// 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.

#include "ash/home_screen/window_scale_animation.h"

#include "ash/public/cpp/shelf_config.h"
#include "ash/public/cpp/window_backdrop.h"
#include "ash/public/cpp/window_properties.h"
#include "ash/scoped_animation_disabler.h"
#include "ash/screen_util.h"
#include "ash/shelf/shelf.h"
#include "ash/shell.h"
#include "ash/wm/window_state.h"
#include "ash/wm/window_util.h"
#include "base/time/time.h"
#include "ui/aura/window.h"
#include "ui/compositor/layer.h"
#include "ui/compositor/layer_animator.h"
#include "ui/compositor/scoped_layer_animation_settings.h"
#include "ui/gfx/animation/tween.h"
#include "ui/gfx/transform.h"

namespace ash {

namespace {

// The time to do window transform to scale up to its original position or
// scale down to homescreen animation.
constexpr base::TimeDelta kWindowScaleUpOrDownTime =
    base::TimeDelta::FromMilliseconds(350);

// The delay to do window opacity fade out when scaling down the dragged window.
constexpr base::TimeDelta kWindowFadeOutDelay =
    base::TimeDelta::FromMilliseconds(100);

// The window scale down factor if we head to home screen after drag ends.
constexpr float kWindowScaleDownFactor = 0.001f;

}  // namespace

WindowScaleAnimation::WindowScaleAnimation(aura::Window* window,
                                           WindowScaleType scale_type,
                                           base::OnceClosure opt_callback)
    : window_(window),
      opt_callback_(std::move(opt_callback)),
      scale_type_(scale_type) {
  window_observer_.Add(window);
  WindowBackdrop::Get(window)->DisableBackdrop();

  ui::ScopedLayerAnimationSettings settings(window_->layer()->GetAnimator());
  settings.SetTransitionDuration(kWindowScaleUpOrDownTime);
  settings.SetPreemptionStrategy(
      ui::LayerAnimator::IMMEDIATELY_ANIMATE_TO_NEW_TARGET);
  settings.SetTweenType(gfx::Tween::FAST_OUT_SLOW_IN);
  settings.AddObserver(this);
  if (scale_type_ == WindowScaleType::kScaleDownToShelf) {
    window_->layer()->GetAnimator()->SchedulePauseForProperties(
        kWindowFadeOutDelay, ui::LayerAnimationElement::OPACITY);
    window_->layer()->SetTransform(GetWindowTransformToShelf());
    window_->layer()->SetOpacity(0.f);
  } else {
    window_->layer()->SetTransform(gfx::Transform());
  }
}

WindowScaleAnimation::~WindowScaleAnimation() {
  if (!opt_callback_.is_null())
    std::move(opt_callback_).Run();
}

void WindowScaleAnimation::OnImplicitAnimationsCompleted() {
  if (scale_type_ == WindowScaleType::kScaleDownToShelf) {
    // Minimize the dragged window after transform animation is completed.
    window_util::MinimizeAndHideWithoutAnimation({window_});

    // Reset its transform to identity transform and its original backdrop mode.
    window_->layer()->SetTransform(gfx::Transform());
    window_->layer()->SetOpacity(1.f);
  }
  WindowBackdrop::Get(window_)->RestoreBackdrop();

  delete this;
}

void WindowScaleAnimation::OnWindowDestroying(aura::Window* window) {
  window_ = nullptr;
  delete this;
}

gfx::Transform WindowScaleAnimation::GetWindowTransformToShelf() {
  // The origin of bounds returned by GetBoundsInScreen() is transformed using
  // the window's transform. The transform that should be applied to the window
  // is calculated relative to the window bounds with no transforms applied, and
  // thus need the un-transformed window origin.
  const gfx::Rect window_bounds = window_->GetBoundsInScreen();
  gfx::Point origin_without_transform = window_bounds.origin();
  window_->transform().TransformPointReverse(&origin_without_transform);

  gfx::Transform transform;
  Shelf* shelf = Shelf::ForWindow(window_);

  const gfx::Rect shelf_item_bounds =
      shelf->GetScreenBoundsOfItemIconForWindow(window_);

  if (!shelf_item_bounds.IsEmpty()) {
    transform.Translate(shelf_item_bounds.x() - origin_without_transform.x(),
                        shelf_item_bounds.y() - origin_without_transform.y());
    transform.Scale(
        float(shelf_item_bounds.width()) / float(window_bounds.width()),
        float(shelf_item_bounds.height()) / float(window_bounds.height()));
  } else {
    const gfx::Rect shelf_bounds = shelf->GetIdealBounds();
    transform.Translate(
        shelf_bounds.CenterPoint().x() - origin_without_transform.x(),
        shelf_bounds.CenterPoint().y() - origin_without_transform.y());
    transform.Scale(kWindowScaleDownFactor, kWindowScaleDownFactor);
  }
  return transform;
}

}  // namespace ash