/*****************************************************************************
 *
 * This file is part of Mapnik (c++ mapping toolkit)
 *
 * Copyright (C) 2017 Artem Pavlenko
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 *
 *****************************************************************************/

// mapnik
#include <mapnik/debug.hpp>
#include <mapnik/image_reader.hpp>
#include <mapnik/util/char_array_buffer.hpp>
extern "C"
{
#include <tiffio.h>
}

// stl
#include <memory>
#include <fstream>

namespace mapnik { namespace impl {

static toff_t tiff_seek_proc(thandle_t handle, toff_t off, int whence)
{
    std::istream* in = reinterpret_cast<std::istream*>(handle);

    switch(whence)
    {
    case SEEK_SET:
        in->seekg(off, std::ios_base::beg);
        break;
    case SEEK_CUR:
        in->seekg(off, std::ios_base::cur);
        break;
    case SEEK_END:
        in->seekg(off, std::ios_base::end);
        break;
    }
    return static_cast<toff_t>(in->tellg());
}

static int tiff_close_proc(thandle_t)
{
    return 0;
}

static toff_t tiff_size_proc(thandle_t handle)
{
    std::istream* in = reinterpret_cast<std::istream*>(handle);
    std::ios::pos_type pos = in->tellg();
    in->seekg(0, std::ios::end);
    std::ios::pos_type len = in->tellg();
    in->seekg(pos);
    return static_cast<toff_t>(len);
}

static tsize_t tiff_read_proc(thandle_t handle, tdata_t buf, tsize_t size)
{
    std::istream * in = reinterpret_cast<std::istream*>(handle);
    std::streamsize request_size = size;
    if (static_cast<tsize_t>(request_size) != size)
        return static_cast<tsize_t>(-1);
    in->read(reinterpret_cast<char*>(buf), request_size);
    return static_cast<tsize_t>(in->gcount());
}

static tsize_t tiff_write_proc(thandle_t , tdata_t , tsize_t)
{
    return 0;
}

static void tiff_unmap_proc(thandle_t, tdata_t, toff_t)
{
}

static int tiff_map_proc(thandle_t, tdata_t* , toff_t*)
{
    return 0;
}

}

template <typename T>
class tiff_reader : public image_reader
{
    using tiff_ptr = std::shared_ptr<TIFF>;
    using source_type = T;
    using input_stream = std::istream;

    struct tiff_closer
    {
        void operator() (TIFF * tif)
        {
            if (tif != 0)
            {
                TIFFClose(tif);
            }
        }
    };

private:
    source_type source_;
    input_stream stream_;
    tiff_ptr tif_;
    int read_method_;
    int rows_per_strip_;
    int tile_width_;
    int tile_height_;
    std::size_t width_;
    std::size_t height_;
    boost::optional<box2d<double> > bbox_;
    unsigned bps_;
    unsigned sample_format_;
    unsigned photometric_;
    unsigned bands_;
    unsigned planar_config_;
    unsigned compression_;
    bool has_alpha_;
    bool is_tiled_;

public:
    enum TiffType {
        generic=1,
        stripped,
        tiled
    };
    explicit tiff_reader(std::string const& filename);
    tiff_reader(char const* data, std::size_t size);
    virtual ~tiff_reader();
    unsigned width() const final;
    unsigned height() const final;
    boost::optional<box2d<double> > bounding_box() const final;
    inline bool has_alpha() const final { return has_alpha_; }
    void read(unsigned x,unsigned y,image_rgba8& image) final;
    image_any read(unsigned x, unsigned y, unsigned width, unsigned height) final;
    // methods specific to tiff reader
    unsigned bits_per_sample() const { return bps_; }
    unsigned sample_format() const { return sample_format_; }
    unsigned photometric() const { return photometric_; }
    bool is_tiled() const { return is_tiled_; }
    unsigned tile_width() const { return tile_width_; }
    unsigned tile_height() const { return tile_height_; }
    unsigned rows_per_strip() const { return rows_per_strip_; }
    unsigned planar_config() const { return planar_config_; }
    unsigned compression() const { return compression_; }
private:
    tiff_reader(const tiff_reader&);
    tiff_reader& operator=(const tiff_reader&);
    void init();

