/*
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 * modification, are permitted provided that the following conditions are
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 *     * Redistributions of source code must retain the above copyright
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 * in the documentation and/or other materials provided with the
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 * this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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#include "third_party/blink/renderer/core/animation/pending_animations.h"

#include "base/auto_reset.h"
#include "third_party/blink/renderer/core/animation/document_timeline.h"
#include "third_party/blink/renderer/core/animation/keyframe_effect.h"
#include "third_party/blink/renderer/core/dom/document.h"
#include "third_party/blink/renderer/core/frame/local_frame_view.h"
#include "third_party/blink/renderer/core/page/page.h"
#include "third_party/blink/renderer/platform/instrumentation/tracing/trace_event.h"

namespace blink {

void PendingAnimations::Add(Animation* animation) {
  DCHECK(animation);
  DCHECK_EQ(pending_.Find(animation), kNotFound);
  pending_.push_back(animation);

  Document* document = animation->GetDocument();
  if (document->View()) {
    document->View()->ScheduleAnimation(
        cc::BeginMainFrameReason::kCSSAnimation);
  }

  bool visible = document->GetPage() && document->GetPage()->IsPageVisible();
  if (!visible && !timer_.IsActive()) {
    // Verify the timer is not activated in cycles.
    CHECK(!inside_timer_fired_);
    timer_.StartOneShot(base::TimeDelta(), FROM_HERE);
  }
}

bool PendingAnimations::Update(
    const PaintArtifactCompositor* paint_artifact_compositor,
    bool start_on_compositor) {
  HeapVector<Member<Animation>> waiting_for_start_time;
  bool started_synchronized_on_compositor = false;

  HeapVector<Member<Animation>> animations;
  HeapVector<Member<Animation>> deferred;
  animations.swap(pending_);
  int compositor_group = NextCompositorGroup();

  for (auto& animation : animations) {
    bool had_compositor_animation =
        animation->HasActiveAnimationsOnCompositor() ||
        animation->CompositorPendingCancel();
    // Animations with a start time or non-monotonic timeline do not participate
    // in compositor start-time grouping.
    bool has_monotonic_timeline =
        animation->TimelineInternal() &&
        animation->TimelineInternal()->IsMonotonicallyIncreasing();
    // Note, not setting a compositor group means animation events may be
    // dropped or mis-routed since they'll all target group 1. This doesn't
    // cause any issues currently, since blink::Animation only implements
    // NotifyAnimationStarted, but it would be an issue if Blink ever wanted to
    // handle the other events in CompositorAnimationDelegate.
    bool use_compositor_group =
        !animation->StartTimeInternal() && has_monotonic_timeline;
    if (animation->PreCommit(use_compositor_group
                                 ? compositor_group
                                 : kCompositorGroupHasStartTime,
                             paint_artifact_compositor, start_on_compositor)) {
      if (animation->HasActiveAnimationsOnCompositor() &&
          !had_compositor_animation && use_compositor_group) {
        started_synchronized_on_compositor = true;
      }

      if (!animation->TimelineInternal() ||
          !animation->TimelineInternal()->IsActive()) {
        continue;
      }

      if (animation->Playing() && !animation->StartTimeInternal()) {
        // Scroll timelines get their start time set during timeline validation
        // and do not need to be added to the list. Once the start time is set
        // they must be re-added to the pending animations.
        if (has_monotonic_timeline) {
          waiting_for_start_time.push_back(animation.Get());
        }
      } else if (animation->PendingInternal()) {
        if (!has_monotonic_timeline && !animation->CurrentTimeInternal()) {
          // Animations attached to a scroll-timeline rely on a deferred start
          // time to determine the initial animation progress. Until the
          // animation has a current time, keep it in a pending state.
          deferred.push_back(animation);
        } else {
          DCHECK(animation->TimelineInternal()->IsActive() &&
                 animation->TimelineInternal()->CurrentTime() &&
                 animation->CurrentTimeInternal());
          // A pending animation that is not waiting on a start time does not
          // need
          // to be synchronized with animations that are starting up.
          // Nonetheless, it needs to notify the animation to resolve the ready
          // promise and commit the pending state.
          animation->NotifyReady(
              animation->TimelineInternal()->CurrentTime().value());
        }
      }
    } else if (animation->CurrentTimeInternal()) {
      // TODO(crbug.com/397451098): We shouldn't need to push these on a
      // deferred list for re-injection into the pending list. The start of the
      // animation on the compositor will trigger NotifyReady. Any change to the
      // animation that would affect the state of the animation must call
      // SetCompositorPending, which will add it back to the pending list.
      deferred.push_back(animation);
    }
  }

