/*
 * Copyright (C) 2013 Google Inc. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 *
 *     * Redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above
 * copyright notice, this list of conditions and the following disclaimer
 * in the documentation and/or other materials provided with the
 * distribution.
 *     * Neither the name of Google Inc. nor the names of its
 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include "core/frame/VisualViewport.h"

#include <memory>
#include "core/dom/DOMNodeIds.h"
#include "core/dom/TaskRunnerHelper.h"
#include "core/frame/FrameView.h"
#include "core/frame/LocalFrame.h"
#include "core/frame/LocalFrameClient.h"
#include "core/frame/PageScaleConstraints.h"
#include "core/frame/PageScaleConstraintsSet.h"
#include "core/frame/RootFrameViewport.h"
#include "core/frame/Settings.h"
#include "core/layout/TextAutosizer.h"
#include "core/layout/compositing/PaintLayerCompositor.h"
#include "core/page/ChromeClient.h"
#include "core/page/Page.h"
#include "core/page/scrolling/ScrollingCoordinator.h"
#include "core/probe/CoreProbes.h"
#include "platform/Histogram.h"
#include "platform/geometry/DoubleRect.h"
#include "platform/geometry/FloatSize.h"
#include "platform/graphics/CompositorMutableProperties.h"
#include "platform/graphics/GraphicsLayer.h"
#include "platform/instrumentation/tracing/TraceEvent.h"
#include "platform/scroll/Scrollbar.h"
#include "platform/scroll/ScrollbarThemeOverlay.h"
#include "public/platform/WebCompositorSupport.h"
#include "public/platform/WebScrollbar.h"
#include "public/platform/WebScrollbarLayer.h"

namespace blink {

VisualViewport::VisualViewport(Page& owner)
    : page_(&owner),
      scale_(1),
      browser_controls_adjustment_(0),
      max_page_scale_(-1),
      track_pinch_zoom_stats_for_page_(false) {
  Reset();
}

VisualViewport::~VisualViewport() {
  SendUMAMetrics();
}

DEFINE_TRACE(VisualViewport) {
  visitor->Trace(page_);
  ScrollableArea::Trace(visitor);
}

void VisualViewport::UpdateStyleAndLayoutIgnorePendingStylesheets() const {
  if (!MainFrame())
    return;

  if (Document* document = MainFrame()->GetDocument())
    document->UpdateStyleAndLayoutIgnorePendingStylesheets();
}

void VisualViewport::EnqueueScrollEvent() {
  if (!RuntimeEnabledFeatures::visualViewportAPIEnabled())
    return;

  if (Document* document = MainFrame()->GetDocument())
    document->EnqueueVisualViewportScrollEvent();
}

void VisualViewport::EnqueueResizeEvent() {
  if (!RuntimeEnabledFeatures::visualViewportAPIEnabled())
    return;

  if (Document* document = MainFrame()->GetDocument())
    document->EnqueueVisualViewportResizeEvent();
}

void VisualViewport::SetSize(const IntSize& size) {
  if (size_ == size)
    return;

  TRACE_EVENT2("blink", "VisualViewport::setSize", "width", size.Width(),
               "height", size.Height());
  bool width_did_change = size.Width() != size_.Width();
  size_ = size;

  if (inner_viewport_container_layer_) {
    inner_viewport_container_layer_->SetSize(FloatSize(size_));

    // Need to re-compute sizes for the overlay scrollbars.
    InitializeScrollbars();
  }

  if (!MainFrame())
    return;

  EnqueueResizeEvent();

  bool autosizer_needs_updating =
      width_did_change && MainFrame()->GetSettings() &&
      MainFrame()->GetSettings()->TextAutosizingEnabled();

  if (autosizer_needs_updating) {
    // This needs to happen after setting the m_size member since it'll be read
    // in the update call.
    if (TextAutosizer* text_autosizer =
            MainFrame()->GetDocument()->GetTextAutosizer())
      text_autosizer->UpdatePageInfoInAllFrames();
  }
}

void VisualViewport::Reset() {
  SetScaleAndLocation(1, FloatPoint());
}

void VisualViewport::MainFrameDidChangeSize() {
  TRACE_EVENT0("blink", "VisualViewport::mainFrameDidChangeSize");