    template <typename ImageData>
    void read_generic(std::size_t x,std::size_t y, ImageData & image);

    template <typename ImageData>
    void read_stripped(std::size_t x,std::size_t y, ImageData & image);

    template <typename ImageData>
    void read_tiled(std::size_t x,std::size_t y, ImageData & image);

    template <typename ImageData>
    image_any read_any_gray(std::size_t x, std::size_t y, std::size_t width, std::size_t height);

    TIFF* open(std::istream & input);
};

namespace
{

image_reader* create_tiff_reader(std::string const& filename)
{
    return new tiff_reader<std::filebuf>(filename);
}

image_reader* create_tiff_reader2(char const * data, std::size_t size)
{
    return new tiff_reader<mapnik::util::char_array_buffer>(data, size);
}

const bool registered = register_image_reader("tiff",create_tiff_reader);
const bool registered2 = register_image_reader("tiff", create_tiff_reader2);

}

template <typename T>
tiff_reader<T>::tiff_reader(std::string const& filename)
    : source_(),
      stream_(&source_),
      tif_(nullptr),
      read_method_(generic),
      rows_per_strip_(0),
      tile_width_(0),
      tile_height_(0),
      width_(0),
      height_(0),
      bps_(0),
      sample_format_(SAMPLEFORMAT_UINT),
      photometric_(0),
      bands_(1),
      planar_config_(PLANARCONFIG_CONTIG),
      compression_(COMPRESSION_NONE),
      has_alpha_(false),
      is_tiled_(false)
{
    source_.open(filename, std::ios_base::in | std::ios_base::binary);
    if (!stream_) throw image_reader_exception("TIFF reader: cannot open file "+ filename);
    init();
}

template <typename T>
tiff_reader<T>::tiff_reader(char const* data, std::size_t size)
    : source_(data, size),
      stream_(&source_),
      tif_(nullptr),
      read_method_(generic),
      rows_per_strip_(0),
      tile_width_(0),
      tile_height_(0),
      width_(0),
      height_(0),
      bps_(0),
      sample_format_(SAMPLEFORMAT_UINT),
      photometric_(0),
      bands_(1),
      planar_config_(PLANARCONFIG_CONTIG),
      compression_(COMPRESSION_NONE),
      has_alpha_(false),
      is_tiled_(false)
{
    if (!stream_) throw image_reader_exception("TIFF reader: cannot open image stream ");
    init();
}

template <typename T>
void tiff_reader<T>::init()
{
    // avoid calling TIFFs global structures
    TIFFSetWarningHandler(0);
    TIFFSetErrorHandler(0);

    TIFF* tif = open(stream_);

    if (!tif) throw image_reader_exception("Can't open tiff file");

    TIFFGetField(tif,TIFFTAG_BITSPERSAMPLE,&bps_);
    TIFFGetField(tif,TIFFTAG_SAMPLEFORMAT,&sample_format_);
    TIFFGetField(tif,TIFFTAG_PHOTOMETRIC,&photometric_);
    TIFFGetField(tif, TIFFTAG_SAMPLESPERPIXEL, &bands_);

    MAPNIK_LOG_DEBUG(tiff_reader) << "bits per sample: " << bps_ ;
    MAPNIK_LOG_DEBUG(tiff_reader) << "sample format: " << sample_format_ ;
    MAPNIK_LOG_DEBUG(tiff_reader) << "photometric: " << photometric_ ;
    MAPNIK_LOG_DEBUG(tiff_reader) << "bands: " << bands_ ;

