// Copyright 2013 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "cc/paint/filter_operations.h"

#include <stddef.h>

#include <algorithm>
#include <cmath>
#include <numeric>
#include <utility>

#include "base/feature_list.h"
#include "base/trace_event/traced_value.h"
#include "base/values.h"
#include "cc/base/features.h"
#include "cc/paint/filter_operation.h"
#include "ui/gfx/geometry/rect.h"
#include "ui/gfx/geometry/rect_conversions.h"

namespace cc {

FilterOperations::FilterOperations() = default;

FilterOperations::FilterOperations(const FilterOperations& other) = default;

FilterOperations::FilterOperations(std::vector<FilterOperation>&& operations)
    : operations_(std::move(operations)) {}

FilterOperations::~FilterOperations() = default;

FilterOperations& FilterOperations::operator=(const FilterOperations& other) =
    default;

FilterOperations& FilterOperations::operator=(FilterOperations&& other) {
  operations_ = std::move(other.operations_);
  return *this;
}

bool FilterOperations::operator==(const FilterOperations& other) const {
  if (other.size() != size())
    return false;
  for (size_t i = 0; i < size(); ++i) {
    if (other.at(i) != at(i))
      return false;
  }
  return true;
}

void FilterOperations::Append(const FilterOperation& filter) {
  operations_.push_back(filter);
}

void FilterOperations::Clear() {
  operations_.clear();
}

bool FilterOperations::IsEmpty() const {
  return operations_.empty();
}

gfx::Rect FilterOperations::MapRect(const gfx::Rect& rect,
                                    const std::optional<SkMatrix>& ctm) const {
  auto accumulate_rect = [&ctm](const gfx::Rect& rect,
                                const FilterOperation& op) {
    return op.MapRect(rect, ctm);
  };
  return std::accumulate(operations_.begin(), operations_.end(), rect,
                         accumulate_rect);
}

gfx::Rect FilterOperations::MapRectReverse(const gfx::Rect& rect,
                                           const SkMatrix& ctm) const {
  auto accumulate_rect = [&ctm](const gfx::Rect& rect,
                                const FilterOperation& op) {
    return op.MapRectReverse(rect, ctm);
  };
  return std::accumulate(operations_.rbegin(), operations_.rend(), rect,
                         accumulate_rect);
}

gfx::Rect FilterOperations::ExpandRect(const gfx::Rect& rect,
                                       const SkMatrix& ctm) const {
  gfx::Rect result = MapRect(rect, ctm);
  result.Union(MapRectReverse(rect, ctm));
  return result;
}

bool FilterOperations::HasFilterThatMovesPixels() const {
  for (size_t i = 0; i < operations_.size(); ++i) {
    const FilterOperation& op = operations_[i];
    switch (op.type()) {
      case FilterOperation::BLUR:
      case FilterOperation::DROP_SHADOW:
      case FilterOperation::ZOOM:
      case FilterOperation::OFFSET:
        return true;
      case FilterOperation::REFERENCE:
        // TODO(hendrikw): SkImageFilter needs a function that tells us if the
        // filter can move pixels. See crbug.com/523538.
        return true;
      case FilterOperation::OPACITY:
      case FilterOperation::COLOR_MATRIX:
      case FilterOperation::GRAYSCALE:
      case FilterOperation::SEPIA:
      case FilterOperation::SATURATE:
      case FilterOperation::HUE_ROTATE:
      case FilterOperation::INVERT:
      case FilterOperation::BRIGHTNESS:
      case FilterOperation::CONTRAST:
      case FilterOperation::SATURATING_BRIGHTNESS:
      case FilterOperation::ALPHA_THRESHOLD:
        break;
    }
  }
  return false;
}

