/* SPDX-FileCopyrightText: 2001-2002 NaN Holding BV. All rights reserved.
 * SPDX-FileCopyrightText: 2024 Blender Authors
 *
 * SPDX-License-Identifier: GPL-2.0-or-later */

/** \file
 * \ingroup imbuf
 */

#include "BLI_array.hh"
#include "BLI_rect.h"
#include "BLI_task.hh"

#include "IMB_filter.hh"
#include "IMB_imbuf.hh"
#include "IMB_imbuf_types.hh"

#include "IMB_colormanagement.hh"

#include "MEM_guardedalloc.h"

#include "OCIO_colorspace.hh"

namespace blender {

/* -------------------------------------------------------------------- */

/** \name Generic Buffer Conversion
 * \{ */

MINLINE uchar ftochar(float value)
{
  return unit_float_to_uchar_clamp(value);
}

MINLINE void float_to_byte_dither_v4(uchar b[4], const float f[4], float dither, int x, int y)
{
  float dither_value = dither_random_value(x, y) * 0.0033f * dither;

  b[0] = ftochar(dither_value + f[0]);
  b[1] = ftochar(dither_value + f[1]);
  b[2] = ftochar(dither_value + f[2]);
  b[3] = unit_float_to_uchar_clamp(f[3]);
}

bool IMB_alpha_affects_rgb(const ImBuf *ibuf)
{
  return ibuf && !flag_is_set(ibuf->flags, ImBufFlags::AlphaChannelPacked);
}

void IMB_buffer_byte_from_float(uchar *dest,
                                const float *src,
                                int src_channels,
                                float dither,
                                bool predivide,
                                int width,
                                int height,
                                int stride,
                                int start_y)
{
  for (int y = 0; y < height; y++) {
    const float *from = src + size_t(stride) * y * src_channels;
    uchar *to = dest + size_t(stride) * y * 4;
    if (src_channels == 1) {
      /* single channel input */
      for (int x = 0; x < width; x++, from++, to += 4) {
        to[0] = to[1] = to[2] = to[3] = unit_float_to_uchar_clamp(from[0]);
      }
    }
    else if (src_channels == 3) {
      /* RGB input */
      for (int x = 0; x < width; x++, from += 3, to += 4) {
        rgb_float_to_uchar(to, from);
        to[3] = 255;
      }
    }
    else if (src_channels == 4) {
      /* RGBA input */
      if (dither && predivide) {
        float straight[4];
        for (int x = 0; x < width; x++, from += 4, to += 4) {
          premul_to_straight_v4_v4(straight, from);
          float_to_byte_dither_v4(to, straight, dither, x, y + start_y);
        }
      }
      else if (dither) {
        for (int x = 0; x < width; x++, from += 4, to += 4) {
          float_to_byte_dither_v4(to, from, dither, x, y + start_y);
        }
      }
      else if (predivide) {
        for (int x = 0; x < width; x++, from += 4, to += 4) {
          premul_float_to_straight_uchar(to, from);
        }
      }
      else {
        for (int x = 0; x < width; x++, from += 4, to += 4) {
          rgba_float_to_uchar(to, from);
        }
      }
    }
  }
}

void IMB_buffer_byte_from_float_mask(uchar *dest,
                                     const float *src,
                                     int src_channels,
                                     float dither,
                                     int width,
                                     int height,
                                     const char *mask)
{
  for (int y = 0; y < height; y++) {
    const float *from = src + size_t(width) * y * src_channels;
    uchar *to = dest + size_t(width) * y * 4;
    if (src_channels == 1) {
      /* single channel input */
      for (int x = 0; x < width; x++, from++, to += 4) {
        if (*mask++ == FILTER_MASK_USED) {
          to[0] = to[1] = to[2] = to[3] = unit_float_to_uchar_clamp(from[0]);
        }
      }
    }
    else if (src_channels == 3) {
      /* RGB input */
      for (int x = 0; x < width; x++, from += 3, to += 4) {
        if (*mask++ == FILTER_MASK_USED) {
          rgb_float_to_uchar(to, from);
          to[3] = 255;
        }
      }
    }
    else if (src_channels == 4) {
      /* RGBA input */
      if (dither) {
        for (int x = 0; x < width; x++, from += 4, to += 4) {
          if (*mask++ == FILTER_MASK_USED) {
            float_to_byte_dither_v4(to, from, dither, x, y);
          }
        }
      }
      else {
        for (int x = 0; x < width; x++, from += 4, to += 4) {
          if (*mask++ == FILTER_MASK_USED) {
            rgba_float_to_uchar(to, from);
          }
        }
      }
    }
  }
}

