// Copyright (c) the JPEG XL Project Authors. All rights reserved.

//

// Use of this source code is governed by a BSD-style

// license that can be found in the LICENSE file.

#include "lib/jxl/image_ops.h"

#include <cstddef>

#include <cstring>

#include "lib/jxl/base/common.h"

#include "lib/jxl/base/compiler_specific.h"

#include "lib/jxl/base/status.h"

#include "lib/jxl/frame_dimensions.h"

#include "lib/jxl/image.h"

namespace jxl {

Status PadImageToBlockMultipleInPlace(Image3F* JXL_RESTRICT in,

                                      size_t block_dim) {

  const size_t xsize_orig = in->xsize();

  const size_t ysize_orig = in->ysize();

  const size_t xsize = RoundUpTo(xsize_orig, block_dim);

  const size_t ysize = RoundUpTo(ysize_orig, block_dim);

  // Expands image size to the originally-allocated size.

  JXL_RETURN_IF_ERROR(in->ShrinkTo(xsize, ysize));

  for (size_t c = 0; c < 3; c++) {

    for (size_t y = 0; y < ysize_orig; y++) {

      float* JXL_RESTRICT row = in->PlaneRow(c, y);

      for (size_t x = xsize_orig; x < xsize; x++) {

        row[x] = row[xsize_orig - 1];

      }

    }

    const float* JXL_RESTRICT row_src = in->ConstPlaneRow(c, ysize_orig - 1);

    for (size_t y = ysize_orig; y < ysize; y++) {

      memcpy(in->PlaneRow(c, y), row_src, xsize * sizeof(float));

    }

  }

  return true;

}

static Status DoDownsampleImage(const ImageF& input, size_t factor,

                                ImageF* output) {

  JXL_ENSURE(factor != 1);

  JXL_RETURN_IF_ERROR(output->ShrinkTo(DivCeil(input.xsize(), factor),

                                       DivCeil(input.ysize(), factor)));

  size_t in_stride = input.PixelsPerRow();

  for (size_t y = 0; y < output->ysize(); y++) {

    float* row_out = output->Row(y);

    const float* row_in = input.Row(factor * y);

    for (size_t x = 0; x < output->xsize(); x++) {

      size_t cnt = 0;

      float sum = 0;

      for (size_t iy = 0; iy < factor && iy + factor * y < input.ysize();

           iy++) {

        for (size_t ix = 0; ix < factor && ix + factor * x < input.xsize();

             ix++) {

          sum += row_in[iy * in_stride + x * factor + ix];

          cnt++;

        }

      }

      row_out[x] = sum / cnt;

    }

  }

  return true;

}

StatusOr<ImageF> DownsampleImage(const ImageF& image, size_t factor) {

  ImageF downsampled;

  // Allocate extra space to avoid a reallocation when padding.

  JxlMemoryManager* memory_manager = image.memory_manager();

  JXL_ASSIGN_OR_RETURN(

      downsampled,

      ImageF::Create(memory_manager, DivCeil(image.xsize(), factor) + kBlockDim,

                     DivCeil(image.ysize(), factor) + kBlockDim));

  JXL_RETURN_IF_ERROR(DoDownsampleImage(image, factor, &downsampled));

  return downsampled;

}

StatusOr<Image3F> DownsampleImage(const Image3F& opsin, size_t factor) {

  JXL_ENSURE(factor != 1);

  // Allocate extra space to avoid a reallocation when padding.

  Image3F downsampled;

  JxlMemoryManager* memory_manager = opsin.memory_manager();

  JXL_ASSIGN_OR_RETURN(

      downsampled, Image3F::Create(memory_manager,

                                   DivCeil(opsin.xsize(), factor) + kBlockDim,

                                   DivCeil(opsin.ysize(), factor) + kBlockDim));

  JXL_RETURN_IF_ERROR(downsampled.ShrinkTo(downsampled.xsize() - kBlockDim,

                                           downsampled.ysize() - kBlockDim));

  for (size_t c = 0; c < 3; c++) {

    JXL_RETURN_IF_ERROR(

        DoDownsampleImage(opsin.Plane(c), factor, &downsampled.Plane(c)));

  }

  return downsampled;

}

}  // namespace jxl