// Copyright 2015 Google Inc. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

#include "cobalt/renderer/rasterizer/skia/skia/src/effects/SkYUV2RGBShader.h"

#include <algorithm>

#include "base/logging.h"
#include "third_party/skia/include/core/SkColorPriv.h"
#include "third_party/skia/include/core/SkShader.h"
#include "third_party/skia/include/core/SkString.h"
#include "third_party/skia/include/core/SkWriteBuffer.h"
#include "third_party/skia/src/core/SkReadBuffer.h"
#include "third_party/skia/src/gpu/effects/GrYUVtoRGBEffect.h"

SkYUV2RGBShader::SkYUV2RGBShader(
    SkYUVColorSpace color_space,
    const SkBitmap& y_bitmap, const SkMatrix& y_matrix,
    const SkBitmap& u_bitmap, const SkMatrix& u_matrix,
    const SkBitmap& v_bitmap, const SkMatrix& v_matrix) :
    color_space_(color_space),
    y_bitmap_(y_bitmap), y_matrix_(y_matrix),
    u_bitmap_(u_bitmap), u_matrix_(u_matrix),
    v_bitmap_(v_bitmap), v_matrix_(v_matrix) {
  DCHECK(!y_bitmap_.isNull());
  DCHECK(!u_bitmap_.isNull());
  DCHECK(!v_bitmap_.isNull());
  InitializeShaders();
}

void SkYUV2RGBShader::InitializeShaders() {
  y_shader_ = SkShader::CreateBitmapShader(
      y_bitmap_, SkShader::kClamp_TileMode, SkShader::kClamp_TileMode,
      &y_matrix_);
  DCHECK(y_shader_);

  u_shader_ = SkShader::CreateBitmapShader(
      u_bitmap_, SkShader::kClamp_TileMode, SkShader::kClamp_TileMode,
      &u_matrix_);
  DCHECK(u_shader_);

  v_shader_ = SkShader::CreateBitmapShader(
      v_bitmap_, SkShader::kClamp_TileMode, SkShader::kClamp_TileMode,
      &v_matrix_);
  DCHECK(v_shader_);
}

#ifdef SK_SUPPORT_LEGACY_DEEPFLATTENING
SkYUV2RGBShader::SkYUV2RGBShader(SkReadBuffer& buffer) : INHERITED(buffer) {
  color_space_ = static_cast<SkYUVColorSpace>(buffer.readInt());
  buffer.readBitmap(&y_bitmap_);
  buffer.readMatrix(&y_matrix_);
  buffer.readBitmap(&u_bitmap_);
  buffer.readMatrix(&u_matrix_);
  buffer.readBitmap(&v_bitmap_);
  buffer.readMatrix(&v_matrix_);
  InitializeShaders();
}
#endif

SkYUV2RGBShader::~SkYUV2RGBShader() {
  y_shader_->unref();
  u_shader_->unref();
  v_shader_->unref();
}

SkFlattenable* SkYUV2RGBShader::CreateProc(SkReadBuffer& buffer) {
  SkYUVColorSpace color_space = static_cast<SkYUVColorSpace>(buffer.readInt());

  SkBitmap y_bitmap;
  if (!buffer.readBitmap(&y_bitmap)) {
    return NULL;
  }
  y_bitmap.setImmutable();
  SkMatrix y_matrix;
  buffer.readMatrix(&y_matrix);

  SkBitmap u_bitmap;
  if (!buffer.readBitmap(&u_bitmap)) {
    return NULL;
  }
  u_bitmap.setImmutable();
  SkMatrix u_matrix;
  buffer.readMatrix(&u_matrix);

  SkBitmap v_bitmap;
  if (!buffer.readBitmap(&v_bitmap)) {
    return NULL;
  }
  v_bitmap.setImmutable();
  SkMatrix v_matrix;
  buffer.readMatrix(&v_matrix);

  return SkNEW_ARGS(
      SkYUV2RGBShader,
      (color_space,
       y_bitmap, y_matrix, u_bitmap, u_matrix, v_bitmap, v_matrix));
}

void SkYUV2RGBShader::flatten(SkWriteBuffer& buffer) const {
  buffer.writeInt(color_space_);
  buffer.writeBitmap(y_bitmap_);
  buffer.writeMatrix(y_matrix_);
  buffer.writeBitmap(u_bitmap_);
  buffer.writeMatrix(u_matrix_);
  buffer.writeBitmap(v_bitmap_);
  buffer.writeMatrix(v_matrix_);
}

uint32_t SkYUV2RGBShader::YUV2RGBShaderContext::getFlags() const {
  return 0;
}

SkShader::Context* SkYUV2RGBShader::onCreateContext(
    const ContextRec& rec, void* storage) const {
  char* shaderContextStorage =
      static_cast<char*>(storage) + sizeof(YUV2RGBShaderContext);
  SkShader::Context* y_shader_context =
      y_shader_->createContext(rec, shaderContextStorage);
  DCHECK(y_shader_context);
  shaderContextStorage += y_shader_->contextSize();
  SkShader::Context* u_shader_context =
      u_shader_->createContext(rec, shaderContextStorage);
  DCHECK(u_shader_context);
  shaderContextStorage += u_shader_->contextSize();
  SkShader::Context* v_shader_context =
      v_shader_->createContext(rec, shaderContextStorage);
  DCHECK(v_shader_context);

  return SkNEW_PLACEMENT_ARGS(
    storage, YUV2RGBShaderContext,
    (color_space_, *this,
     y_shader_context, u_shader_context, v_shader_context, rec));
}

size_t SkYUV2RGBShader::contextSize() const {
  return sizeof(YUV2RGBShaderContext) +
         y_shader_->contextSize() +
         u_shader_->contextSize() +
         v_shader_->contextSize();
}

