/* Turn uhdr (RGB plus a gainmap) to scRGB colourspace.

 *

 * 26/11/25

 *  - from XYZ2scRGB.c.c

 */

/*

  This file is part of VIPS.

  VIPS 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 of the License, or

  (at your option) any later version.

  This program 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 program; if not, write to the Free Software

  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA

  02110-1301  USA

 */

/*

  These files are distributed with VIPS - http://www.vips.ecs.soton.ac.uk

 */

#ifdef HAVE_CONFIG_H

#include <config.h>

#endif /*HAVE_CONFIG_H*/

#include <glib/gi18n-lib.h>

#include <stdio.h>

#include <math.h>

#include <vips/vips.h>

#include "pcolour.h"

typedef struct _VipsUhdr2scRGB {

  VipsColour parent;

  VipsImage *in;

  /* Gainmap metadata.

   */

  float gamma[3];

  float min_content_boost[3];

  float max_content_boost[3];

  float offset_hdr[3];

  float offset_sdr[3];

  /* And the actual map.

   */

  VipsImage *gainmap;

} VipsUhdr2scRGB;

typedef VipsColourClass VipsUhdr2scRGBClass;

G_DEFINE_TYPE(VipsUhdr2scRGB, vips_uhdr2scRGB, VIPS_TYPE_COLOUR);

/* Derived from the apache-licensed applyGain() method of libuhdr.

 */

/* Monochrome gainmap, colour image. Probably the most common case.

 */

static void

vips_uhdr2scRGB_mono(VipsUhdr2scRGB *uhdr,

  VipsPel *out, VipsPel **in, int width)

{

  VipsPel *restrict p1 = in[0];

  VipsPel *restrict p2 = in[1];

  float *restrict q = (float *) out;

  for (int i = 0; i < width; i++) {

    float r = vips_v2Y_8[p1[0]];

    float g = vips_v2Y_8[p1[1]];

    float b = vips_v2Y_8[p1[2]];

    p1 += 3;

    // the gainmap is not gamma corrected in libultrahdr, confusingly

    float gg = p2[0] / 255.0;

    p2 += 1;

    if (uhdr->gamma[1] != 1.0f)

      gg = pow(gg, 1.0f / uhdr->gamma[1]);

    float boostg = log2(uhdr->min_content_boost[1]) * (1.0f - gg) +

      log2(uhdr->max_content_boost[1]) * gg;

    float gaing = exp2(boostg);

    q[0] = ((r + uhdr->offset_sdr[1]) * gaing) - uhdr->offset_hdr[1];

    q[1] = ((g + uhdr->offset_sdr[1]) * gaing) - uhdr->offset_hdr[1];

    q[2] = ((b + uhdr->offset_sdr[1]) * gaing) - uhdr->offset_hdr[1];

    q += 3;

  }

}

/* Colour image, colour gainmap. Allowed, but not common.

 */

static void

vips_uhdr2scRGB_rgb(VipsUhdr2scRGB *uhdr, VipsPel *out, VipsPel **in, int width)

{

  VipsPel *restrict p1 = in[0];

  VipsPel *restrict p2 = in[1];

  float *restrict q = (float *) out;

  for (int i = 0; i < width; i++) {

    float r = vips_v2Y_8[p1[0]];

    float g = vips_v2Y_8[p1[1]];

    float b = vips_v2Y_8[p1[2]];

    p1 += 3;

    float gr = vips_v2Y_8[p2[0]];

    float gg = vips_v2Y_8[p2[1]];

    float gb = vips_v2Y_8[p2[2]];

    p2 += 3;

    if (uhdr->gamma[0] != 1.0f)

      gr = pow(gr, 1.0f / uhdr->gamma[0]);

    if (uhdr->gamma[1] != 1.0f)

      gg = pow(gg, 1.0f / uhdr->gamma[1]);

    if (uhdr->gamma[2] != 1.0f)

      gb = pow(gb, 1.0f / uhdr->gamma[2]);

    float boostr = log2(uhdr->min_content_boost[0]) * (1.0f - gr) +

      log2(uhdr->max_content_boost[0]) * gr;

    float boostg = log2(uhdr->min_content_boost[1]) * (1.0f - gg) +

      log2(uhdr->max_content_boost[1]) * gg;

    float boostb = log2(uhdr->min_content_boost[2]) * (1.0f - gb) +

      log2(uhdr->max_content_boost[2]) * gb;

    float gainr = exp2(boostr);

    float gaing = exp2(boostg);

    float gainb = exp2(boostb);

    q[0] = ((r + uhdr->offset_sdr[0]) * gainr) - uhdr->offset_hdr[0];

    q[1] = ((g + uhdr->offset_sdr[1]) * gaing) - uhdr->offset_hdr[1];

    q[2] = ((b + uhdr->offset_sdr[2]) * gainb) - uhdr->offset_hdr[2];

    q += 3;

  }

}

static void

vips_uhdr2scRGB_line(VipsColour *colour, VipsPel *out, VipsPel **in, int width)