  // In unit tests we may not have initialized the layer tree.
  if (inner_viewport_scroll_layer_)
    inner_viewport_scroll_layer_->SetSize(FloatSize(ContentsSize()));

  ClampToBoundaries();
}

FloatSize VisualViewport::VisibleSize() const {
  FloatSize scaled_size(size_);
  scaled_size.Expand(0, browser_controls_adjustment_);
  scaled_size.Scale(1 / scale_);
  return scaled_size;
}

FloatRect VisualViewport::VisibleRect() const {
  return FloatRect(FloatPoint(GetScrollOffset()), VisibleSize());
}

FloatRect VisualViewport::VisibleRectInDocument() const {
  if (!MainFrame() || !MainFrame()->View())
    return FloatRect();

  FloatPoint view_location =
      FloatPoint(MainFrame()->View()->GetScrollableArea()->GetScrollOffset());
  return FloatRect(view_location, VisibleSize());
}

FloatPoint VisualViewport::ViewportCSSPixelsToRootFrame(
    const FloatPoint& point) const {
  // Note, this is in CSS Pixels so we don't apply scale.
  FloatPoint point_in_root_frame = point;
  point_in_root_frame.Move(GetScrollOffset());
  return point_in_root_frame;
}

void VisualViewport::SetLocation(const FloatPoint& new_location) {
  SetScaleAndLocation(scale_, new_location);
}

void VisualViewport::Move(const ScrollOffset& delta) {
  SetLocation(FloatPoint(offset_ + delta));
}

void VisualViewport::SetScale(float scale) {
  SetScaleAndLocation(scale, FloatPoint(offset_));
}

double VisualViewport::OffsetLeft() const {
  if (!MainFrame())
    return 0;

  UpdateStyleAndLayoutIgnorePendingStylesheets();

  return AdjustScrollForAbsoluteZoom(VisibleRect().X(),
                                     MainFrame()->PageZoomFactor());
}

double VisualViewport::OffsetTop() const {
  if (!MainFrame())
    return 0;

  UpdateStyleAndLayoutIgnorePendingStylesheets();

  return AdjustScrollForAbsoluteZoom(VisibleRect().Y(),
                                     MainFrame()->PageZoomFactor());
}

double VisualViewport::Width() const {
  if (!MainFrame())
    return 0;

  UpdateStyleAndLayoutIgnorePendingStylesheets();

  float width = AdjustScrollForAbsoluteZoom(VisibleSize().Width(),
                                            MainFrame()->PageZoomFactor());
  return width - MainFrame()->View()->VerticalScrollbarWidth() / scale_;
}

double VisualViewport::Height() const {
  if (!MainFrame())
    return 0;

  UpdateStyleAndLayoutIgnorePendingStylesheets();

  float height = AdjustScrollForAbsoluteZoom(VisibleSize().Height(),
                                             MainFrame()->PageZoomFactor());
  return height - MainFrame()->View()->HorizontalScrollbarHeight() / scale_;
}

double VisualViewport::ScaleForVisualViewport() const {
  return Scale();
}

void VisualViewport::SetScaleAndLocation(float scale,
                                         const FloatPoint& location) {
  if (DidSetScaleOrLocation(scale, location))
    NotifyRootFrameViewport();
}

bool VisualViewport::DidSetScaleOrLocation(float scale,
                                           const FloatPoint& location) {
  if (!MainFrame())
    return false;

  bool values_changed = false;

  if (scale != scale_ && !std::isnan(scale) && !std::isinf(scale)) {
    scale_ = scale;
    values_changed = true;
    GetPage().GetChromeClient().PageScaleFactorChanged();
    EnqueueResizeEvent();
  }

  ScrollOffset clamped_offset = ClampScrollOffset(ToScrollOffset(location));