    TIFFGetField(tif, TIFFTAG_IMAGEWIDTH, &width_);
    TIFFGetField(tif, TIFFTAG_IMAGELENGTH, &height_);

    TIFFGetField(tif, TIFFTAG_PLANARCONFIG, &planar_config_);
    TIFFGetField(tif, TIFFTAG_COMPRESSION, &compression_ );

    std::uint16_t orientation;
    if (TIFFGetField(tif, TIFFTAG_ORIENTATION, &orientation) == 0)
    {
        orientation = 1;
    }
    MAPNIK_LOG_DEBUG(tiff_reader) << "orientation: " << orientation ;
    MAPNIK_LOG_DEBUG(tiff_reader) << "planar-config: " << planar_config_ ;
    is_tiled_ = TIFFIsTiled(tif);

    if (is_tiled_)
    {
        TIFFGetField(tif, TIFFTAG_TILEWIDTH, &tile_width_);
        TIFFGetField(tif, TIFFTAG_TILELENGTH, &tile_height_);
        MAPNIK_LOG_DEBUG(tiff_reader) << "tiff is tiled";
        read_method_ = tiled;
    }
    else if (TIFFGetField(tif, TIFFTAG_ROWSPERSTRIP, &rows_per_strip_) != 0)
    {
        MAPNIK_LOG_DEBUG(tiff_reader) << "tiff is stripped";
        read_method_ = stripped;
    }
    //TIFFTAG_EXTRASAMPLES
    uint16 extrasamples = 0;
    uint16* sampleinfo = nullptr;
    if (TIFFGetField(tif, TIFFTAG_EXTRASAMPLES,
                     &extrasamples, &sampleinfo))
    {
        has_alpha_ = true;
        if (extrasamples > 0 &&
            sampleinfo[0] == EXTRASAMPLE_UNSPECIFIED)
        {
            throw image_reader_exception("Unspecified provided for extra samples to tiff reader.");
        }
    }
    // Try extracting bounding box from geoTIFF tags
    {
        uint16 count = 0;
        double *pixelscale;
        double *tilepoint;
        if (TIFFGetField(tif, 33550, &count, &pixelscale) == 1 && count == 3
            && TIFFGetField(tif, 33922 , &count,  &tilepoint) == 1 && count == 6)
        {
            MAPNIK_LOG_DEBUG(tiff_reader) << "PixelScale:" << pixelscale[0] << "," << pixelscale[1] << "," <<  pixelscale[2] ;
            MAPNIK_LOG_DEBUG(tiff_reader) << "TilePoint:" << tilepoint[0] << "," << tilepoint[1] << "," << tilepoint[2] ;
            MAPNIK_LOG_DEBUG(tiff_reader) << "          " << tilepoint[3] << "," << tilepoint[4] << "," << tilepoint[5] ;

            // assuming upper-left
            double lox = tilepoint[3];
            double loy = tilepoint[4];
            double hix = lox + pixelscale[0] * width_;
            double hiy = loy - pixelscale[1] * height_;
            bbox_.reset(box2d<double>(lox, loy, hix, hiy));
            MAPNIK_LOG_DEBUG(tiff_reader) << "Bounding Box:" << *bbox_ ;
        }

    }
    if (!is_tiled_ &&
        compression_ == COMPRESSION_NONE &&
        planar_config_ == PLANARCONFIG_CONTIG)
    {
        if (height_ > 128 * 1024 * 1024)
        {
            std::size_t line_size = (bands_ * width_ * bps_ + 7) / 8;
            std::size_t default_strip_height = 8192 / line_size;
            if (default_strip_height == 0) default_strip_height = 1;
            std::size_t num_strips = height_ / default_strip_height;
            if (num_strips > 128 * 1024 * 1024)
            {
                throw image_reader_exception("Can't allocate tiff");
            }
        }
    }
}

template <typename T>
tiff_reader<T>::~tiff_reader()
{
}

template <typename T>
unsigned tiff_reader<T>::width() const
{
    return width_;
}

