space,
               CompressConfig* config_callback) :
    Pipeline(identifier, next),
    action(a_compress),
    buf("DCT uncompressed image"),
    image_width(image_width),
    image_height(image_height),
    components(components),
    color_space(color_space),
    config_callback(config_callback)
{
}

Pl_DCT::~Pl_DCT()
{
}

void
Pl_DCT::write(unsigned char* data, size_t len)
{
    this->buf.write(data, len);
}

void
Pl_DCT::finish()
{
    this->buf.finish();

    // Using a PointerHolder<Buffer> here and passing it into compress
    // and decompress causes a memory leak with setjmp/longjmp. Just
    // use a pointer and delete it.
    Buffer* b = this->buf.getBuffer();
    if (b->getSize() == 0)
    {
        // Special case: empty data will never succeed and probably
        // means we're calling finish a second time from an exception
        // handler.
        delete b;
        this->getNext()->finish();
        return;
    }

    struct jpeg_compress_struct cinfo_compress;
    struct jpeg_decompress_struct cinfo_decompress;
    struct qpdf_jpeg_error_mgr jerr;

    cinfo_compress.err = jpeg_std_error(&(jerr.pub));
    cinfo_decompress.err = jpeg_std_error(&(jerr.pub));
    jerr.pub.error_exit = error_handler;

    bool error = false;
    // The jpeg library is a "C" library, so we use setjmp and longjmp
    // for exception handling.
    if (setjmp(jerr.jmpbuf) == 0)
    {
        try
        {
            if (this->action == a_compress)
            {
                compress(reinterpret_cast<void*>(&cinfo_compress), b);
            }
            else
            {
                decompress(reinterpret_cast<void*>(&cinfo_decompress), b);
            }
        }
        catch (std::exception& e)
        {
            // Convert an exception back to a longjmp so we can ensure
            // that the right cleanup happens. This will get converted
            // back to an exception.
            jerr.msg = e.what();
            longjmp(jerr.jmpbuf, 1);
        }
    }
    else
    {
        error = true;
    }
    delete b;

    if (this->action == a_compress)
    {
        jpeg_destroy_compress(&cinfo_compress);
    }
    if (this->action == a_decompress)
    {
        jpeg_destroy_decompress(&cinfo_decompress);
    }
    if (error)
    {
        throw std::runtime_error(jerr.msg);
    }
}

struct dct_pipeline_dest
{
    struct jpeg_destination_mgr pub; /* public fields */
    unsigned char* buffer;
    size_t size;
    Pipeline* next;
};

static void
init_pipeline_destination(j_compress_ptr)
{
}

static boolean
empty_pipeline_output_buffer(j_compress_ptr cinfo)
{
    QTC::TC("libtests", "Pl_DCT empty_pipeline_output_buffer");
    dct_pipeline_dest* dest =
        reinterpret_cast<dct_pipeline_dest*>(cinfo->dest);
    dest->next->write(dest->buffer, dest->size);
    dest->pub.next_output_byte = dest->buffer;
    dest->pub.free_in_buffer = dest->size;
    return TRUE;
}

static void
term_pipeline_destination(j_compress_ptr cinfo)
{
    QTC::TC("libtests", "Pl_DCT term_pipeline_destination");
    dct_pipeline_dest* dest =
        reinterpret_cast<dct_pipeline_dest*>(cinfo->dest);
    dest->next->write(dest->buffer, dest->size - dest->pub.free_in_buffer);
}

static void
jpeg_pipeline_dest(j_compress_ptr cinfo,
                   unsigned char* outbuffer, size_t size,
                   Pipeline* next)
{
    cinfo->dest = static_cast<struct jpeg_destination_mgr *>(
        (*cinfo->mem->alloc_small)(reinterpret_cast<j_common_ptr>(cinfo),
                                   JPOOL_PERMANENT,
                                   sizeof(dct_pipeline_dest)));
    dct_pipeline_dest* dest =
        reinterpret_cast<dct_pipeline_dest*>(cinfo->dest);
    dest->pub.init_destination = init_pipeline_destination;
    dest->pub.empty_output_buffer = empty_pipeline_output_buffer;
    dest->pub.term_destination = term_pipeline_destination;
    dest->pub.next_output_byte = dest->buffer = outbuffer;
    dest->pub.free_in_buffer = dest->size = size;
    dest->next = next;
}

static void
init_buffer_source(j_decompress_ptr)
{
}

static boolean
fill_buffer_input_buffer(j_decompress_ptr)
{
    // The whole JPEG data is expected to reside in the supplied memory
    // buffer, so any request for more data beyond the given buffer size
    // is treated as an error.
    throw std::runtime_error("invalid jpeg data reading from buffer");
    return TRUE;
}

static void
skip_buffer_input_data(j_decompress_ptr cinfo, long num_bytes)
{
    if (num_bytes < 0)
    {
        throw std::runtime_error(
            "reading jpeg: jpeg library requested"
            " skipping a negative number of bytes");
    }
    size_t to_skip = static_cast<size_t>(num_bytes);
    if ((to_skip > 0) && (to_skip <= cinfo->src->bytes_in_buffer))
    {
        cinfo->src->next_input_byte += to_skip;
        cinfo->src->bytes_in_buffer -= to_skip;
    }
    else if (to_skip != 0)
    {
        cinfo->src->next_input_byte += cinfo->src->bytes_in_buffer;
        cinfo->src->bytes_in_buffer = 0;
    }
}