  // TODO(bokan): If the offset is invalid, we might end up in an infinite
  // recursion as we reenter this function on clamping. It would be cleaner to
  // avoid reentrancy but for now just prevent the stack overflow.
  // crbug.com/702771.
  if (std::isnan(clamped_offset.Width()) ||
      std::isnan(clamped_offset.Height()) ||
      std::isinf(clamped_offset.Width()) || std::isinf(clamped_offset.Height()))
    return false;

  if (clamped_offset != offset_) {
    offset_ = clamped_offset;
    GetScrollAnimator().SetCurrentOffset(offset_);

    // SVG runs with accelerated compositing disabled so no
    // ScrollingCoordinator.
    if (ScrollingCoordinator* coordinator = GetPage().GetScrollingCoordinator())
      coordinator->ScrollableAreaScrollLayerDidChange(this);

    if (!GetPage().GetSettings().GetInertVisualViewport()) {
      if (Document* document = MainFrame()->GetDocument())
        document->EnqueueScrollEventForNode(document);
    }

    EnqueueScrollEvent();

    MainFrame()->View()->DidChangeScrollOffset();
    values_changed = true;
  }

  if (!values_changed)
    return false;

  probe::didChangeViewport(MainFrame());
  MainFrame()->Loader().SaveScrollState();

  ClampToBoundaries();

  return true;
}

bool VisualViewport::MagnifyScaleAroundAnchor(float magnify_delta,
                                              const FloatPoint& anchor) {
  const float old_page_scale = Scale();
  const float new_page_scale =
      GetPage().GetChromeClient().ClampPageScaleFactorToLimits(magnify_delta *
                                                               old_page_scale);
  if (new_page_scale == old_page_scale)
    return false;
  if (!MainFrame() || !MainFrame()->View())
    return false;

  // Keep the center-of-pinch anchor in a stable position over the course
  // of the magnify.
  // TODO(bokan): Looks like we call into setScaleAndLocation with infinity for
  // the location so it seems either old or newPageScale is invalid.
  // crbug.com/702771.
  FloatPoint anchor_at_old_scale = anchor.ScaledBy(1.f / old_page_scale);
  FloatPoint anchor_at_new_scale = anchor.ScaledBy(1.f / new_page_scale);
  FloatSize anchor_delta = anchor_at_old_scale - anchor_at_new_scale;

  // First try to use the anchor's delta to scroll the FrameView.
  FloatSize anchor_delta_unused_by_scroll = anchor_delta;

  // Manually bubble any remaining anchor delta up to the visual viewport.
  FloatPoint new_location(FloatPoint(GetScrollOffset()) +
                          anchor_delta_unused_by_scroll);
  SetScaleAndLocation(new_page_scale, new_location);
  return true;
}

void VisualViewport::CreateLayerTree() {
  if (inner_viewport_scroll_layer_)
    return;

  DCHECK(!overlay_scrollbar_horizontal_ && !overlay_scrollbar_vertical_ &&
         !overscroll_elasticity_layer_ && !page_scale_layer_ &&
         !inner_viewport_container_layer_);

  // FIXME: The root transform layer should only be created on demand.
  root_transform_layer_ = GraphicsLayer::Create(this);
  inner_viewport_container_layer_ = GraphicsLayer::Create(this);
  overscroll_elasticity_layer_ = GraphicsLayer::Create(this);
  page_scale_layer_ = GraphicsLayer::Create(this);
  inner_viewport_scroll_layer_ = GraphicsLayer::Create(this);
  overlay_scrollbar_horizontal_ = GraphicsLayer::Create(this);
  overlay_scrollbar_vertical_ = GraphicsLayer::Create(this);

  ScrollingCoordinator* coordinator = GetPage().GetScrollingCoordinator();
  DCHECK(coordinator);
  coordinator->SetLayerIsContainerForFixedPositionLayers(
      inner_viewport_scroll_layer_.get(), true);