bool FilterOperations::HasFilterThatAffectsOpacity() const {
  for (size_t i = 0; i < operations_.size(); ++i) {
    const FilterOperation& op = operations_[i];
    // TODO(ajuma): Make this smarter for reference filters. Once SkImageFilter
    // can report affectsOpacity(), call that.
    switch (op.type()) {
      case FilterOperation::OPACITY:
      case FilterOperation::BLUR:
      case FilterOperation::DROP_SHADOW:
      case FilterOperation::ZOOM:
      case FilterOperation::REFERENCE:
      case FilterOperation::ALPHA_THRESHOLD:
        return true;
      case FilterOperation::COLOR_MATRIX: {
        auto& matrix = op.matrix();
        if (matrix[15] || matrix[16] || matrix[17] || matrix[18] != 1 ||
            matrix[19])
          return true;
        break;
      }
      case FilterOperation::GRAYSCALE:
      case FilterOperation::SEPIA:
      case FilterOperation::SATURATE:
      case FilterOperation::HUE_ROTATE:
      case FilterOperation::INVERT:
      case FilterOperation::BRIGHTNESS:
      case FilterOperation::CONTRAST:
      case FilterOperation::SATURATING_BRIGHTNESS:
      case FilterOperation::OFFSET:
        break;
    }
  }
  return false;
}

bool FilterOperations::HasReferenceFilter() const {
  return HasFilterOfType(FilterOperation::REFERENCE);
}

bool FilterOperations::HasFilterOfType(FilterOperation::FilterType type) const {
  return std::ranges::contains(operations_, type, &FilterOperation::type);
}

FilterOperations FilterOperations::Blend(const FilterOperations& from,
                                         double progress) const {
  if (HasReferenceFilter() || from.HasReferenceFilter())
    return *this;

  bool from_is_longer = from.size() > size();

  size_t shorter_size, longer_size;
  if (size() == from.size()) {
    shorter_size = longer_size = size();
  } else if (from_is_longer) {
    longer_size = from.size();
    shorter_size = size();
  } else {
    longer_size = size();
    shorter_size = from.size();
  }

  for (size_t i = 0; i < shorter_size; i++) {
    if (from.at(i).type() != at(i).type())
      return *this;
  }

  FilterOperations blended_filters;
  for (size_t i = 0; i < shorter_size; i++) {
    blended_filters.Append(
        FilterOperation::Blend(&from.at(i), &at(i), progress));
  }

  if (from_is_longer) {
    for (size_t i = shorter_size; i < longer_size; i++) {
      blended_filters.Append(
          FilterOperation::Blend(&from.at(i), nullptr, progress));
    }
  } else {
    for (size_t i = shorter_size; i < longer_size; i++)
      blended_filters.Append(FilterOperation::Blend(nullptr, &at(i), progress));
  }

  return blended_filters;
}

bool FilterOperations::AllowsLCDText() const {
  if (operations_.empty()) {
    return true;
  }
  // Assumes any complex filter can cause color fringing of LCD-text pixels.
  if (operations_.size() > 1) {
    return false;
  }
  switch (operations_[0].type()) {
    // These filters reduce or don't change the color difference between
    // LCD-text pixels and text pixels.
    case FilterOperation::GRAYSCALE:
    case FilterOperation::SEPIA:
    case FilterOperation::OPACITY:
    case FilterOperation::BRIGHTNESS:
    // A blur filter may change color, but it's very common, and the color
    // change of LCD-text pixels is not obvious.
    case FilterOperation::BLUR:
    // A drop shadow draws over the original pixels.
    case FilterOperation::DROP_SHADOW:
      return true;

    // These filters are good for LCD text if they reduce or don't change
    // contrast/saturation.
    case FilterOperation::CONTRAST:
    case FilterOperation::SATURATE:
      return operations_[0].amount() <= 1;

    // Invert<=50% is like combined grayscale and contrast<100%.
    case FilterOperation::INVERT:
      return operations_[0].amount() <= 0.5;

    // Other filters may change colors of pixels dramatically, or are not or
    // rarely used in web.
    case FilterOperation::COLOR_MATRIX:
    case FilterOperation::HUE_ROTATE:
    case FilterOperation::ZOOM:
    case FilterOperation::REFERENCE:
    case FilterOperation::SATURATING_BRIGHTNESS:
    case FilterOperation::ALPHA_THRESHOLD:
    case FilterOperation::OFFSET:
      return false;
  }
}

void FilterOperations::AsValueInto(
    base::trace_event::TracedValue* value) const {
  for (size_t i = 0; i < operations_.size(); ++i) {
    value->BeginDictionary();
    operations_[i].AsValueInto(value);
    value->EndDictionary();
  }
}

std::string FilterOperations::ToString() const {
  base::trace_event::TracedValueJSON value;
  value.BeginArray("FilterOperations");
  AsValueInto(&value);
  value.EndArray();
  return value.ToJSON();
}

}  // namespace cc