// Copyright 2017 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 "components/exo/surface_tree_host.h"

#include <algorithm>

#include "base/macros.h"
#include "cc/trees/layer_tree_frame_sink.h"
#include "components/exo/layer_tree_frame_sink_holder.h"
#include "components/exo/surface.h"
#include "components/exo/wm_helper.h"
#include "components/viz/common/quads/compositor_frame.h"
#include "gpu/command_buffer/client/gles2_interface.h"
#include "services/ui/public/interfaces/window_tree_constants.mojom.h"
#include "ui/aura/env.h"
#include "ui/aura/window.h"
#include "ui/aura/window_delegate.h"
#include "ui/aura/window_event_dispatcher.h"
#include "ui/aura/window_occlusion_tracker.h"
#include "ui/aura/window_targeter.h"
#include "ui/aura/window_tree_host.h"
#include "ui/base/cursor/cursor.h"
#include "ui/display/display.h"
#include "ui/display/screen.h"
#include "ui/gfx/geometry/dip_util.h"
#include "ui/gfx/path.h"

namespace exo {

namespace {

class CustomWindowTargeter : public aura::WindowTargeter {
 public:
  explicit CustomWindowTargeter(SurfaceTreeHost* surface_tree_host)
      : surface_tree_host_(surface_tree_host) {}
  ~CustomWindowTargeter() override = default;

  // Overridden from aura::WindowTargeter:
  bool EventLocationInsideBounds(aura::Window* window,
                                 const ui::LocatedEvent& event) const override {
    if (window != surface_tree_host_->host_window())
      return aura::WindowTargeter::EventLocationInsideBounds(window, event);

    Surface* surface = surface_tree_host_->root_surface();
    if (!surface)
      return false;

    gfx::Point local_point = event.location();

    if (window->parent())
      aura::Window::ConvertPointToTarget(window->parent(), window,
                                         &local_point);
    aura::Window::ConvertPointToTarget(window, surface->window(), &local_point);
    return surface->HitTest(local_point);
  }

  ui::EventTarget* FindTargetForEvent(ui::EventTarget* root,
                                      ui::Event* event) override {
    aura::Window* window = static_cast<aura::Window*>(root);
    if (window != surface_tree_host_->host_window())
      return aura::WindowTargeter::FindTargetForEvent(root, event);
    ui::EventTarget* target =
        aura::WindowTargeter::FindTargetForEvent(root, event);
    // Do not accept events in SurfaceTreeHost window.
    return target != root ? target : nullptr;
  }

 private:
  SurfaceTreeHost* const surface_tree_host_;

  DISALLOW_COPY_AND_ASSIGN(CustomWindowTargeter);
};

}  // namespace

////////////////////////////////////////////////////////////////////////////////
// SurfaceTreeHost, public:

SurfaceTreeHost::SurfaceTreeHost(const std::string& window_name)
    : host_window_(std::make_unique<aura::Window>(nullptr)) {
  host_window_->SetType(aura::client::WINDOW_TYPE_CONTROL);
  host_window_->SetName(window_name);
  host_window_->Init(ui::LAYER_SOLID_COLOR);
  host_window_->set_owned_by_parent(false);
  // The host window is a container of surface tree. It doesn't handle pointer
  // events.
  host_window_->SetEventTargetingPolicy(
      ui::mojom::EventTargetingPolicy::DESCENDANTS_ONLY);
  host_window_->SetEventTargeter(std::make_unique<CustomWindowTargeter>(this));
  layer_tree_frame_sink_holder_ = std::make_unique<LayerTreeFrameSinkHolder>(
      this, host_window_->CreateLayerTreeFrameSink());
  aura::Env::GetInstance()->context_factory()->AddObserver(this);
}

SurfaceTreeHost::~SurfaceTreeHost() {
  aura::Env::GetInstance()->context_factory()->RemoveObserver(this);
  SetRootSurface(nullptr);
  LayerTreeFrameSinkHolder::DeleteWhenLastResourceHasBeenReclaimed(
      std::move(layer_tree_frame_sink_holder_));
}

void SurfaceTreeHost::SetRootSurface(Surface* root_surface) {
  if (root_surface == root_surface_)
    return;