  // Set masks to bounds so the compositor doesn't clobber a manually
  // set inner viewport container layer size.
  inner_viewport_container_layer_->SetMasksToBounds(
      GetPage().GetSettings().GetMainFrameClipsContent());
  inner_viewport_container_layer_->SetSize(FloatSize(size_));

  inner_viewport_scroll_layer_->PlatformLayer()->SetScrollClipLayer(
      inner_viewport_container_layer_->PlatformLayer());
  inner_viewport_scroll_layer_->PlatformLayer()->SetUserScrollable(true, true);
  if (MainFrame()) {
    if (Document* document = MainFrame()->GetDocument()) {
      inner_viewport_scroll_layer_->SetElementId(
          CompositorElementIdFromDOMNodeId(
              DOMNodeIds::IdForNode(document),
              CompositorElementIdNamespace::kViewport));
    }
  }

  root_transform_layer_->AddChild(inner_viewport_container_layer_.get());
  inner_viewport_container_layer_->AddChild(overscroll_elasticity_layer_.get());
  overscroll_elasticity_layer_->AddChild(page_scale_layer_.get());
  page_scale_layer_->AddChild(inner_viewport_scroll_layer_.get());

  // Ensure this class is set as the scroll layer's ScrollableArea.
  coordinator->ScrollableAreaScrollLayerDidChange(this);

  InitializeScrollbars();
}

void VisualViewport::AttachLayerTree(GraphicsLayer* current_layer_tree_root) {
  TRACE_EVENT1("blink", "VisualViewport::attachLayerTree",
               "currentLayerTreeRoot", (bool)current_layer_tree_root);
  if (!current_layer_tree_root) {
    if (inner_viewport_scroll_layer_)
      inner_viewport_scroll_layer_->RemoveAllChildren();
    return;
  }

  if (current_layer_tree_root->Parent() &&
      current_layer_tree_root->Parent() == inner_viewport_scroll_layer_.get())
    return;

  DCHECK(inner_viewport_scroll_layer_);
  inner_viewport_scroll_layer_->RemoveAllChildren();
  inner_viewport_scroll_layer_->AddChild(current_layer_tree_root);
}

void VisualViewport::InitializeScrollbars() {
  // Do nothing if not attached to layer tree yet - will initialize upon attach.
  if (!inner_viewport_container_layer_)
    return;

  if (VisualViewportSuppliesScrollbars() &&
      !GetPage().GetSettings().GetHideScrollbars()) {
    if (!overlay_scrollbar_horizontal_->Parent())
      inner_viewport_container_layer_->AddChild(
          overlay_scrollbar_horizontal_.get());
    if (!overlay_scrollbar_vertical_->Parent())
      inner_viewport_container_layer_->AddChild(
          overlay_scrollbar_vertical_.get());
  } else {
    overlay_scrollbar_horizontal_->RemoveFromParent();
    overlay_scrollbar_vertical_->RemoveFromParent();
  }

  SetupScrollbar(WebScrollbar::kHorizontal);
  SetupScrollbar(WebScrollbar::kVertical);

  // Ensure existing FrameView scrollbars are removed if the visual viewport
  // scrollbars are now supplied, or created if the visual viewport no longer
  // supplies scrollbars.
  LocalFrame* frame = MainFrame();
  if (frame && frame->View())
    frame->View()->VisualViewportScrollbarsChanged();
}

void VisualViewport::SetupScrollbar(WebScrollbar::Orientation orientation) {
  bool is_horizontal = orientation == WebScrollbar::kHorizontal;
  GraphicsLayer* scrollbar_graphics_layer =
      is_horizontal ? overlay_scrollbar_horizontal_.get()
                    : overlay_scrollbar_vertical_.get();
  std::unique_ptr<WebScrollbarLayer>& web_scrollbar_layer =
      is_horizontal ? web_overlay_scrollbar_horizontal_
                    : web_overlay_scrollbar_vertical_;

  ScrollbarThemeOverlay& theme = ScrollbarThemeOverlay::MobileTheme();
  int thumb_thickness = theme.ThumbThickness();
  int scrollbar_thickness = theme.ScrollbarThickness(kRegularScrollbar);
  int scrollbar_margin = theme.ScrollbarMargin();

  if (!web_scrollbar_layer) {
    ScrollingCoordinator* coordinator = GetPage().GetScrollingCoordinator();
    DCHECK(coordinator);
    ScrollbarOrientation webcore_orientation =
        is_horizontal ? kHorizontalScrollbar : kVerticalScrollbar;
    web_scrollbar_layer = coordinator->CreateSolidColorScrollbarLayer(
        webcore_orientation, thumb_thickness, scrollbar_margin, false);

