// Copyright 2022 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "gpu/command_buffer/service/shared_image/gl_repack_utils.h"

#include <vector>

#include "base/bits.h"
#include "base/check_op.h"
#include "base/containers/span.h"
#include "gpu/command_buffer/service/shared_image/copy_image_plane.h"
#include "third_party/skia/include/core/SkPixmap.h"
#include "ui/gfx/skia_span_util.h"

namespace gpu {

std::vector<uint8_t> RepackPixelDataAsRgb(const gfx::Size& size,
                                          const SkPixmap& src_pixmap,
                                          bool src_is_bgrx) {
  DCHECK_EQ(src_pixmap.info().bytesPerPixel(), 4);

  constexpr size_t kSrcBytesPerPixel = 4;
  constexpr size_t kDstBytesPerPixel = 3;

  base::span<const uint8_t> src_data = gfx::SkPixmapToSpan(src_pixmap);
  size_t src_stride = src_pixmap.rowBytes();

  // 3 bytes per pixel with 4 byte row alignment.
  size_t dst_stride =
      base::bits::AlignUp<size_t>(size.width() * kDstBytesPerPixel, 4);
  std::vector<uint8_t> dst_data(dst_stride * size.height());
  base::span<uint8_t> dst_span(dst_data);

  const size_t src_payload_bytes = size.width() * kSrcBytesPerPixel;
  const size_t dst_payload_bytes = size.width() * kDstBytesPerPixel;

  for (int y = 0; y < size.height(); ++y) {
    base::span<const uint8_t> src_row =
        src_data.subspan(y * src_stride, src_payload_bytes);
    base::span<uint8_t> dst_row =
        dst_span.subspan(y * dst_stride, dst_payload_bytes);
    for (int x = 0; x < size.width(); ++x) {
      base::span<const uint8_t, kSrcBytesPerPixel> src =
          src_row.take_first<kSrcBytesPerPixel>();
      base::span<uint8_t, kDstBytesPerPixel> dst =
          dst_row.take_first<kDstBytesPerPixel>();
      if (src_is_bgrx) {
        dst[0] = src[2];
        dst[1] = src[1];
        dst[2] = src[0];
      } else {
        dst[0] = src[0];
        dst[1] = src[1];
        dst[2] = src[2];
      }
    }
  }

  return dst_data;
}

std::vector<uint8_t> RepackPixelDataWithStride(const gfx::Size& size,
                                               const SkPixmap& src_pixmap,
                                               size_t dst_stride) {
  size_t src_stride = src_pixmap.rowBytes();
  DCHECK_LT(dst_stride, src_stride);

  std::vector<uint8_t> dst_data(dst_stride * size.height());
  CopyImagePlane(gfx::SkPixmapToSpan(src_pixmap), src_stride, dst_data,
                 dst_stride, src_pixmap.info().minRowBytes(), size.height());

  return dst_data;
}

void UnpackPixelDataWithStride(const gfx::Size& size,
                               const std::vector<uint8_t>& src_data,
                               size_t src_stride,
                               const SkPixmap& dst_pixmap) {
  size_t dst_stride = dst_pixmap.rowBytes();

  DCHECK_GT(dst_stride, src_stride);

  CopyImagePlane(src_data, src_stride, gfx::SkPixmapToWritableSpan(dst_pixmap),
                 dst_stride, dst_pixmap.info().minRowBytes(), size.height());
}

void SwizzleRedAndBlue(const SkPixmap& pixmap) {
  DCHECK_EQ(pixmap.info().bytesPerPixel(), 4);

  base::span<uint8_t> data = gfx::SkPixmapToWritableSpan(pixmap);
  size_t stride = pixmap.rowBytes();

  for (int y = 0; y < pixmap.height(); ++y) {
    size_t row_offset = y * stride;
    for (int x = 0; x < pixmap.width(); ++x) {
      size_t pixel_offset = row_offset + x * 4;
      std::swap(data[pixel_offset], data[pixel_offset + 2]);
    }
  }
}

}  // namespace gpu