void IMB_buffer_float_from_byte(
    float *dest, const uchar *src, int width, int height, int dest_stride, int src_stride)
{
  for (int y = 0; y < height; y++) {
    const uchar *from = src + size_t(src_stride) * y * 4;
    float *to = dest + size_t(dest_stride) * y * 4;

    for (int x = 0; x < width; x++, from += 4, to += 4) {
      rgba_uchar_to_float(to, from);
    }
  }
}

void IMB_buffer_float_rgba_from_float(
    float *dest, const float *src, int src_channels, int width, int height)
{
  if (src_channels == 1) {
    /* single channel input */
    for (int y = 0; y < height; y++) {
      const float *from = src + size_t(width) * y;
      float *to = dest + size_t(width) * y * 4;

      for (int x = 0; x < width; x++, from++, to += 4) {
        to[0] = to[1] = to[2] = to[3] = from[0];
      }
    }
  }
  else if (src_channels == 3) {
    /* RGB input */
    for (int y = 0; y < height; y++) {
      const float *from = src + size_t(width) * y * 3;
      float *to = dest + size_t(width) * y * 4;

      for (int x = 0; x < width; x++, from += 3, to += 4) {
        copy_v3_v3(to, from);
        to[3] = 1.0f;
      }
    }
  }
  else if (src_channels == 4) {
    /* RGBA input */
    for (int y = 0; y < height; y++) {
      const float *from = src + size_t(width) * y * 4;
      float *to = dest + size_t(width) * y * 4;
      memcpy(to, from, sizeof(float) * size_t(4) * width);
    }
  }
}

void IMB_buffer_float_rgba_from_float_mask(
    float *dest, const float *src, int src_channels, int width, int height, const char *mask)
{
  if (src_channels == 1) {
    /* single channel input */
    for (int y = 0; y < height; y++) {
      const float *from = src + size_t(width) * y;
      float *to = dest + size_t(width) * y * 4;

      for (int x = 0; x < width; x++, from++, to += 4) {
        if (*mask++ == FILTER_MASK_USED) {
          to[0] = to[1] = to[2] = to[3] = from[0];
        }
      }
    }
  }
  else if (src_channels == 3) {
    /* RGB input */
    for (int y = 0; y < height; y++) {
      const float *from = src + size_t(width) * y * 3;
      float *to = dest + size_t(width) * y * 4;

      for (int x = 0; x < width; x++, from += 3, to += 4) {
        if (*mask++ == FILTER_MASK_USED) {
          copy_v3_v3(to, from);
          to[3] = 1.0f;
        }
      }
    }
  }
  else if (src_channels == 4) {
    /* RGBA input */
    for (int y = 0; y < height; y++) {
      const float *from = src + size_t(width) * y * 4;
      float *to = dest + size_t(width) * y * 4;

      for (int x = 0; x < width; x++, from += 4, to += 4) {
        if (*mask++ == FILTER_MASK_USED) {
          copy_v4_v4(to, from);
        }
      }
    }
  }
}

void IMB_buffer_float_rgba_srgb_to_linear(float *buffer, int width, int height)
{
  threading::parallel_for(IndexRange(height), 64, [&](const IndexRange y_range) {
    for (int y : y_range) {
      float *ptr = buffer + size_t(width) * y * 4;
      for (int x = 0; x < width; x++, ptr += 4) {
        srgb_to_linearrgb_predivide_v4(ptr, ptr);
      }
    }
  });
}

