/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */

/* vim: set ts=8 sts=2 et sw=2 tw=80: */

/* This Source Code Form is subject to the terms of the Mozilla Public

 * License, v. 2.0. If a copy of the MPL was not distributed with this

 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#ifndef mozilla_AccessibleCaretEventHub_h

#define mozilla_AccessibleCaretEventHub_h

#include "mozilla/EventForwards.h"

#include "mozilla/UniquePtr.h"

#include "mozilla/WeakPtr.h"

#include "nsCOMPtr.h"

#include "nsDocShell.h"

#include "nsIFrame.h"

#include "nsIReflowObserver.h"

#include "nsIScrollObserver.h"

#include "nsPoint.h"

#include "mozilla/RefPtr.h"

#include "nsWeakReference.h"

class nsIPresShell;

class nsITimer;

class nsIDocument;

namespace mozilla {

class AccessibleCaretManager;

class WidgetKeyboardEvent;

class WidgetMouseEvent;

class WidgetTouchEvent;

// -----------------------------------------------------------------------------

// Each PresShell holds a shared pointer to an AccessibleCaretEventHub; each

// AccessibleCaretEventHub holds a unique pointer to an AccessibleCaretManager.

// Thus, there's one AccessibleCaretManager per PresShell.

//

// AccessibleCaretEventHub implements a state pattern. It receives events from

// PresShell and callbacks by observers and listeners, and then relays them to

// the current concrete state which calls necessary event-handling methods in

// AccessibleCaretManager.

//

// We separate AccessibleCaretEventHub from AccessibleCaretManager to make the

// state transitions in AccessibleCaretEventHub testable. We put (nearly) all

// the operations involving PresShell, Selection, and AccessibleCaret

// manipulation in AccessibleCaretManager so that we can mock methods in

// AccessibleCaretManager in gtest. We test the correctness of the state

// transitions by giving events, callbacks, and the return values by mocked

// methods of AccessibleCaretEventHub. See TestAccessibleCaretEventHub.cpp.

//

// Besides dealing with real events, AccessibleCaretEventHub could also

// synthesize fake long-tap events and inject those events to itself on the

// platform lacks eMouseLongTap. Turn on this preference

// "layout.accessiblecaret.use_long_tap_injector" for the fake long-tap events.

//

// State transition diagram:

// https://hg.mozilla.org/mozilla-central/raw-file/default/layout/base/doc/AccessibleCaretEventHubStates.png

// Source code of the diagram:

// https://hg.mozilla.org/mozilla-central/file/default/layout/base/doc/AccessibleCaretEventHubStates.dot

//

// Please see the wiki page for more information.

// https://wiki.mozilla.org/AccessibleCaret

//

class AccessibleCaretEventHub

  : public nsIReflowObserver

  , public nsIScrollObserver

  , public nsSupportsWeakReference

{

public:

  explicit AccessibleCaretEventHub(nsIPresShell* aPresShell);

  void Init();

  void Terminate();

  MOZ_CAN_RUN_SCRIPT

  nsEventStatus HandleEvent(WidgetEvent* aEvent);

  // Call this function to notify the blur event happened.

  MOZ_CAN_RUN_SCRIPT

  void NotifyBlur(bool aIsLeavingDocument);

  NS_DECL_ISUPPORTS

  // nsIReflowObserver

  MOZ_CAN_RUN_SCRIPT_BOUNDARY

  NS_IMETHOD Reflow(DOMHighResTimeStamp start,

                    DOMHighResTimeStamp end) final;

  MOZ_CAN_RUN_SCRIPT_BOUNDARY

  NS_IMETHOD ReflowInterruptible(DOMHighResTimeStamp start,

                                 DOMHighResTimeStamp end) final;

  // Override nsIScrollObserver methods.

  MOZ_CAN_RUN_SCRIPT_BOUNDARY

  virtual void ScrollPositionChanged() override;

  MOZ_CAN_RUN_SCRIPT

  virtual void AsyncPanZoomStarted() override;

  MOZ_CAN_RUN_SCRIPT

  virtual void AsyncPanZoomStopped() override;

  // Base state

  class State;

  State* GetState() const;

  MOZ_CAN_RUN_SCRIPT

  void OnSelectionChange(nsIDocument* aDocument,

                         dom::Selection* aSelection,

                         int16_t aReason);

protected:

  virtual ~AccessibleCaretEventHub() = default;

#define MOZ_DECL_STATE_CLASS_GETTER(aClassName)                                \

  class aClassName;                                                            \

  static State* aClassName();

#define MOZ_IMPL_STATE_CLASS_GETTER(aClassName)                                \

  AccessibleCaretEventHub::State* AccessibleCaretEventHub::aClassName()        \

  {                                                                            \

    static class aClassName singleton;                                         \

    return &singleton;                                                         \

  }

  // Concrete state getters

  MOZ_DECL_STATE_CLASS_GETTER(NoActionState)