  // This method applies multiple changes to the window tree. Use
  // ScopedPauseOcclusionTracking to ensure that occlusion isn't recomputed
  // before all changes have been applied.
  aura::WindowOcclusionTracker::ScopedPauseOcclusionTracking pause_occlusion;

  if (root_surface_) {
    root_surface_->window()->Hide();
    host_window_->RemoveChild(root_surface_->window());
    host_window_->SetBounds(
        gfx::Rect(host_window_->bounds().origin(), gfx::Size()));
    root_surface_->SetSurfaceDelegate(nullptr);
    // Force recreating resources when the surface is added to a tree again.
    root_surface_->SurfaceHierarchyResourcesLost();
    root_surface_ = nullptr;

    active_frame_callbacks_.splice(active_frame_callbacks_.end(),
                                   frame_callbacks_);
    // Call all frame callbacks with a null frame time to indicate that they
    // have been cancelled.
    while (!active_frame_callbacks_.empty()) {
      active_frame_callbacks_.front().Run(base::TimeTicks());
      active_frame_callbacks_.pop_front();
    }

    DCHECK(presentation_callbacks_.empty());
    for (auto entry : active_presentation_callbacks_) {
      while (!entry.second.empty()) {
        entry.second.front().Run(base::TimeTicks(), base::TimeDelta(), 0);
        entry.second.pop_front();
      }
    }
    active_presentation_callbacks_.clear();
  }

  if (root_surface) {
    root_surface_ = root_surface;
    root_surface_->SetSurfaceDelegate(this);
    host_window_->AddChild(root_surface_->window());
    UpdateHostWindowBounds();
    root_surface_->window()->Show();
  }
}

bool SurfaceTreeHost::HasHitTestRegion() const {
  return root_surface_ && root_surface_->HasHitTestRegion();
}

void SurfaceTreeHost::GetHitTestMask(gfx::Path* mask) const {
  if (root_surface_)
    root_surface_->GetHitTestMask(mask);
}

void SurfaceTreeHost::DidReceiveCompositorFrameAck() {
  active_frame_callbacks_.splice(active_frame_callbacks_.end(),
                                 frame_callbacks_);
  UpdateNeedsBeginFrame();
}

void SurfaceTreeHost::DidPresentCompositorFrame(uint32_t presentation_token,
                                                base::TimeTicks time,
                                                base::TimeDelta refresh,
                                                uint32_t flags) {
  auto it = active_presentation_callbacks_.find(presentation_token);
  DCHECK(it != active_presentation_callbacks_.end());
  for (auto callback : it->second)
    callback.Run(time, refresh, flags);
  active_presentation_callbacks_.erase(it);
}

void SurfaceTreeHost::DidDiscardCompositorFrame(uint32_t presentation_token) {
  DidPresentCompositorFrame(presentation_token, base::TimeTicks(),
                            base::TimeDelta(), 0);
}

void SurfaceTreeHost::SetBeginFrameSource(
    viz::BeginFrameSource* begin_frame_source) {
  if (needs_begin_frame_) {
    DCHECK(begin_frame_source_);
    begin_frame_source_->RemoveObserver(this);
    needs_begin_frame_ = false;
  }
  begin_frame_source_ = begin_frame_source;
  UpdateNeedsBeginFrame();
}

void SurfaceTreeHost::UpdateNeedsBeginFrame() {
  if (!begin_frame_source_)
    return;
  bool needs_begin_frame = !active_frame_callbacks_.empty();
  if (needs_begin_frame == needs_begin_frame_)
    return;
  needs_begin_frame_ = needs_begin_frame;
  if (needs_begin_frame_)
    begin_frame_source_->AddObserver(this);
  else
    begin_frame_source_->RemoveObserver(this);
}

////////////////////////////////////////////////////////////////////////////////
// SurfaceDelegate overrides:

void SurfaceTreeHost::OnSurfaceCommit() {
  DCHECK(presentation_callbacks_.empty());
  root_surface_->CommitSurfaceHierarchy(false);
  UpdateHostWindowBounds();
}

bool SurfaceTreeHost::IsSurfaceSynchronized() const {
  // To host a surface tree, the root surface has to be desynchronized.
  DCHECK(root_surface_);
  return false;
}

bool SurfaceTreeHost::IsInputEnabled(Surface*) const {
  return true;
}

////////////////////////////////////////////////////////////////////////////////
// cc::BeginFrameObserverBase overrides:

bool SurfaceTreeHost::OnBeginFrameDerivedImpl(const viz::BeginFrameArgs& args) {
  current_begin_frame_ack_ =
      viz::BeginFrameAck(args.source_id, args.sequence_number, false);

  if (!frame_callbacks_.empty()) {
    // In this case, the begin frame arrives just before
    // |DidReceivedCompositorFrameAck()|, we need more begin frames to run
    // |frame_callbacks_| which will be moved to |active_frame_callbacks_| by
    // |DidReceivedCompositorFrameAck()| shortly.
    layer_tree_frame_sink_holder_->DidNotProduceFrame(current_begin_frame_ack_);
    current_begin_frame_ack_.sequence_number =
        viz::BeginFrameArgs::kInvalidFrameNumber;
    begin_frame_source_->DidFinishFrame(this);
  }

  while (!active_frame_callbacks_.empty()) {
    active_frame_callbacks_.front().Run(args.frame_time);
    active_frame_callbacks_.pop_front();
  }
  return true;
}

