// Copyright 2019 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef THIRD_PARTY_BLINK_RENDERER_CORE_ANIMATION_INTERPOLABLE_TRANSFORM_LIST_H_
#define THIRD_PARTY_BLINK_RENDERER_CORE_ANIMATION_INTERPOLABLE_TRANSFORM_LIST_H_

#include <memory>
#include "third_party/blink/renderer/core/animation/interpolable_value.h"
#include "third_party/blink/renderer/platform/transforms/transform_operations.h"
#include "third_party/blink/renderer/platform/wtf/casting.h"

namespace blink {

class CSSValue;
class StyleResolverState;

// Represents a blink::TransformOperations, converted into a form that can be
// interpolated from/to.
class CORE_EXPORT InterpolableTransformList final : public InterpolableValue {
 public:
  InterpolableTransformList(TransformOperations&& operations)
      : operations_(std::move(operations)) {}

  static std::unique_ptr<InterpolableTransformList> Create(
      TransformOperations&&);
  static std::unique_ptr<InterpolableTransformList> ConvertCSSValue(
      const CSSValue&,
      const StyleResolverState*);

  // Return the underlying TransformOperations. Usually called after composition
  // and interpolation, to apply the results back to the style.
  TransformOperations operations() const { return operations_; }

  void PreConcat(const InterpolableTransformList& underlying);
  void AccumulateOnto(const InterpolableTransformList& underlying);

  // InterpolableValue implementation:
  void Interpolate(const InterpolableValue& to,
                   const double progress,
                   InterpolableValue& result) const final;
  bool IsTransformList() const final { return true; }
  bool Equals(const InterpolableValue& other) const final {
    NOTREACHED();
    return false;
  }
  void Scale(double scale) final { NOTREACHED(); }
  void Add(const InterpolableValue& other) final { NOTREACHED(); }
  void AssertCanInterpolateWith(const InterpolableValue& other) const final;

 private:
  InterpolableTransformList* RawClone() const final {
    return new InterpolableTransformList(TransformOperations(operations_));
  }
  InterpolableTransformList* RawCloneAndZero() const final {
    NOTREACHED();
    return nullptr;
  }

  TransformOperations operations_;
};

template <>
struct DowncastTraits<InterpolableTransformList> {
  static bool AllowFrom(const InterpolableValue& interpolable_value) {
    return interpolable_value.IsTransformList();
  }
};

}  // namespace blink

#endif  // THIRD_PARTY_BLINK_RENDERER_CORE_ANIMATION_INTERPOLABLE_TRANSFORM_LIST_H_