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

#include "APZUtils.h"
#include "DragTracker.h"
#include "InputData.h"
#include "mozilla/EventForwards.h"
#include "mozilla/RefPtr.h"
#include "mozilla/UniquePtr.h"
#include "nsTArray.h"
#include "TouchCounter.h"

namespace mozilla {

class InputData;
class MultiTouchInput;
class ScrollWheelInput;

namespace layers {

class AsyncPanZoomController;
class CancelableBlockState;
class TouchBlockState;
class WheelBlockState;
class DragBlockState;
class PanGestureBlockState;
class AsyncDragMetrics;
class QueuedInput;

/**
 * This class stores incoming input events, associated with "input blocks", until
 * they are ready for handling.
 */
class InputQueue {
  NS_INLINE_DECL_THREADSAFE_REFCOUNTING(InputQueue)

public:
  InputQueue();

  /**
   * Notifies the InputQueue of a new incoming input event. The APZC that the
   * input event was targeted to should be provided in the |aTarget| parameter.
   * See the documentation on APZCTreeManager::ReceiveInputEvent for info on
   * return values from this function, including |aOutInputBlockId|.
   */
  nsEventStatus ReceiveInputEvent(const RefPtr<AsyncPanZoomController>& aTarget,
                                  bool aTargetConfirmed,
                                  const InputData& aEvent,
                                  uint64_t* aOutInputBlockId);
  /**
   * This function should be invoked to notify the InputQueue when web content
   * decides whether or not it wants to cancel a block of events. The block
   * id to which this applies should be provided in |aInputBlockId|.
   */
  void ContentReceivedInputBlock(uint64_t aInputBlockId, bool aPreventDefault);
  /**
   * This function should be invoked to notify the InputQueue once the target
   * APZC to handle an input block has been confirmed. In practice this should
   * generally be decidable upon receipt of the input event, but in some cases
   * we may need to query the layout engine to know for sure. The input block
   * this applies to should be specified via the |aInputBlockId| parameter.
   */
  void SetConfirmedTargetApzc(uint64_t aInputBlockId, const RefPtr<AsyncPanZoomController>& aTargetApzc);
  /**
   * This function is invoked to confirm that the drag block should be handled
   * by the APZ.
   */
  void ConfirmDragBlock(uint64_t aInputBlockId,
                        const RefPtr<AsyncPanZoomController>& aTargetApzc,
                        const AsyncDragMetrics& aDragMetrics);
  /**
   * This function should be invoked to notify the InputQueue of the touch-
   * action properties for the different touch points in an input block. The
   * input block this applies to should be specified by the |aInputBlockId|
   * parameter. If touch-action is not enabled on the platform, this function
   * does nothing and need not be called.
   */
  void SetAllowedTouchBehavior(uint64_t aInputBlockId, const nsTArray<TouchBehaviorFlags>& aBehaviors);
  /**
   * Adds a new touch block at the end of the input queue that has the same
   * allowed touch behaviour flags as the the touch block currently being
   * processed. This should only be called when processing of a touch block
   * triggers the creation of a new touch block. Returns the input block id
   * of the the newly-created block.
   */
  uint64_t InjectNewTouchBlock(AsyncPanZoomController* aTarget);
  /**
   * Returns the pending input block at the head of the queue, if there is one.
   * This may return null if there all input events have been processed.
   */
  CancelableBlockState* GetCurrentBlock() const;
  /*
   * Returns the current pending input block as a specific kind of block. If
   * GetCurrentBlock() returns null, these functions additionally check the
   * mActiveXXXBlock field of the corresponding input type to see if there is
   * a depleted but still active input block, and returns that if found. These
   * functions may return null if no block is found.
   */
  TouchBlockState* GetCurrentTouchBlock() const;
  WheelBlockState* GetCurrentWheelBlock() const;
  DragBlockState* GetCurrentDragBlock() const;
  PanGestureBlockState* GetCurrentPanGestureBlock() const;
  /**
   * Returns true iff the pending block at the head of the queue is a touch
   * block and is ready for handling.
   */
  bool HasReadyTouchBlock() const;
  /**
   * If there is an active wheel transaction, returns the WheelBlockState
   * representing the transaction. Otherwise, returns null. "Active" in this
   * function name is the same kind of "active" as in mActiveWheelBlock - that
   * is, new incoming wheel events will go into the "active" block.
   */
  WheelBlockState* GetActiveWheelTransaction() const;
  /**
   * Remove all input blocks from the input queue.
   */
  void Clear();
  /**
   * Whether the current pending block allows scroll handoff.
   */
  bool AllowScrollHandoff() const;
  /**
   * If there is currently a drag in progress, return whether or not it was
   * targeted at a scrollbar. If the drag was newly-created and doesn't know,
   * use the provided |aOnScrollbar| to populate that information.
   */
  bool IsDragOnScrollbar(bool aOnScrollbar);

private:
  ~InputQueue();