{

  VipsUhdr2scRGB *uhdr = (VipsUhdr2scRGB *) colour;

  g_assert(colour->in[0]->Xsize == colour->in[1]->Xsize);

  g_assert(colour->in[0]->Ysize == colour->in[1]->Ysize);

  if (uhdr->gainmap->Bands == 1)

    vips_uhdr2scRGB_mono(uhdr, out, in, width);

  else

    vips_uhdr2scRGB_rgb(uhdr, out, in, width);

}

// pass in the array to fill, size must match

static int

image_get_array_float(VipsImage *image, const char *name,

  float *out, int n_out)

{

  double *d;

  int n;

  if (vips_image_get_array_double(image, name, &d, &n))

    return -1;

  if (n != n_out) {

    vips_error("image_get_array_float", _("bad size"));

    return -1;

  }

  for (int i = 0; i < n; i++)

    out[i] = d[i];

  return 0;

}

static int

vips_uhdr2scRGB_build(VipsObject *object)

{

  VipsObjectClass *class = VIPS_OBJECT_GET_CLASS(object);

  VipsColour *colour = VIPS_COLOUR(object);

  VipsUhdr2scRGB *uhdr = (VipsUhdr2scRGB *) object;

  /* We allow one-band gainmap plus 3 band main image, so we have to turn

   * off the automatic detach-attach alpha processing.

   */

  colour->input_bands = 0;

  colour->n = 2;

  colour->in = (VipsImage **) vips_object_local_array(object, 2);

  /* Get the gainmap image metadata.

   */

  if (uhdr->in) {

    if (vips_check_bands(class->nickname, uhdr->in, 3))

      return -1;

    if (uhdr->in->BandFmt != VIPS_FORMAT_UCHAR) {

      vips_error(class->nickname, "%s", _("image must be uchar"));

      return -1;

    }

    /* Need this for fast srgb -> scRGB.

     */

    vips_col_make_tables_RGB_8();

    if (image_get_array_float(uhdr->in,

        "gainmap-max-content-boost", &uhdr->max_content_boost[0], 3) ||

      image_get_array_float(uhdr->in,

        "gainmap-min-content-boost", &uhdr->min_content_boost[0], 3) ||

      image_get_array_float(uhdr->in,

        "gainmap-gamma", &uhdr->gamma[0], 3) ||

      image_get_array_float(uhdr->in,

        "gainmap-offset-sdr", &uhdr->offset_sdr[0], 3) ||

      image_get_array_float(uhdr->in,

        "gainmap-offset-hdr", &uhdr->offset_hdr[0], 3))

      return -1;

    VipsImage *gainmap;

    if (!(gainmap = vips_image_get_gainmap(uhdr->in)))

      return -1;

    if (vips_check_bands_1or3(class->nickname, gainmap))

      return -1;

    /* Scale the gainmap image to match the main image 1:1.

     */

    if (vips_resize(gainmap, &uhdr->gainmap,

        (double) uhdr->in->Xsize / gainmap->Xsize,

        "vscale", (double) uhdr->in->Ysize / gainmap->Ysize,

        "kernel", VIPS_KERNEL_LINEAR,

        NULL))

      return -1;

    g_object_unref(gainmap);

    colour->in[0] = uhdr->in;

    g_object_ref(uhdr->in);

    colour->in[1] = uhdr->gainmap;

  }

  if (VIPS_OBJECT_CLASS(vips_uhdr2scRGB_parent_class)->build(object))

    return -1;

  return 0;

}

static void

vips_uhdr2scRGB_class_init(VipsUhdr2scRGBClass *class)

{

  GObjectClass *gobject_class = G_OBJECT_CLASS(class);

  VipsObjectClass *object_class = (VipsObjectClass *) class;

  VipsColourClass *colour_class = VIPS_COLOUR_CLASS(class);

  gobject_class->set_property = vips_object_set_property;

  gobject_class->get_property = vips_object_get_property;

  object_class->nickname = "uhdr2scRGB";

  object_class->description = _("transform uhdr to scRGB");

  object_class->build = vips_uhdr2scRGB_build;

  colour_class->process_line = vips_uhdr2scRGB_line;

  VIPS_ARG_IMAGE(class, "in", 1,

    _("Input"),

    _("Input image"),

    VIPS_ARGUMENT_REQUIRED_INPUT,

    G_STRUCT_OFFSET(VipsColourTransform, in));

}

static void

vips_uhdr2scRGB_init(VipsUhdr2scRGB *uhdr)

{

  VipsColour *colour = VIPS_COLOUR(uhdr);

  colour->interpretation = VIPS_INTERPRETATION_scRGB;

  colour->format = VIPS_FORMAT_FLOAT;

  colour->bands = 3;

}

/**

 * vips_uhdr2scRGB: (method)

 * @in: input image

 * @out: (out): output image

 * @...: `NULL`-terminated list of optional named arguments

 *

 * Transform a uhdr image (three band sRGB with an attached gainmap) to

 * scRGB.

 *

 * Returns: 0 on success, -1 on error

 */

int

vips_uhdr2scRGB(VipsImage *in, VipsImage **out, ...)

{

  va_list ap;

  int result;

  va_start(ap, out);

  result = vips_call_split("uhdr2scRGB", ap, in, out);

  va_end(ap);

  return result;

}