template <typename T>
unsigned tiff_reader<T>::height() const
{
    return height_;
}

template <typename T>
boost::optional<box2d<double> > tiff_reader<T>::bounding_box() const
{
    return bbox_;
}

template <typename T>
void tiff_reader<T>::read(unsigned x,unsigned y,image_rgba8& image)
{
    if (read_method_==stripped)
    {
        read_stripped(static_cast<std::size_t>(x),static_cast<std::size_t>(y),image);
    }
    else if (read_method_==tiled)
    {
        read_tiled(static_cast<std::size_t>(x),static_cast<std::size_t>(y),image);
    }
    else
    {
        read_generic(static_cast<std::size_t>(x),static_cast<std::size_t>(y),image);
    }
}

template <typename T>
template <typename ImageData>
image_any tiff_reader<T>::read_any_gray(std::size_t x0, std::size_t y0, std::size_t width, std::size_t height)
{
    using image_type = ImageData;
    using pixel_type = typename image_type::pixel_type;
    if (read_method_ == tiled)
    {
        image_type data(width, height);
        read_tiled<image_type>(x0, y0, data);
        return image_any(std::move(data));
    }
    // TODO: temp disable and default to `scanline` method for stripped images.
    else if (read_method_ == stripped)
    {
        image_type data(width, height);
        read_stripped<image_type>(x0, y0, data);
        return image_any(std::move(data));
    }
    else
    {
        TIFF* tif = open(stream_);
        if (tif)
        {
            image_type data(width, height);
            std::size_t block_size = rows_per_strip_ > 0 ? rows_per_strip_ : tile_height_ ;
            std::size_t start_y = y0 - y0 % block_size;
            std::size_t end_y = std::min(y0 + height, height_);
            std::size_t start_x = x0;
            std::size_t end_x = std::min(x0 + width, width_);
            std::size_t element_size = sizeof(pixel_type);
            MAPNIK_LOG_DEBUG(tiff_reader) << "SCANLINE SIZE=" << TIFFScanlineSize(tif);
            std::size_t size_to_allocate = (TIFFScanlineSize(tif) + element_size - 1)/element_size;
            std::unique_ptr<pixel_type[]> const scanline(new pixel_type[size_to_allocate]);
            if (planar_config_ == PLANARCONFIG_CONTIG)
            {
                for  (std::size_t y = start_y; y < end_y; ++y)
                {
                    // we have to read all scanlines sequentially from start_y
                    // to be able to use scanline interface with compressed blocks.
                    if (-1 != TIFFReadScanline(tif, scanline.get(), y) && (y >= y0))
                    {
                        pixel_type * row = data.get_row(y - y0);
                        if (bands_ == 1)
                        {
                            std::transform(scanline.get() + start_x, scanline.get() + end_x, row, [](pixel_type const& p) { return p;});
                        }
                        else if (size_to_allocate == bands_ * width_)
                        {
                            // bands_ > 1 => packed bands in grayscale image e.g an extra alpha channel.
                            // Just pick first one for now.
                            pixel_type * buf = scanline.get() + start_x * bands_;
                            std::size_t x_index = 0;
                            for (std::size_t j = 0; j < end_x * bands_; ++j)
                            {
                                if (x_index >= width) break;
                                if (j % bands_ == 0)
                                {
                                    row[x_index++] = buf[j];
                                }
                            }
                        }
                    }
                }
            }
            else if (planar_config_ == PLANARCONFIG_SEPARATE)
            {
                for (std::size_t s = 0 ; s < bands_ ; ++s)
                {
                    for  (std::size_t y = start_y; y < end_y; ++y)
                    {
                        if (-1 != TIFFReadScanline(tif, scanline.get(), y) && (y >= y0))
                        {
                            pixel_type * row = data.get_row(y - y0);
                            std::transform(scanline.get() + start_x, scanline.get() + end_x, row, [](pixel_type const& p) { return p;});
                        }
                    }
                }
            }
            return image_any(std::move(data));
        }
    }
    return image_any();
}


