// Copyright 2018 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include <optional>

#include "base/memory/raw_ptr.h"
#include "content/browser/media/capture/mouse_cursor_overlay_controller.h"
#include "third_party/skia/include/core/SkBitmap.h"
#include "ui/aura/client/cursor_shape_client.h"
#include "ui/aura/window.h"
#include "ui/aura/window_tree_host.h"
#include "ui/base/cursor/cursor.h"
#include "ui/base/cursor/mojom/cursor_type.mojom-shared.h"
#include "ui/events/event.h"
#include "ui/events/event_handler.h"
#include "ui/gfx/geometry/point.h"
#include "ui/wm/public/activation_client.h"

namespace content {

class MouseCursorOverlayController::Observer final
    : public ui::EventHandler,
      public aura::WindowObserver {
 public:
  explicit Observer(MouseCursorOverlayController* controller,
                    aura::Window* window)
      : controller_(controller), window_(window) {
    DCHECK(controller_);
    DCHECK(window_);
    controller_->OnMouseHasGoneIdle();
    window_->AddObserver(this);
    window_->AddPreTargetHandler(this);
  }

  Observer(const Observer&) = delete;
  Observer& operator=(const Observer&) = delete;

  ~Observer() final {
    if (window_) {
      OnWindowDestroying(window_);
    }
  }

  void StopTracking() {
    if (window_) {
      window_->RemovePreTargetHandler(this);
      controller_->OnMouseHasGoneIdle();
    }
  }

  static aura::Window* GetTargetWindow(
      const std::unique_ptr<Observer>& observer) {
    if (observer) {
      return observer->window_;
    }
    return nullptr;
  }

 private:
  bool IsWindowActive() const {
    if (window_) {
      if (auto* root_window = window_->GetRootWindow()) {
        if (window_ == root_window) {
          return true;
        }
        if (auto* client = wm::GetActivationClient(root_window)) {
          if (auto* active_window = client->GetActiveWindow()) {
            return active_window->Contains(window_);
          }
        }
      }
    }
    return false;
  }

  gfx::PointF AsLocationInWindow(const ui::Event& event) const {
    gfx::PointF location = event.AsLocatedEvent()->location_f();
    if (event.target() != window_) {
      aura::Window::ConvertPointToTarget(
          static_cast<aura::Window*>(event.target()), window_, &location);
    }
    return location;
  }

  gfx::Point CoordinatesForMouseEvent(const ui::Event& event) const {
    if (!IsWindowActive() || event.type() == ui::EventType::kMouseExited) {
      return kOutsideSurface;
    }
    gfx::PointF location = AsLocationInWindow(event);
    int x = std::round(location.x());
    int y = std::round(location.y());

    // When performing a drag on some platforms, it's possible to
    // trigger mouse events with coordinates outside the surface, so
    // make sure we don't transmit such coordinates.
    const gfx::Size& window_size = window_->bounds().size();
    if (x < 0 || y < 0 || x >= window_size.width() ||
        y >= window_size.height()) {
      return kOutsideSurface;
    }

    return gfx::Point(x, y);
  }

  // ui::EventHandler overrides.
  void OnEvent(ui::Event* event) final {
    switch (event->type()) {
      case ui::EventType::kMouseDragged:
      case ui::EventType::kMouseMoved:
      case ui::EventType::kMouseEntered:
      case ui::EventType::kMouseExited:
      case ui::EventType::kTouchMoved:
        if (IsWindowActive()) {
          controller_->OnMouseMoved(AsLocationInWindow(*event));
        }
        if (controller_->ShouldSendMouseEvents()) {
          controller_->OnMouseCoordinatesUpdated(
              CoordinatesForMouseEvent(*event));
        }
        break;
      case ui::EventType::kMousePressed:
      case ui::EventType::kMouseReleased:
      case ui::EventType::kMousewheel:
      case ui::EventType::kTouchPressed:
      case ui::EventType::kTouchReleased: {
        controller_->OnMouseClicked(AsLocationInWindow(*event));
        break;
      }

      default:
        return;
    }
  }

  // aura::WindowObserver overrides.
  void OnWindowDestroying(aura::Window* window) final {
    DCHECK_EQ(window_, window);
    StopTracking();
    window_->RemoveObserver(this);
    window_ = nullptr;
  }

  const raw_ptr<MouseCursorOverlayController> controller_;
  raw_ptr<aura::Window> window_;
};