  MOZ_DECL_STATE_CLASS_GETTER(PressCaretState)

  MOZ_DECL_STATE_CLASS_GETTER(DragCaretState)

  MOZ_DECL_STATE_CLASS_GETTER(PressNoCaretState)

  MOZ_DECL_STATE_CLASS_GETTER(ScrollState)

  MOZ_DECL_STATE_CLASS_GETTER(LongTapState)

  void SetState(State* aState);

  MOZ_CAN_RUN_SCRIPT

  nsEventStatus HandleMouseEvent(WidgetMouseEvent* aEvent);

  MOZ_CAN_RUN_SCRIPT

  nsEventStatus HandleTouchEvent(WidgetTouchEvent* aEvent);

  MOZ_CAN_RUN_SCRIPT

  nsEventStatus HandleKeyboardEvent(WidgetKeyboardEvent* aEvent);

  virtual nsPoint GetTouchEventPosition(WidgetTouchEvent* aEvent,

                                        int32_t aIdentifier) const;

  virtual nsPoint GetMouseEventPosition(WidgetMouseEvent* aEvent) const;

  bool MoveDistanceIsLarge(const nsPoint& aPoint) const;

  void LaunchLongTapInjector();

  void CancelLongTapInjector();

  MOZ_CAN_RUN_SCRIPT_BOUNDARY

  static void FireLongTap(nsITimer* aTimer, void* aAccessibleCaretEventHub);

  void LaunchScrollEndInjector();

  void CancelScrollEndInjector();

  MOZ_CAN_RUN_SCRIPT_BOUNDARY

  static void FireScrollEnd(nsITimer* aTimer, void* aAccessibleCaretEventHub);

  // Member variables

  State* mState = NoActionState();

  // Will be set to nullptr in Terminate().

  nsIPresShell* MOZ_NON_OWNING_REF mPresShell = nullptr;

  UniquePtr<AccessibleCaretManager> mManager;

  WeakPtr<nsDocShell> mDocShell;

  // Use this timer for injecting a long tap event when APZ is disabled. If APZ

  // is enabled, it will send long tap event to us.

  nsCOMPtr<nsITimer> mLongTapInjectorTimer;

  // Last mouse button down event or touch start event point.

  nsPoint mPressPoint{ NS_UNCONSTRAINEDSIZE, NS_UNCONSTRAINEDSIZE };

  // For filter multitouch event

  int32_t mActiveTouchId = kInvalidTouchId;

  // Flag to indicate the class has been initialized.

  bool mInitialized = false;

  // Flag to avoid calling Reflow() callback recursively.

  bool mIsInReflowCallback = false;

  static const int32_t kMoveStartToleranceInPixel = 5;

  static const int32_t kInvalidTouchId = -1;

  static const int32_t kDefaultTouchId = 0; // For mouse event

};

// -----------------------------------------------------------------------------

// The base class for concrete states. A concrete state should inherit from this

// class, and override the methods to handle the events or callbacks. A concrete

// state is also responsible for transforming itself to the next concrete state.

//

class AccessibleCaretEventHub::State

{

public:

  virtual const char* Name() const { return ""; }

  virtual nsEventStatus OnPress(AccessibleCaretEventHub* aContext,

                                const nsPoint& aPoint, int32_t aTouchId,

                                EventClassID aEventClass)

  {

    return nsEventStatus_eIgnore;

  }

  virtual nsEventStatus OnMove(AccessibleCaretEventHub* aContext,

                               const nsPoint& aPoint)

  {

    return nsEventStatus_eIgnore;

  }

  virtual nsEventStatus OnRelease(AccessibleCaretEventHub* aContext)

  {

    return nsEventStatus_eIgnore;

  }

  virtual nsEventStatus OnLongTap(AccessibleCaretEventHub* aContext,

                                  const nsPoint& aPoint)

  {

    return nsEventStatus_eIgnore;

  }

  virtual void OnScrollStart(AccessibleCaretEventHub* aContext) {}

  virtual void OnScrollEnd(AccessibleCaretEventHub* aContext) {}

  virtual void OnScrollPositionChanged(AccessibleCaretEventHub* aContext) {}

  virtual void OnBlur(AccessibleCaretEventHub* aContext,

                      bool aIsLeavingDocument) {}

  virtual void OnSelectionChanged(AccessibleCaretEventHub* aContext,

                                  nsIDocument* aDoc, dom::Selection* aSel,

                                  int16_t aReason) {}

  virtual void OnReflow(AccessibleCaretEventHub* aContext) {}

  virtual void Enter(AccessibleCaretEventHub* aContext) {}

  virtual void Leave(AccessibleCaretEventHub* aContext) {}

  explicit State() = default;

  virtual ~State() = default;

  State(const State&) = delete;

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

};

} // namespace mozilla

#endif // mozilla_AccessibleCaretEventHub_h