    // The compositor will control the scrollbar's visibility. Set to invisible
    // by default so scrollbars don't show up in layout tests.
    web_scrollbar_layer->Layer()->SetOpacity(0);
    scrollbar_graphics_layer->SetContentsToPlatformLayer(
        web_scrollbar_layer->Layer());
    scrollbar_graphics_layer->SetDrawsContent(false);
  }

  int x_position = is_horizontal
                       ? 0
                       : inner_viewport_container_layer_->Size().Width() -
                             scrollbar_thickness;
  int y_position = is_horizontal
                       ? inner_viewport_container_layer_->Size().Height() -
                             scrollbar_thickness
                       : 0;
  int width = is_horizontal ? inner_viewport_container_layer_->Size().Width() -
                                  scrollbar_thickness
                            : scrollbar_thickness;
  int height = is_horizontal
                   ? scrollbar_thickness
                   : inner_viewport_container_layer_->Size().Height() -
                         scrollbar_thickness;

  // Use the GraphicsLayer to position the scrollbars.
  scrollbar_graphics_layer->SetPosition(IntPoint(x_position, y_position));
  scrollbar_graphics_layer->SetSize(FloatSize(width, height));
  scrollbar_graphics_layer->SetContentsRect(IntRect(0, 0, width, height));
}

void VisualViewport::SetScrollLayerOnScrollbars(WebLayer* scroll_layer) const {
  // TODO(bokan): This is currently done while registering viewport layers
  // with the compositor but could it actually be done earlier, like in
  // setupScrollbars? Then we wouldn't need this method.
  web_overlay_scrollbar_horizontal_->SetScrollLayer(scroll_layer);
  web_overlay_scrollbar_vertical_->SetScrollLayer(scroll_layer);
}

bool VisualViewport::VisualViewportSuppliesScrollbars() const {
  return GetPage().GetSettings().GetViewportEnabled();
}

bool VisualViewport::ScrollAnimatorEnabled() const {
  return GetPage().GetSettings().GetScrollAnimatorEnabled();
}

PlatformChromeClient* VisualViewport::GetChromeClient() const {
  return &GetPage().GetChromeClient();
}

bool VisualViewport::ShouldUseIntegerScrollOffset() const {
  LocalFrame* frame = MainFrame();
  if (frame && frame->GetSettings() &&
      !frame->GetSettings()->GetPreferCompositingToLCDTextEnabled())
    return true;

  return ScrollableArea::ShouldUseIntegerScrollOffset();
}

void VisualViewport::SetScrollOffset(const ScrollOffset& offset,
                                     ScrollType scroll_type,
                                     ScrollBehavior scroll_behavior) {
  // We clamp the offset here, because the ScrollAnimator may otherwise be
  // set to a non-clamped offset by ScrollableArea::setScrollOffset,
  // which may lead to incorrect scrolling behavior in RootFrameViewport down
  // the line.
  // TODO(eseckler): Solve this instead by ensuring that ScrollableArea and
  // ScrollAnimator are kept in sync. This requires that ScrollableArea always
  // stores fractional offsets and that truncation happens elsewhere, see
  // crbug.com/626315.
  ScrollOffset new_scroll_offset = ClampScrollOffset(offset);
  ScrollableArea::SetScrollOffset(new_scroll_offset, scroll_type,
                                  scroll_behavior);
}

int VisualViewport::ScrollSize(ScrollbarOrientation orientation) const {
  IntSize scroll_dimensions =
      MaximumScrollOffsetInt() - MinimumScrollOffsetInt();
  return (orientation == kHorizontalScrollbar) ? scroll_dimensions.Width()
                                               : scroll_dimensions.Height();
}

IntSize VisualViewport::MinimumScrollOffsetInt() const {
  return IntSize();
}

IntSize VisualViewport::MaximumScrollOffsetInt() const {
  return FlooredIntSize(MaximumScrollOffset());
}