  TouchBlockState* StartNewTouchBlock(const RefPtr<AsyncPanZoomController>& aTarget,
                                      bool aTargetConfirmed,
                                      bool aCopyPropertiesFromCurrent);

  /**
   * If animations are present for the current pending input block, cancel
   * them as soon as possible.
   */
  void CancelAnimationsForNewBlock(CancelableBlockState* aBlock);

  /**
   * If we need to wait for a content response, schedule that now.
   */
  void MaybeRequestContentResponse(const RefPtr<AsyncPanZoomController>& aTarget,
                                   CancelableBlockState* aBlock);

  nsEventStatus ReceiveTouchInput(const RefPtr<AsyncPanZoomController>& aTarget,
                                  bool aTargetConfirmed,
                                  const MultiTouchInput& aEvent,
                                  uint64_t* aOutInputBlockId);
  nsEventStatus ReceiveMouseInput(const RefPtr<AsyncPanZoomController>& aTarget,
                                  bool aTargetConfirmed,
                                  const MouseInput& aEvent,
                                  uint64_t* aOutInputBlockId);
  nsEventStatus ReceiveScrollWheelInput(const RefPtr<AsyncPanZoomController>& aTarget,
                                        bool aTargetConfirmed,
                                        const ScrollWheelInput& aEvent,
                                        uint64_t* aOutInputBlockId);
  nsEventStatus ReceivePanGestureInput(const RefPtr<AsyncPanZoomController>& aTarget,
                                        bool aTargetConfirmed,
                                        const PanGestureInput& aEvent,
                                        uint64_t* aOutInputBlockId);

  /**
   * Helper function that searches mQueuedInputs for the first block matching
   * the given id, and returns it. If |aOutFirstInput| is non-null, it is
   * populated with a pointer to the first input in mQueuedInputs that
   * corresponds to the block, or null if no such input was found. Note that
   * even if there are no inputs in mQueuedInputs, this function can return
   * non-null if the block id provided matches one of the depleted-but-still-
   * active blocks (mActiveTouchBlock, mActiveWheelBlock, etc.).
   */
  CancelableBlockState* FindBlockForId(uint64_t aInputBlockId,
                                       InputData** aOutFirstInput);
  void ScheduleMainThreadTimeout(const RefPtr<AsyncPanZoomController>& aTarget,
                                 CancelableBlockState* aBlock);
  void MainThreadTimeout(uint64_t aInputBlockId);
  void ProcessQueue();
  bool CanDiscardBlock(CancelableBlockState* aBlock);
  void UpdateActiveApzc(const RefPtr<AsyncPanZoomController>& aNewActive);

private:
  // The queue of input events that have not yet been fully processed.
  // This member must only be accessed on the controller/UI thread.
  nsTArray<UniquePtr<QueuedInput>> mQueuedInputs;

  // These are the most recently created blocks of each input type. They are
  // "active" in the sense that new inputs of that type are associated with
  // them. Note that these pointers may be null if no inputs of the type have
  // arrived, or if the inputs for the type formed a complete block that was
  // then discarded.
  RefPtr<TouchBlockState> mActiveTouchBlock;
  RefPtr<WheelBlockState> mActiveWheelBlock;
  RefPtr<DragBlockState> mActiveDragBlock;
  RefPtr<PanGestureBlockState> mActivePanGestureBlock;

  // The APZC to which the last event was delivered
  RefPtr<AsyncPanZoomController> mLastActiveApzc;

  // Track touches so we know when to clear mLastActiveApzc
  TouchCounter mTouchCounter;

  // Track mouse inputs so we know if we're in a drag or not
  DragTracker mDragTracker;
};

} // namespace layers
} // namespace mozilla

#endif // mozilla_layers_InputQueue_h