SkYUV2RGBShader::YUV2RGBShaderContext::YUV2RGBShaderContext(
    SkYUVColorSpace color_space, const SkYUV2RGBShader& yuv2rgb_shader,
    SkShader::Context* y_shader_context, SkShader::Context* u_shader_context,
    SkShader::Context* v_shader_context,
    const ContextRec& rec)
  : INHERITED(yuv2rgb_shader, rec)
  , color_space_(color_space)
  , y_shader_context_(y_shader_context)
  , u_shader_context_(u_shader_context)
  , v_shader_context_(v_shader_context) {}

SkYUV2RGBShader::YUV2RGBShaderContext::~YUV2RGBShaderContext() {
  y_shader_context_->~Context();
  u_shader_context_->~Context();
  v_shader_context_->~Context();
}

void SkYUV2RGBShader::YUV2RGBShaderContext::shadeSpan(
    int x, int y, SkPMColor result[], int count) {
  static const int kPixelCountPerSpan = 64;
  SkPMColor y_values[kPixelCountPerSpan];
  SkPMColor u_values[kPixelCountPerSpan];
  SkPMColor v_values[kPixelCountPerSpan];

  DCHECK_EQ(kRec709_SkYUVColorSpace, color_space_) <<
      "Currently we only support the BT.709 YUV colorspace.";

  do {
    int count_in_chunk =
        count > kPixelCountPerSpan ? kPixelCountPerSpan : count;

    y_shader_context_->shadeSpan(x, y, y_values, count_in_chunk);
    u_shader_context_->shadeSpan(x, y, u_values, count_in_chunk);
    v_shader_context_->shadeSpan(x, y, v_values, count_in_chunk);

    for (int i = 0; i < count_in_chunk; ++i) {
      int32_t y_value = SkColorGetA(y_values[i]) - 16;
      int32_t u_value = SkColorGetA(u_values[i]) - 128;
      int32_t v_value = SkColorGetA(v_values[i]) - 128;

      const float kA = 1.164f;
      const float kB = -0.213f;
      const float kC = 2.112f;
      const float kD = 1.793f;
      const float kE = -0.533f;
      int32_t r_unclamped = static_cast<int32_t>(kA * y_value + kD * v_value);
      int32_t g_unclamped =
          static_cast<int32_t>(kA * y_value + kB * u_value + kE * v_value);
      int32_t b_unclamped = static_cast<int32_t>(kA * y_value + kC * u_value);

      int32_t r_clamped =
          std::min<int32_t>(255, std::max<int32_t>(0, r_unclamped));
      int32_t g_clamped =
          std::min<int32_t>(255, std::max<int32_t>(0, g_unclamped));
      int32_t b_clamped =
          std::min<int32_t>(255, std::max<int32_t>(0, b_unclamped));

      result[i] = SkPackARGB32NoCheck(255, r_clamped, g_clamped, b_clamped);
    }
    result += count_in_chunk;
    x += count_in_chunk;
    count -= count_in_chunk;
  } while (count > 0);
}

void SkYUV2RGBShader::YUV2RGBShaderContext::shadeSpan16(
    int x, int y, uint16_t result[], int count) {
  NOTREACHED();
}

#ifndef SK_IGNORE_TO_STRING
void SkYUV2RGBShader::toString(SkString* str) const {
  str->append("SkYUV2RGBShader: (");

  str->append("Y Shader: ");
  y_shader_->toString(str);
  str->append("U Shader: ");
  u_shader_->toString(str);
  str->append("V Shader: ");
  v_shader_->toString(str);

  this->INHERITED::toString(str);

  str->append(")");
}
#endif  // SK_IGNORE_TO_STRING

#if SK_SUPPORT_GPU

bool SkYUV2RGBShader::asFragmentProcessor(GrContext*, const SkPaint& paint,
                                          const SkMatrix* localMatrix, GrColor*,
                                          GrFragmentProcessor** fp) const {
  // Code snippet taken from SkBitmapProcShader::asFragmentProcessor().
  SkMatrix matrix;
  matrix.setIDiv(y_bitmap_.width(), y_bitmap_.height());

  SkMatrix lmInverse;
  if (!y_shader_->getLocalMatrix().invert(&lmInverse)) {
      return false;
  }
  if (localMatrix) {
      SkMatrix inv;
      if (!localMatrix->invert(&inv)) {
          return false;
      }
      lmInverse.postConcat(inv);
  }
  matrix.preConcat(lmInverse);

  GrTextureParams::FilterMode filter_mode =
      paint.getFilterLevel() == SkPaint::kNone_FilterLevel
          ? GrTextureParams::kNone_FilterMode
          : GrTextureParams::kBilerp_FilterMode;
  GrTextureParams texture_params;
  texture_params.setFilterMode(filter_mode);

  *fp = GrYUVtoRGBEffect::Create(y_bitmap_.getTexture(), u_bitmap_.getTexture(),
                                 v_bitmap_.getTexture(), matrix, texture_params,
                                 kRec709_SkYUVColorSpace, false);
  return true;
}

#endif  // SK_SUPPORT_GPU