ScrollOffset VisualViewport::MaximumScrollOffset() const {
  if (!MainFrame())
    return ScrollOffset();

  // TODO(bokan): We probably shouldn't be storing the bounds in a float.
  // crbug.com/470718.
  FloatSize frame_view_size(ContentsSize());

  if (browser_controls_adjustment_) {
    float min_scale =
        GetPage().GetPageScaleConstraintsSet().FinalConstraints().minimum_scale;
    frame_view_size.Expand(0, browser_controls_adjustment_ / min_scale);
  }

  frame_view_size.Scale(scale_);
  frame_view_size = FloatSize(FlooredIntSize(frame_view_size));

  FloatSize viewport_size(size_);
  viewport_size.Expand(0, ceilf(browser_controls_adjustment_));

  FloatSize max_position = frame_view_size - viewport_size;
  max_position.Scale(1 / scale_);
  return ScrollOffset(max_position);
}

IntPoint VisualViewport::ClampDocumentOffsetAtScale(const IntPoint& offset,
                                                    float scale) {
  if (!MainFrame() || !MainFrame()->View())
    return IntPoint();

  FrameView* view = MainFrame()->View();

  FloatSize scaled_size(size_);
  scaled_size.Scale(1 / scale);

  IntSize visual_viewport_max =
      FlooredIntSize(FloatSize(ContentsSize()) - scaled_size);
  IntSize max = view->MaximumScrollOffsetInt() + visual_viewport_max;
  IntSize min =
      view->MinimumScrollOffsetInt();  // VisualViewportMin should be (0, 0)

  IntSize clamped = ToIntSize(offset);
  clamped = clamped.ShrunkTo(max);
  clamped = clamped.ExpandedTo(min);
  return IntPoint(clamped);
}

void VisualViewport::SetBrowserControlsAdjustment(float adjustment) {
  browser_controls_adjustment_ = adjustment;
}

float VisualViewport::BrowserControlsAdjustment() const {
  return browser_controls_adjustment_;
}

IntRect VisualViewport::ScrollableAreaBoundingBox() const {
  // This method should return the bounding box in the top-level FrameView's
  // coordinate space; however, VisualViewport technically isn't a child of any
  // Frames.  Nonetheless, the VisualViewport always occupies the entire main
  // frame so just return that.
  LocalFrame* frame = MainFrame();

  if (!frame || !frame->View())
    return IntRect();

  return frame->View()->FrameRect();
}

IntSize VisualViewport::ContentsSize() const {
  LocalFrame* frame = MainFrame();

  if (!frame || !frame->View())
    return IntSize();

  // TODO(bokan): This should be the layout viewport rather than main FrameView.
  return frame->View()->VisibleContentRect(kIncludeScrollbars).Size();
}

IntRect VisualViewport::VisibleContentRect(
    IncludeScrollbarsInRect scrollbar_inclusion) const {
  // TODO(ymalik): We're losing precision here and below. visibleRect should
  // be replaced with visibleContentRect.
  IntRect rect = IntRect(VisibleRect());
  if (scrollbar_inclusion == kExcludeScrollbars) {
    RootFrameViewport* root_frame_viewport =
        MainFrame()->View()->GetRootFrameViewport();
    DCHECK(root_frame_viewport);
    rect.Contract(root_frame_viewport->VerticalScrollbarWidth() / scale_,
                  root_frame_viewport->HorizontalScrollbarHeight() / scale_);
  }
  return rect;
}

RefPtr<WebTaskRunner> VisualViewport::GetTimerTaskRunner() const {
  return TaskRunnerHelper::Get(TaskType::kUnspecedTimer, MainFrame());
}

void VisualViewport::UpdateScrollOffset(const ScrollOffset& position,
                                        ScrollType scroll_type) {
  if (!DidSetScaleOrLocation(scale_, FloatPoint(position)))
    return;
  if (IsExplicitScrollType(scroll_type)) {
    NotifyRootFrameViewport();
    if (scroll_type != kCompositorScroll && LayerForScrolling())
      LayerForScrolling()->PlatformLayer()->ShowScrollbars();
  }
}