namespace detail {

struct rgb8
{
    std::uint8_t r;
    std::uint8_t g;
    std::uint8_t b;
};

struct rgb8_to_rgba8
{
    std::uint32_t operator() (rgb8 const& in) const
    {
        return ((255 << 24) | (in.r) | (in.g << 8) | (in.b << 16));
    }
};

template <typename T>
struct tiff_reader_traits
{
    using image_type = T;
    using pixel_type = typename image_type::pixel_type;

    constexpr static bool reverse = false;
    static bool read_tile(TIFF * tif, std::size_t x, std::size_t y, pixel_type* buf, std::size_t tile_width, std::size_t tile_height)
    {
        std::uint32_t tile_size = TIFFTileSize(tif);
        return (TIFFReadEncodedTile(tif, TIFFComputeTile(tif, x, y, 0, 0), buf, tile_size) != -1);
    }

    static bool read_strip(TIFF * tif, std::size_t y, std::size_t rows_per_strip, std::size_t strip_width, pixel_type * buf)
    {
        return (TIFFReadEncodedStrip(tif, y/rows_per_strip, buf, -1) != -1);
    }
};

// default specialization that expands into RGBA
template <>
struct tiff_reader_traits<image_rgba8>
{
    using image_type = image_rgba8;
    using pixel_type = std::uint32_t;
    constexpr static bool reverse = true;
    static bool read_tile(TIFF * tif, std::size_t x0, std::size_t y0, pixel_type* buf, std::size_t tile_width, std::size_t tile_height)
    {
        return (TIFFReadRGBATile(tif, x0, y0, buf) != 0);
    }

    static bool read_strip(TIFF * tif, std::size_t y, std::size_t rows_per_strip, std::size_t strip_width, pixel_type * buf)
    {
        return (TIFFReadRGBAStrip(tif, y, buf) != 0);
    }
};

}

template <typename T>
image_any tiff_reader<T>::read(unsigned x, unsigned y, unsigned width, unsigned height)
{
    if (width > 10000 || height > 10000)
    {
        throw image_reader_exception("Can't allocate tiff > 10000x10000");
    }
    std::size_t x0 = static_cast<std::size_t>(x);
    std::size_t y0 = static_cast<std::size_t>(y);
    switch (photometric_)
    {
    case PHOTOMETRIC_MINISBLACK:
    case PHOTOMETRIC_MINISWHITE:
    {
        switch (bps_)
        {
        case 8:
        {
            switch (sample_format_)
            {
            case SAMPLEFORMAT_UINT:
            {
                return read_any_gray<image_gray8>(x0, y0, width, height);
            }
            case SAMPLEFORMAT_INT:
            {
                return read_any_gray<image_gray8s>(x0, y0, width, height);
            }
            default:
            {
                throw image_reader_exception("tiff_reader: This sample format is not supported for this bits per sample");
            }
            }
        }
        case 16:
        {
            switch (sample_format_)
            {
            case SAMPLEFORMAT_UINT:
            {
                return read_any_gray<image_gray16>(x0, y0, width, height);
            }
            case SAMPLEFORMAT_INT:
            {
                return read_any_gray<image_gray16s>(x0, y0, width, height);
            }
            default:
            {
                throw image_reader_exception("tiff_reader: This sample format is not supported for this bits per sample");
            }
            }
        }
        case 32:
        {
            switch (sample_format_)
            {
            case SAMPLEFORMAT_UINT:
            {
                return read_any_gray<image_gray32>(x0, y0, width, height);
            }
            case SAMPLEFORMAT_INT:
            {
                return read_any_gray<image_gray32s>(x0, y0, width, height);
            }
            case SAMPLEFORMAT_IEEEFP:
            {
                return read_any_gray<image_gray32f>(x0, y0, width, height);
            }
            default:
            {
                throw image_reader_exception("tiff_reader: This sample format is not supported for this bits per sample");
            }
            }
        }
        case 64:
        {
            switch (sample_format_)
            {
            case SAMPLEFORMAT_UINT:
            {
                return read_any_gray<image_gray64>(x0, y0, width, height);
            }
            case SAMPLEFORMAT_INT:
            {
                return read_any_gray<image_gray64s>(x0, y0, width, height);
            }
            case SAMPLEFORMAT_IEEEFP:
            {
                return read_any_gray<image_gray64f>(x0, y0, width, height);
            }
            default:
            {
                throw image_reader_exception("tiff_reader: This sample format is not supported for this bits per sample");
            }
            }
        }
        }
    }
    default:
    {
        //PHOTOMETRIC_PALETTE = 3;
        //PHOTOMETRIC_MASK = 4;
        //PHOTOMETRIC_SEPARATED = 5;
        //PHOTOMETRIC_YCBCR = 6;
        //PHOTOMETRIC_CIELAB = 8;
        //PHOTOMETRIC_ICCLAB = 9;
        //PHOTOMETRIC_ITULAB = 10;
        //PHOTOMETRIC_LOGL = 32844;
        //PHOTOMETRIC_LOGLUV = 32845;
        image_rgba8 data(width,height, true, true);
        read(x0, y0, data);
        return image_any(std::move(data));
    }
    }
    return image_any();
}