MouseCursorOverlayController::MouseCursorOverlayController()
    // base::Unretained(this) is safe because we own mouse_activity_ended_timer_
    // and its destructor calls TimerBase::AbandonScheduledTask().
    : mouse_activity_ended_timer_(
          FROM_HERE,
          kIdleTimeout,
          base::BindRepeating(&MouseCursorOverlayController::OnMouseHasGoneIdle,
                              base::Unretained(this))),
      mouse_move_behavior_atomic_(kNotMoving) {
  // MouseCursorOverlayController can be constructed on any thread, but
  // thereafter must be used according to class-level comments.
  DETACH_FROM_SEQUENCE(ui_sequence_checker_);
}

MouseCursorOverlayController::~MouseCursorOverlayController() {
  DCHECK_CALLED_ON_VALID_SEQUENCE(ui_sequence_checker_);

  observer_.reset();
  Stop();
}

void MouseCursorOverlayController::SetTargetView(aura::Window* window) {
  DCHECK_CALLED_ON_VALID_SEQUENCE(ui_sequence_checker_);

  observer_.reset();
  if (window) {
    observer_ = std::make_unique<Observer>(this, window);
  }
}

gfx::NativeCursor MouseCursorOverlayController::GetCurrentCursorOrDefault()
    const {
  DCHECK_CALLED_ON_VALID_SEQUENCE(ui_sequence_checker_);

  if (auto* window = Observer::GetTargetWindow(observer_)) {
    if (auto* host = window->GetHost()) {
      gfx::NativeCursor cursor = host->last_cursor();
      if (cursor != ui::mojom::CursorType::kNull)
        return cursor;
    }
  }

  return ui::mojom::CursorType::kPointer;
}

gfx::RectF MouseCursorOverlayController::ComputeRelativeBoundsForOverlay(
    const gfx::NativeCursor& cursor,
    const gfx::PointF& location) const {
  DCHECK_CALLED_ON_VALID_SEQUENCE(ui_sequence_checker_);

  auto* window = Observer::GetTargetWindow(observer_);
  if (!window)
    return gfx::RectF();

  const gfx::Size& window_size = window->bounds().size();
  std::optional<ui::CursorData> cursor_data =
      aura::client::GetCursorShapeClient().GetCursorData(cursor);
  if (window_size.IsEmpty() || !window->GetRootWindow() || !cursor_data)
    return gfx::RectF();

  const SkBitmap& bitmap = cursor_data->bitmaps[0];
  const float scale_factor = cursor_data->scale_factor;

  // Compute the cursor size in terms of DIP coordinates.
  const gfx::SizeF size = gfx::ScaleSize(
      gfx::SizeF(bitmap.width(), bitmap.height()), 1.0f / scale_factor);

  // Compute the hotspot in terms of DIP coordinates.
  const gfx::PointF hotspot =
      gfx::ScalePoint(gfx::PointF(cursor_data->hotspot), 1.0f / scale_factor);

  // Finally, put it all together: Scale the absolute bounds of the
  // overlay by the window size to produce relative coordinates.
  return gfx::ScaleRect(gfx::RectF(location - hotspot.OffsetFromOrigin(), size),
                        1.0f / window_size.width(),
                        1.0f / window_size.height());
}

void MouseCursorOverlayController::DisconnectFromToolkitForTesting() {
  DCHECK_CALLED_ON_VALID_SEQUENCE(ui_sequence_checker_);

  observer_->StopTracking();

  // Note: Not overriding the mouse cursor since the default is already
  // ui::mojom::CursorType::kPointer, which provides the tests a bitmap they can
  // work with.
}

// static
SkBitmap MouseCursorOverlayController::GetCursorImage(
    const gfx::NativeCursor& cursor) {
  std::optional<ui::CursorData> cursor_data =
      aura::client::GetCursorShapeClient().GetCursorData(cursor);
  if (!cursor_data)
    return SkBitmap();

  return cursor_data->bitmaps[0];
}

}  // namespace content