GraphicsLayer* VisualViewport::LayerForContainer() const {
  return inner_viewport_container_layer_.get();
}

GraphicsLayer* VisualViewport::LayerForScrolling() const {
  return inner_viewport_scroll_layer_.get();
}

GraphicsLayer* VisualViewport::LayerForHorizontalScrollbar() const {
  return overlay_scrollbar_horizontal_.get();
}

GraphicsLayer* VisualViewport::LayerForVerticalScrollbar() const {
  return overlay_scrollbar_vertical_.get();
}

IntRect VisualViewport::ComputeInterestRect(const GraphicsLayer*,
                                            const IntRect&) const {
  return IntRect();
}

void VisualViewport::PaintContents(const GraphicsLayer*,
                                   GraphicsContext&,
                                   GraphicsLayerPaintingPhase,
                                   const IntRect&) const {}

LocalFrame* VisualViewport::MainFrame() const {
  return GetPage().MainFrame() && GetPage().MainFrame()->IsLocalFrame()
             ? GetPage().DeprecatedLocalMainFrame()
             : 0;
}

bool VisualViewport::ScheduleAnimation() {
  if (PlatformChromeClient* client = GetChromeClient()) {
    client->ScheduleAnimation(MainFrame()->View());
    return true;
  }
  return false;
}

void VisualViewport::ClampToBoundaries() {
  SetLocation(FloatPoint(offset_));
}

FloatRect VisualViewport::ViewportToRootFrame(
    const FloatRect& rect_in_viewport) const {
  FloatRect rect_in_root_frame = rect_in_viewport;
  rect_in_root_frame.Scale(1 / Scale());
  rect_in_root_frame.Move(GetScrollOffset());
  return rect_in_root_frame;
}

IntRect VisualViewport::ViewportToRootFrame(
    const IntRect& rect_in_viewport) const {
  // FIXME: How to snap to pixels?
  return EnclosingIntRect(ViewportToRootFrame(FloatRect(rect_in_viewport)));
}

FloatRect VisualViewport::RootFrameToViewport(
    const FloatRect& rect_in_root_frame) const {
  FloatRect rect_in_viewport = rect_in_root_frame;
  rect_in_viewport.Move(-GetScrollOffset());
  rect_in_viewport.Scale(Scale());
  return rect_in_viewport;
}

IntRect VisualViewport::RootFrameToViewport(
    const IntRect& rect_in_root_frame) const {
  // FIXME: How to snap to pixels?
  return EnclosingIntRect(RootFrameToViewport(FloatRect(rect_in_root_frame)));
}

FloatPoint VisualViewport::ViewportToRootFrame(
    const FloatPoint& point_in_viewport) const {
  FloatPoint point_in_root_frame = point_in_viewport;
  point_in_root_frame.Scale(1 / Scale(), 1 / Scale());
  point_in_root_frame.Move(GetScrollOffset());
  return point_in_root_frame;
}

FloatPoint VisualViewport::RootFrameToViewport(
    const FloatPoint& point_in_root_frame) const {
  FloatPoint point_in_viewport = point_in_root_frame;
  point_in_viewport.Move(-GetScrollOffset());
  point_in_viewport.Scale(Scale(), Scale());
  return point_in_viewport;
}

IntPoint VisualViewport::ViewportToRootFrame(
    const IntPoint& point_in_viewport) const {
  // FIXME: How to snap to pixels?
  return FlooredIntPoint(
      FloatPoint(ViewportToRootFrame(FloatPoint(point_in_viewport))));
}

IntPoint VisualViewport::RootFrameToViewport(
    const IntPoint& point_in_root_frame) const {
  // FIXME: How to snap to pixels?
  return FlooredIntPoint(
      FloatPoint(RootFrameToViewport(FloatPoint(point_in_root_frame))));
}

void VisualViewport::StartTrackingPinchStats() {
  if (!MainFrame())
    return;