template <typename T>
template <typename ImageData>
void tiff_reader<T>::read_generic(std::size_t, std::size_t, ImageData &)
{
    throw image_reader_exception("tiff_reader: TODO - tiff is not stripped or tiled");
}

template <typename T>
template <typename ImageData>
void tiff_reader<T>::read_tiled(std::size_t x0,std::size_t y0, ImageData & image)
{
    using pixel_type = typename detail::tiff_reader_traits<ImageData>::pixel_type;

    TIFF* tif = open(stream_);
    if (tif)
    {
        std::uint32_t tile_size = TIFFTileSize(tif);
        std::unique_ptr<pixel_type[]> tile(new pixel_type[tile_size]);
        std::size_t width = image.width();
        std::size_t height = image.height();
        std::size_t start_y = (y0 / tile_height_) * tile_height_;
        std::size_t end_y = ((y0 + height) / tile_height_ + 1) * tile_height_;
        std::size_t start_x = (x0 / tile_width_) * tile_width_;
        std::size_t end_x = ((x0 + width) / tile_width_ + 1) * tile_width_;
        end_y = std::min(end_y, height_);
        end_x = std::min(end_x, width_);
        bool pick_first_band = (bands_ > 1) && (tile_size / (tile_width_ * tile_height_ * sizeof(pixel_type)) == bands_);
        for (std::size_t y = start_y; y < end_y; y += tile_height_)
        {
            std::size_t ty0 = std::max(y0, y) - y;
            std::size_t ty1 = std::min(height + y0, y + tile_height_) - y;

            for (std::size_t x = start_x; x < end_x; x += tile_width_)
            {
                if (!detail::tiff_reader_traits<ImageData>::read_tile(tif, x, y, tile.get(), tile_width_, tile_height_))
                {
                    MAPNIK_LOG_DEBUG(tiff_reader) <<  "read_tile(...) failed at " << x << "/" << y << " for " << width_ << "/" << height_ << "\n";
                    break;
                }
                if (pick_first_band)
                {
                    std::uint32_t size = tile_width_ * tile_height_ * sizeof(pixel_type);
                    for (std::uint32_t n = 0; n < size; ++n)
                    {
                        tile[n] = tile[n * bands_];
                    }
                }
                std::size_t tx0 = std::max(x0, x);
                std::size_t tx1 = std::min(width + x0, x + tile_width_);
                std::size_t row_index = y + ty0 - y0;