static void
term_buffer_source(j_decompress_ptr)
{
}

static void
jpeg_buffer_src(j_decompress_ptr cinfo, Buffer* buffer)
{
    cinfo->src = reinterpret_cast<jpeg_source_mgr *>(
        (*cinfo->mem->alloc_small)(reinterpret_cast<j_common_ptr>(cinfo),
                                   JPOOL_PERMANENT,
                                   sizeof(jpeg_source_mgr)));

    jpeg_source_mgr* src = cinfo->src;
    src->init_source = init_buffer_source;
    src->fill_input_buffer = fill_buffer_input_buffer;
    src->skip_input_data = skip_buffer_input_data;
    src->resync_to_restart = jpeg_resync_to_restart; /* use default method */
    src->term_source = term_buffer_source;
    src->bytes_in_buffer = buffer->getSize();
    src->next_input_byte = buffer->getBuffer();
}

void
Pl_DCT::compress(void* cinfo_p, Buffer* b)
{
    struct jpeg_compress_struct* cinfo =
        reinterpret_cast<jpeg_compress_struct*>(cinfo_p);

#if ((defined(__GNUC__) && ((__GNUC__ * 100) + __GNUC_MINOR__) >= 406) || \
     defined(__clang__))
#       pragma GCC diagnostic push
#       pragma GCC diagnostic ignored "-Wold-style-cast"
#endif
    jpeg_create_compress(cinfo);
#if ((defined(__GNUC__) && ((__GNUC__ * 100) + __GNUC_MINOR__) >= 406) || \
     defined(__clang__))
#       pragma GCC diagnostic pop
#endif
    static int const BUF_SIZE = 65536;
    PointerHolder<unsigned char> outbuffer_ph(
        true, new unsigned char[BUF_SIZE]);
    unsigned char* outbuffer = outbuffer_ph.getPointer();
    jpeg_pipeline_dest(cinfo, outbuffer, BUF_SIZE, this->getNext());

    cinfo->image_width = this->image_width;
    cinfo->image_height = this->image_height;
    cinfo->input_components = this->components;
    cinfo->in_color_space = this->color_space;
    jpeg_set_defaults(cinfo);
    if (this->config_callback)
    {
        this->config_callback->apply(cinfo);
    }

    jpeg_start_compress(cinfo, TRUE);

    int width = cinfo->image_width * cinfo->input_components;
    size_t expected_size =
        cinfo->image_height * cinfo->image_width * cinfo->input_components;
    if (b->getSize() != expected_size)
    {
        throw std::runtime_error(
            "Pl_DCT: image buffer size = " +
            QUtil::int_to_string(b->getSize()) + "; expected size = " +
            QUtil::int_to_string(expected_size));
    }
    JSAMPROW row_pointer[1];
    unsigned char* buffer = b->getBuffer();
    while (cinfo->next_scanline < cinfo->image_height)
    {
        // We already verified that the buffer is big enough.
        row_pointer[0] = &buffer[cinfo->next_scanline * width];
        (void) jpeg_write_scanlines(cinfo, row_pointer, 1);
    }
    jpeg_finish_compress(cinfo);
    this->getNext()->finish();
}

void
Pl_DCT::decompress(void* cinfo_p, Buffer* b)
{
    struct jpeg_decompress_struct* cinfo =
        reinterpret_cast<jpeg_decompress_struct*>(cinfo_p);

#if ((defined(__GNUC__) && ((__GNUC__ * 100) + __GNUC_MINOR__) >= 406) || \
     defined(__clang__))
#       pragma GCC diagnostic push
#       pragma GCC diagnostic ignored "-Wold-style-cast"
#endif
    jpeg_create_decompress(cinfo);
#if ((defined(__GNUC__) && ((__GNUC__ * 100) + __GNUC_MINOR__) >= 406) || \
     defined(__clang__))
#       pragma GCC diagnostic pop
#endif
    jpeg_buffer_src(cinfo, b);

    (void) jpeg_read_header(cinfo, TRUE);
    (void) jpeg_calc_output_dimensions(cinfo);

    int width = cinfo->output_width * cinfo->output_components;
    JSAMPARRAY buffer = (*cinfo->mem->alloc_sarray)
        (reinterpret_cast<j_common_ptr>(cinfo), JPOOL_IMAGE, width, 1);

    (void) jpeg_start_decompress(cinfo);
    while (cinfo->output_scanline < cinfo->output_height)
    {
        (void) jpeg_read_scanlines(cinfo, buffer, 1);
        this->getNext()->write(reinterpret_cast<unsigned char*>(buffer[0]),
                               width * sizeof(buffer[0][0]));
    }
    (void) jpeg_finish_decompress(cinfo);
    this->getNext()->finish();
}