  Document* document = MainFrame()->GetDocument();
  if (!document)
    return;

  if (!document->Url().ProtocolIsInHTTPFamily())
    return;

  track_pinch_zoom_stats_for_page_ = !ShouldDisableDesktopWorkarounds();
}

void VisualViewport::UserDidChangeScale() {
  if (!track_pinch_zoom_stats_for_page_)
    return;

  max_page_scale_ = std::max(max_page_scale_, scale_);
}

void VisualViewport::SendUMAMetrics() {
  if (track_pinch_zoom_stats_for_page_) {
    bool did_scale = max_page_scale_ > 0;

    DEFINE_STATIC_LOCAL(EnumerationHistogram, did_scale_histogram,
                        ("Viewport.DidScalePage", 2));
    did_scale_histogram.Count(did_scale ? 1 : 0);

    if (did_scale) {
      int zoom_percentage = floor(max_page_scale_ * 100);

      // See the PageScaleFactor enumeration in histograms.xml for the bucket
      // ranges.
      int bucket = floor(zoom_percentage / 25.f);

      DEFINE_STATIC_LOCAL(EnumerationHistogram, max_scale_histogram,
                          ("Viewport.MaxPageScale", 21));
      max_scale_histogram.Count(bucket);
    }
  }

  max_page_scale_ = -1;
  track_pinch_zoom_stats_for_page_ = false;
}

bool VisualViewport::ShouldDisableDesktopWorkarounds() const {
  if (!MainFrame() || !MainFrame()->View())
    return false;

  if (!MainFrame()->GetSettings()->GetViewportEnabled())
    return false;

  // A document is considered adapted to small screen UAs if one of these holds:
  // 1. The author specified viewport has a constrained width that is equal to
  //    the initial viewport width.
  // 2. The author has disabled viewport zoom.
  const PageScaleConstraints& constraints =
      GetPage().GetPageScaleConstraintsSet().PageDefinedConstraints();

  return MainFrame()->View()->GetLayoutSize().Width() == size_.Width() ||
         (constraints.minimum_scale == constraints.maximum_scale &&
          constraints.minimum_scale != -1);
}

CompositorAnimationHost* VisualViewport::GetCompositorAnimationHost() const {
  DCHECK(GetPage().MainFrame()->IsLocalFrame());
  ScrollingCoordinator* c = GetPage().GetScrollingCoordinator();
  return c ? c->GetCompositorAnimationHost() : nullptr;
}

CompositorAnimationTimeline* VisualViewport::GetCompositorAnimationTimeline()
    const {
  DCHECK(GetPage().MainFrame()->IsLocalFrame());
  ScrollingCoordinator* c = GetPage().GetScrollingCoordinator();
  return c ? c->GetCompositorAnimationTimeline() : nullptr;
}

void VisualViewport::NotifyRootFrameViewport() const {
  if (!MainFrame() || !MainFrame()->View())
    return;

  RootFrameViewport* root_frame_viewport =
      MainFrame()->View()->GetRootFrameViewport();

  if (!root_frame_viewport)
    return;

  root_frame_viewport->DidUpdateVisualViewport();
}

String VisualViewport::DebugName(const GraphicsLayer* graphics_layer) const {
  String name;
  if (graphics_layer == inner_viewport_container_layer_.get()) {
    name = "Inner Viewport Container Layer";
  } else if (graphics_layer == overscroll_elasticity_layer_.get()) {
    name = "Overscroll Elasticity Layer";
  } else if (graphics_layer == page_scale_layer_.get()) {
    name = "Page Scale Layer";
  } else if (graphics_layer == inner_viewport_scroll_layer_.get()) {
    name = "Inner Viewport Scroll Layer";
  } else if (graphics_layer == overlay_scrollbar_horizontal_.get()) {
    name = "Overlay Scrollbar Horizontal Layer";
  } else if (graphics_layer == overlay_scrollbar_vertical_.get()) {
    name = "Overlay Scrollbar Vertical Layer";
  } else if (graphics_layer == root_transform_layer_.get()) {
    name = "Root Transform Layer";
  } else {
    NOTREACHED();
  }

  return name;
}

}  // namespace blink