                if (detail::tiff_reader_traits<ImageData>::reverse)
                {
                    for (std::size_t ty = ty0; ty < ty1; ++ty, ++row_index)
                    {
                        // This is in reverse because the TIFFReadRGBATile reads are inverted
                        image.set_row(row_index, tx0 - x0, tx1 - x0, &tile[(tile_height_ - ty - 1) * tile_width_ + tx0 - x]);
                    }
                }
                else
                {
                    for (std::size_t ty = ty0; ty < ty1; ++ty, ++row_index)
                    {
                        image.set_row(row_index, tx0 - x0, tx1 - x0, &tile[ty * tile_width_ + tx0 - x]);
                    }
                }
            }
        }
    }
}

template <typename T>
template <typename ImageData>
void tiff_reader<T>::read_stripped(std::size_t x0, std::size_t y0, ImageData & image)
{
    using pixel_type = typename detail::tiff_reader_traits<ImageData>::pixel_type;
    TIFF* tif = open(stream_);
    if (tif)
    {
        std::uint32_t strip_size = TIFFStripSize(tif);
        std::unique_ptr<pixel_type[]> strip(new pixel_type[strip_size]);
        std::size_t width = image.width();
        std::size_t height = image.height();

        std::size_t start_y = (y0 / rows_per_strip_) * rows_per_strip_;
        std::size_t end_y = std::min(y0 + height, height_);
        std::size_t tx0, tx1, ty0, ty1;

        tx0 = x0;
        tx1 = std::min(width + x0, width_);
        std::size_t row = 0;
        bool pick_first_band = (bands_ > 1) && (strip_size / (width_ * rows_per_strip_ * sizeof(pixel_type)) == bands_);
        for (std::size_t y = start_y; y < end_y; y += rows_per_strip_)
        {
            ty0 = std::max(y0, y) - y;
            ty1 = std::min(end_y, y + rows_per_strip_) - y;

            if (!detail::tiff_reader_traits<ImageData>::read_strip(tif, y, rows_per_strip_, width_, strip.get()))
            {
                MAPNIK_LOG_DEBUG(tiff_reader) << "TIFFRead(Encoded|RGBA)Strip failed at " << y << " for " << width_ << "/" << height_ << "\n";
                break;
            }
            if (pick_first_band)
            {
                std::uint32_t size = width_ * rows_per_strip_ * sizeof(pixel_type);
                for (std::uint32_t n = 0; n < size; ++n)
                {
                    strip[n] = strip[bands_ * n];
                }
            }

            if (detail::tiff_reader_traits<ImageData>::reverse)
            {
                std::size_t num_rows = std::min(end_y - y, static_cast<std::size_t>(rows_per_strip_));
                for (std::size_t ty = ty0; ty < ty1; ++ty)
                {
                    // This is in reverse because the TIFFReadRGBAStrip reads are inverted
                    image.set_row(row++, tx0 - x0, tx1 - x0, &strip[(num_rows - ty - 1) * width_ + tx0]);
                }
            }
            else
            {
                for (std::size_t ty = ty0; ty < ty1; ++ty)
                {
                    image.set_row(row++, tx0 - x0, tx1 - x0, &strip[ty * width_ + tx0]);
                }
            }
        }
    }
}

template <typename T>
TIFF* tiff_reader<T>::open(std::istream & input)
{
    if (!tif_)
    {
        tif_ = tiff_ptr(TIFFClientOpen("tiff_input_stream", "rcm",
                                       reinterpret_cast<thandle_t>(&input),
                                       impl::tiff_read_proc,
                                       impl::tiff_write_proc,
                                       impl::tiff_seek_proc,
                                       impl::tiff_close_proc,
                                       impl::tiff_size_proc,
                                       impl::tiff_map_proc,
                                       impl::tiff_unmap_proc), tiff_closer());
    }
    return tif_.get();
}

} // namespace mapnik