// Copyright (c) 2012 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 UI_COMPOSITOR_LAYER_ANIMATION_SEQUENCE_H_
#define UI_COMPOSITOR_LAYER_ANIMATION_SEQUENCE_H_

#include <vector>

#include "base/gtest_prod_util.h"
#include "base/memory/linked_ptr.h"
#include "base/memory/weak_ptr.h"
#include "base/observer_list.h"
#include "base/time.h"
#include "ui/compositor/compositor_export.h"
#include "ui/compositor/layer_animation_element.h"

namespace ui {

class LayerAnimationDelegate;
class LayerAnimationObserver;

// Contains a collection of layer animation elements to be played one after
// another. Although it has a similar interface to LayerAnimationElement, it is
// not a LayerAnimationElement (i.e., it is not permitted to have a sequence in
// a sequence). Sequences own their elements, and sequences are themselves owned
// by a LayerAnimator.
//
// TODO(vollick) Create a 'blended' sequence for transitioning between
// sequences.
// TODO(vollick) Eventually, the LayerAnimator will switch to a model where new
// work is scheduled rather than calling methods directly. This should make it
// impossible for temporary pointers to running animations to go stale. When
// this happens, there will be no need for LayerAnimationSequences to support
// weak pointers.
class COMPOSITOR_EXPORT LayerAnimationSequence
    : public base::SupportsWeakPtr<LayerAnimationSequence> {
 public:
  LayerAnimationSequence();
  // Takes ownership of the given element and adds it to the sequence.
  explicit LayerAnimationSequence(LayerAnimationElement* element);
  virtual ~LayerAnimationSequence();

  // Sets the start time for the animation. This must be called before the
  // first call to {Progress, IsFinished}. Once the animation is finished, this
  // must be called again in order to restart the animation.
  void set_start_time(base::TimeTicks start_time) { start_time_ = start_time; }
  base::TimeTicks start_time() const { return start_time_; }

  // Updates the delegate to the appropriate value for |now|. Requests a
  // redraw if it is required.
  void Progress(base::TimeTicks now, LayerAnimationDelegate* delegate);

  // Returns true if calling Progress now, with the given time, will finish
  // the animation.
  bool IsFinished(base::TimeTicks time);

  // Updates the delegate to the end of the animation; if this sequence is
  // cyclic, updates the delegate to the end of one cycle of the sequence.
  void ProgressToEnd(LayerAnimationDelegate* delegate);

  // Sets the target value to the value that would have been set had
  // the sequence completed. Does nothing if the sequence is cyclic.
  void GetTargetValue(LayerAnimationElement::TargetValue* target) const;

  // Aborts the given animation.
  void Abort();

  // All properties modified by the sequence.
  const LayerAnimationElement::AnimatableProperties& properties() const {
    return properties_;
  }

  // Adds an element to the sequence. The sequences takes ownership of this
  // element.
  void AddElement(LayerAnimationElement* element);

  // Sequences can be looped indefinitely.
  void set_is_cyclic(bool is_cyclic) { is_cyclic_ = is_cyclic; }
  bool is_cyclic() const { return is_cyclic_; }

  // Returns true if this sequence has at least one element affecting a
  // property in |other|.
  bool HasCommonProperty(
      const LayerAnimationElement::AnimatableProperties& other) const;

  // These functions are used for adding or removing observers from the observer
  // list. The observers are notified when animations end.
  void AddObserver(LayerAnimationObserver* observer);
  void RemoveObserver(LayerAnimationObserver* observer);

  // Called when the animator schedules this sequence.
  void OnScheduled();

  // Called when the animator is destroyed.
  void OnAnimatorDestroyed();

 private:
  typedef std::vector<linked_ptr<LayerAnimationElement> > Elements;

  FRIEND_TEST_ALL_PREFIXES(LayerAnimatorTest,
                           ObserverReleasedBeforeAnimationSequenceEnds);

  // Notifies the observers that this sequence has been scheduled.
  void NotifyScheduled();

  // Notifies the observers that this sequence has ended.
  void NotifyEnded();

  // Notifies the observers that this sequence has been aborted.
  void NotifyAborted();

  // The union of all the properties modified by all elements in the sequence.
  LayerAnimationElement::AnimatableProperties properties_;

  // The elements in the sequence.
  Elements elements_;

  // True if the sequence should be looped forever.
  bool is_cyclic_;

  // These are used when animating to efficiently find the next element.
  size_t last_element_;
  base::TimeTicks last_start_;

  // The start time of the current run of the sequence.
  base::TimeTicks start_time_;

  // These parties are notified when layer animations end.
  ObserverList<LayerAnimationObserver> observers_;

  DISALLOW_COPY_AND_ASSIGN(LayerAnimationSequence);
};

}  // namespace ui

#endif  // UI_COMPOSITOR_LAYER_ANIMATION_SEQUENCE_H_