////////////////////////////////////////////////////////////////////////////////
// ui::ContextFactoryObserver overrides:

void SurfaceTreeHost::OnLostResources() {
  if (!host_window_->GetSurfaceId().is_valid() || !root_surface_)
    return;
  root_surface_->SurfaceHierarchyResourcesLost();
  SubmitCompositorFrame();
}

////////////////////////////////////////////////////////////////////////////////
// SurfaceTreeHost, protected:

void SurfaceTreeHost::SubmitCompositorFrame() {
  DCHECK(root_surface_);
  viz::CompositorFrame frame;
  // If we commit while we don't have an active BeginFrame, we acknowledge a
  // manual one.
  if (current_begin_frame_ack_.sequence_number ==
      viz::BeginFrameArgs::kInvalidFrameNumber) {
    current_begin_frame_ack_ = viz::BeginFrameAck::CreateManualAckWithDamage();
  } else {
    current_begin_frame_ack_.has_damage = true;
  }
  frame.metadata.begin_frame_ack = current_begin_frame_ack_;
  root_surface_->AppendSurfaceHierarchyCallbacks(&frame_callbacks_,
                                                 &presentation_callbacks_);
  if (!presentation_callbacks_.empty()) {
    // If overflow happens, we increase it again.
    if (!++presentation_token_)
      ++presentation_token_;
    frame.metadata.presentation_token = presentation_token_;
    DCHECK_EQ(active_presentation_callbacks_.count(presentation_token_), 0u);
    active_presentation_callbacks_[presentation_token_] =
        std::move(presentation_callbacks_);
  }
  frame.render_pass_list.push_back(viz::RenderPass::Create());
  const std::unique_ptr<viz::RenderPass>& render_pass =
      frame.render_pass_list.back();
  const int kRenderPassId = 1;
  render_pass->SetNew(kRenderPassId, gfx::Rect(), gfx::Rect(),
                      gfx::Transform());
  float device_scale_factor = host_window()->layer()->device_scale_factor();
  frame.metadata.device_scale_factor = device_scale_factor;
  root_surface_->AppendSurfaceHierarchyContentsToFrame(
      root_surface_origin_, device_scale_factor,
      layer_tree_frame_sink_holder_.get(), &frame);

  if (WMHelper::GetInstance()->AreVerifiedSyncTokensNeeded()) {
    std::vector<GLbyte*> sync_tokens;
    for (auto& resource : frame.resource_list)
      sync_tokens.push_back(resource.mailbox_holder.sync_token.GetData());
    ui::ContextFactory* context_factory =
        aura::Env::GetInstance()->context_factory();
    gpu::gles2::GLES2Interface* gles2 =
        context_factory->SharedMainThreadContextProvider()->ContextGL();
    gles2->VerifySyncTokensCHROMIUM(sync_tokens.data(), sync_tokens.size());
  }

  layer_tree_frame_sink_holder_->SubmitCompositorFrame(std::move(frame));

  if (current_begin_frame_ack_.sequence_number !=
      viz::BeginFrameArgs::kInvalidFrameNumber) {
    if (!current_begin_frame_ack_.has_damage) {
      layer_tree_frame_sink_holder_->DidNotProduceFrame(
          current_begin_frame_ack_);
    }
    current_begin_frame_ack_.sequence_number =
        viz::BeginFrameArgs::kInvalidFrameNumber;
    if (begin_frame_source_)
      begin_frame_source_->DidFinishFrame(this);
  }
}

////////////////////////////////////////////////////////////////////////////////
// SurfaceTreeHost, private:

void SurfaceTreeHost::UpdateHostWindowBounds() {
  // This method applies multiple changes to the window tree. Use
  // ScopedPauseOcclusionTracking to ensure that occlusion isn't recomputed
  // before all changes have been applied.
  aura::WindowOcclusionTracker::ScopedPauseOcclusionTracking pause_occlusion;

  gfx::Rect bounds = root_surface_->surface_hierarchy_content_bounds();
  host_window_->SetBounds(
      gfx::Rect(host_window_->bounds().origin(), bounds.size()));
  const bool fills_bounds_opaquely =
      bounds.size() == root_surface_->content_size() &&
      root_surface_->FillsBoundsOpaquely();
  host_window_->SetTransparent(!fills_bounds_opaquely);

  root_surface_origin_ = gfx::Point() - bounds.OffsetFromOrigin();
  root_surface_->window()->SetBounds(gfx::Rect(
      root_surface_origin_, root_surface_->window()->bounds().size()));
}

}  // namespace exo