/** \} */

/* -------------------------------------------------------------------- */
/** \name ImBuf Conversion
 * \{ */

void IMB_byte_from_float(ImBuf *ibuf)
{
  /* Nothing to do if there's no float buffer */
  const float *float_data = ibuf->float_data();
  if (float_data == nullptr) {
    return;
  }

  /* Allocate byte buffer if needed. */
  if (ibuf->byte_data() == nullptr) {
    if (!IMB_alloc_byte_pixels(ibuf, false)) {
      return;
    }
  }

  const char *from_colorspace = IMB_colormanagement_get_float_colorspace(ibuf);
  const char *to_colorspace = IMB_colormanagement_get_byte_colorspace(ibuf);
  const bool predivide = IMB_alpha_affects_rgb(ibuf);
  ColormanageProcessor processor = ColormanageProcessor::colorspace_processor_new(from_colorspace,
                                                                                  to_colorspace);

  /* At 4 floats per pixel, this is 32KB of data, and fits into typical CPU L1 cache. */
  static constexpr int grain_size = 2048;
  uchar *byte_data = ibuf->byte_data_for_write();
  threading::parallel_for(
      IndexRange(IMB_get_pixel_count(ibuf)), grain_size, [&](const IndexRange range) {
        /* Copy chunk of source float pixels into a local buffer. */
        Array<float, grain_size * 4> buffer(range.size() * ibuf->channels);
        buffer.as_mutable_span().copy_from(
            Span(float_data + range.first() * ibuf->channels, buffer.size()));
        /* Unpremultiply alpha if needed. */
        if (predivide) {
          IMB_unpremultiply_rect_float(buffer.data(), ibuf->channels, range.size(), 1);
        }
        /* Convert to byte color space if needed. */
        if (!processor.is_noop()) {
          processor.apply(buffer.data(), range.size(), 1, ibuf->channels, false);
        }
        /* Convert to bytes. */
        IMB_buffer_byte_from_float(byte_data + range.first() * 4,
                                   buffer.data(),
                                   ibuf->channels,
                                   ibuf->dither,
                                   false,
                                   range.size(),
                                   1,
                                   ibuf->x);
      });

  /* ensure user flag is reset */
  ibuf->userflags &= ~IB_RECT_INVALID;
}

void IMB_float_from_byte_ex(ImBuf *dst, const ImBuf *src, const rcti *region_to_update)
{
  BLI_assert_msg(dst->float_data() != nullptr,
                 "Destination buffer should have a float buffer assigned.");
  BLI_assert_msg(src->byte_data() != nullptr, "Source buffer should have a byte buffer assigned.");
  BLI_assert_msg(dst->x == src->x, "Source and destination buffer should have the same dimension");
  BLI_assert_msg(dst->y == src->y, "Source and destination buffer should have the same dimension");
  BLI_assert_msg(dst->channels = 4, "Destination buffer should have 4 channels.");
  BLI_assert_msg(region_to_update->xmin >= 0,
                 "Region to update should be clipped to the given buffers.");
  BLI_assert_msg(region_to_update->ymin >= 0,
                 "Region to update should be clipped to the given buffers.");
  BLI_assert_msg(region_to_update->xmax <= dst->x,
                 "Region to update should be clipped to the given buffers.");
  BLI_assert_msg(region_to_update->ymax <= dst->y,
                 "Region to update should be clipped to the given buffers.");

  const int region_width = BLI_rcti_size_x(region_to_update);
  const int region_height = BLI_rcti_size_y(region_to_update);
  const bool premultiply_alpha = IMB_alpha_affects_rgb(src);

  const uchar *byte_data = src->byte_data();
  float *float_data = dst->float_data_for_write();
  threading::parallel_for(
      IndexRange(region_to_update->ymin, region_height), 64, [&](const IndexRange y_range) {
        const uchar *src_ptr = byte_data + (region_to_update->xmin + y_range.first() * dst->x) * 4;
        float *dst_ptr = float_data + (region_to_update->xmin + y_range.first() * dst->x) * 4;