  // If any synchronized animations were started on the compositor, all
  // remaining synchronized animations need to wait for the synchronized
  // start time. Otherwise they may start immediately if animating on the main
  // thread.
  if (started_synchronized_on_compositor) {
    FlushWaitingNonCompositedAnimations();
    waiting_for_compositor_animation_start_.append_range(
        waiting_for_start_time);
  } else {
    // Main-threaded animations previously held up for sync with the compositor
    // are no longer held up.
    for (auto& animation : waiting_for_start_time) {
      if (animation->HasActiveAnimationsOnCompositor()) {
        // A composited animation needs to continue waiting, otherwise the
        // start time on the compositor and main-thread will be misaligned.
        if (animation->CompositorGroup() == compositor_group) {
          // Composited animation was restarting with a new compositor group.
          waiting_for_compositor_animation_start_.push_back(animation);
        }
        continue;
      }
      DCHECK(!animation->StartTimeInternal());
      DCHECK(animation->TimelineInternal()->IsActive() &&
             animation->TimelineInternal()->CurrentTime());
      animation->NotifyReady(
          animation->TimelineInternal()->CurrentTime().value());
    }
  }

  // FIXME: The postCommit should happen *after* the commit, not before.
  for (auto& animation : animations)
    animation->PostCommit();

  DCHECK(pending_.empty());
  DCHECK(start_on_compositor || deferred.empty());
  for (auto& animation : deferred) {
    animation->SetCompositorPending(
        Animation::CompositorPendingReason::kPendingUpdate);
  }
  DCHECK_EQ(pending_.size(), deferred.size());

  if (started_synchronized_on_compositor) {
    return true;
  }

  if (waiting_for_compositor_animation_start_.empty()) {
    return false;
  }

  // Check if we're still waiting for any compositor animations to start.
  for (auto& animation : waiting_for_compositor_animation_start_) {
    if (animation->HasActiveAnimationsOnCompositor()) {
      return true;
    }
  }

  // If not, go ahead and start any animations that were waiting.
  NotifyCompositorAnimationStarted(
      base::TimeTicks::Now().since_origin().InSecondsF());

  DCHECK_EQ(pending_.size(), deferred.size());
  return false;
}

void PendingAnimations::NotifyCompositorAnimationStarted(
    double monotonic_animation_start_time,
    int compositor_group) {
  TRACE_EVENT0("blink", "PendingAnimations::notifyCompositorAnimationStarted");

  HeapVector<Member<Animation>> animations;
  animations.swap(waiting_for_compositor_animation_start_);

  for (auto animation : animations) {
    if (animation->StartTimeInternal() || !animation->PendingInternal() ||
        !animation->TimelineInternal() ||
        !animation->TimelineInternal()->IsActive()) {
      // Already started or no longer relevant.
      continue;
    }
    if (!animation->CurrentTimeInternal()) {
      // Waiting on a deferred start time.
      continue;
    }
    if (compositor_group && animation->CompositorGroup() != compositor_group) {
      // Still waiting.
      waiting_for_compositor_animation_start_.push_back(animation);
      continue;
    }
    if (!animation->TimelineInternal()->IsMonotonicallyIncreasing()) {
      animation->NotifyReady(
          animation->TimelineInternal()->CurrentTime().value());
    } else {
      animation->NotifyReady(
          ANIMATION_TIME_DELTA_FROM_SECONDS(monotonic_animation_start_time) -
          animation->TimelineInternal()->ZeroTime());
    }
  }
}

int PendingAnimations::NextCompositorGroup() {
  do {
    // Wrap around, skipping reserved groups.
    ++compositor_group_;
  } while (compositor_group_ == kCompositorGroupAutoAssign ||
           compositor_group_ == kCompositorGroupHasStartTime);

  return compositor_group_;
}

void PendingAnimations::FlushWaitingNonCompositedAnimations() {
  if (waiting_for_compositor_animation_start_.empty())
    return;

  // Start any main thread animations that were scheduled to wait on
  // compositor synchronization from a previous frame. Otherwise, a
  // continuous influx of new composited animations could delay the start
  // of non-composited animations indefinitely (crbug.com/666710).
  HeapVector<Member<Animation>> animations;
  animations.swap(waiting_for_compositor_animation_start_);
  for (auto& animation : animations) {
    if (animation->HasActiveAnimationsOnCompositor()) {
      waiting_for_compositor_animation_start_.push_back(animation);
    } else if (animation->TimelineInternal() &&
               animation->TimelineInternal()->IsActive() &&
               animation->TimelineInternal()->CurrentTime().has_value() &&
               animation->CurrentTimeInternal()) {
      animation->NotifyReady(
          animation->TimelineInternal()->CurrentTime().value());
    }
  }
}

void PendingAnimations::Trace(Visitor* visitor) const {
  visitor->Trace(pending_);
  visitor->Trace(waiting_for_compositor_animation_start_);
  visitor->Trace(timer_);
}

void PendingAnimations::TimerFired(TimerBase*) {
  base::AutoReset<bool> mark_inside(&inside_timer_fired_, true);
  Update(nullptr, false);
}

}  // namespace blink