/* -*- Mode: C++; tab-width: 4; 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_a11y_SelectionManager_h__
#define mozilla_a11y_SelectionManager_h__

#include "nsISelectionController.h"
#include "nsISelectionListener.h"
#include "mozilla/WeakPtr.h"

namespace mozilla {

class PresShell;

namespace dom {
class AbstractRange;
class Element;
class Selection;
}  // namespace dom

namespace a11y {

class AccEvent;
class HyperTextAccessible;

/**
 * This special accessibility class is for the caret and selection management.
 * There is only 1 visible caret per top level window. However, there may be
 * several visible selections.
 *
 * The important selections are the one owned by each document, and the one in
 * the currently focused control.
 *
 * On Windows this class is used to move an invisible system caret that
 * shadows the Mozilla caret. Windows will also automatically map this to
 * the MSAA caret accessible object (via OBJID_CARET) (as opposed to the root
 * accessible tree for a window which is retrieved with OBJID_CLIENT).
 *
 * For ATK and IAccessible2, this class is used to fire caret move and
 * selection change events.
 */

struct SelData;

class SelectionManager : public nsISelectionListener {
 public:
  // nsISupports
  // implemented by derived nsAccessibilityService

  // nsISelectionListener
  NS_DECL_NSISELECTIONLISTENER

  // SelectionManager
  void Shutdown() { ClearControlSelectionListener(); }

  /**
   * Listen to selection events on the focused control.
   *
   * Note: only one control's selection events are listened to at a time. This
   * will remove the previous control's selection listener.
   */
  void SetControlSelectionListener(dom::Element* aFocusedElm);

  /**
   * Stop listening to selection events on the control.
   */
  void ClearControlSelectionListener();

  /**
   * Listen to selection events on the document.
   */
  void AddDocSelectionListener(PresShell* aPresShell);

  /**
   * Stop listening to selection events for a given document
   */
  void RemoveDocSelectionListener(PresShell* aPresShell);

  /**
   * Process delayed event, results in caret move and text selection change
   * events.
   */
  void ProcessTextSelChangeEvent(AccEvent* aEvent);

  /**
   * Gets the current caret offset/hypertext accessible pair. If there is no
   * current pair, then returns -1 for the offset and a nullptr for the
   * accessible.
   */
  inline HyperTextAccessible* AccessibleWithCaret(int32_t* aCaret) {
    if (aCaret) *aCaret = mCaretOffset;

    return mAccWithCaret;
  }

  /**
   * Update caret offset when it doesn't go through a caret move event.
   */
  inline void UpdateCaretOffset(HyperTextAccessible* aItem, int32_t aOffset) {
    mAccWithCaret = aItem;
    mCaretOffset = aOffset;
  }

  inline void ResetCaretOffset() {
    mCaretOffset = -1;
    mAccWithCaret = nullptr;
  }

  /**
   * Called by DOM when a selection range is added/removed.
   * We need this because nsISelectionListener isn't sufficient for spelling
   * errors, etc., since it only tells us that there was a change, not which
   * range changed. We don't want to unnecessarily push a cache update for all
   * Accessibles in the entire selection.
   * Returns false if these notifications aren't required for this selection
   * type at this time.
   */
  static bool SelectionRangeChanged(SelectionType aType,
                                    const dom::AbstractRange& aRange);

  ~SelectionManager();

 protected:
  SelectionManager();

  /**
   * Process DOM selection change. Fire selection and caret move events.
   */
  void ProcessSelectionChanged(SelData* aSelData);

 private:
  // Currently focused control.
  int32_t mCaretOffset;
  HyperTextAccessible* mAccWithCaret;
  WeakPtr<dom::Selection> mCurrCtrlNormalSel;
};

}  // namespace a11y
}  // namespace mozilla

#endif