        /* Convert byte -> float without color or alpha conversions. */
        IMB_buffer_float_from_byte(dst_ptr, src_ptr, region_width, y_range.size(), src->x, dst->x);

        /* Convert to scene linear color space, and premultiply alpha if needed. */
        float *dst_ptr_line = dst_ptr;
        for ([[maybe_unused]] const int64_t y : y_range) {
          IMB_colormanagement_colorspace_to_scene_linear(
              dst_ptr_line, region_width, 1, dst->channels, src->byte_buffer.colorspace, false);
          if (premultiply_alpha) {
            IMB_premultiply_rect_float(dst_ptr_line, dst->channels, region_width, 1);
          }
          dst_ptr_line += 4 * dst->x;
        }
      });
}

void IMB_float_from_byte(ImBuf *ibuf)
{
  /* Nothing to do if there's no byte buffer. */
  if (ibuf->byte_data() == nullptr) {
    return;
  }

  /* Allocate float buffer if needed. */
  if (ibuf->float_data() == nullptr) {
    if (!IMB_alloc_float_pixels(ibuf, 4, false)) {
      return;
    }
  }

  rcti region_to_update;
  BLI_rcti_init(&region_to_update, 0, ibuf->x, 0, ibuf->y);
  IMB_float_from_byte_ex(ibuf, ibuf, &region_to_update);
}

/** \} */

/* -------------------------------------------------------------------- */
/** \name Color to Gray-Scale
 * \{ */

void IMB_color_to_bw(ImBuf *ibuf)
{
  float *rct_fl = ibuf->float_data_for_write();
  uchar *rct = ibuf->byte_data_for_write();
  size_t i;

  if (rct_fl) {
    if (ibuf->channels >= 3) {
      for (i = IMB_get_pixel_count(ibuf); i > 0; i--, rct_fl += ibuf->channels) {
        rct_fl[0] = rct_fl[1] = rct_fl[2] = IMB_colormanagement_get_luminance(rct_fl);
      }
    }
  }

  if (rct) {
    for (i = IMB_get_pixel_count(ibuf); i > 0; i--, rct += 4) {
      rct[0] = rct[1] = rct[2] = IMB_colormanagement_get_luminance_byte(rct);
    }
  }
}

/** \} */

/* -------------------------------------------------------------------- */
/** \name Alter Saturation
 * \{ */

void IMB_saturation(ImBuf *ibuf, float sat)
{
  const size_t pixel_count = IMB_get_pixel_count(ibuf);
  if (uchar *byte_data = ibuf->byte_data_for_write()) {
    threading::parallel_for(IndexRange(pixel_count), 64 * 1024, [&](IndexRange range) {
      uchar *ptr = byte_data + range.first() * 4;
      float rgb[3];
      float hsv[3];
      for ([[maybe_unused]] const int64_t i : range) {
        rgb_uchar_to_float(rgb, ptr);
        rgb_to_hsv_v(rgb, hsv);
        hsv_to_rgb(hsv[0], hsv[1] * sat, hsv[2], rgb + 0, rgb + 1, rgb + 2);
        rgb_float_to_uchar(ptr, rgb);
        ptr += 4;
      }
    });
  }

  float *float_data = ibuf->float_data_for_write();
  if (float_data != nullptr && ibuf->channels >= 3) {
    threading::parallel_for(IndexRange(pixel_count), 64 * 1024, [&](IndexRange range) {
      const int channels = ibuf->channels;
      float *ptr = float_data + range.first() * channels;
      float hsv[3];
      for ([[maybe_unused]] const int64_t i : range) {
        rgb_to_hsv_v(ptr, hsv);
        hsv_to_rgb(hsv[0], hsv[1] * sat, hsv[2], ptr + 0, ptr + 1, ptr + 2);
        ptr += channels;
      }
    });
  }
}

/** \} */

}  // namespace blender