/* -*- 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_ContentEventHandler_h_

#define mozilla_ContentEventHandler_h_

#include "mozilla/EventForwards.h"

#include "mozilla/dom/Selection.h"

#include "nsCOMPtr.h"

#include "nsIFrame.h"

#include "nsINode.h"

#include "nsISelectionController.h"

class nsPresContext;

class nsRange;

struct nsRect;

namespace mozilla {

enum LineBreakType

{

  LINE_BREAK_TYPE_NATIVE,

  LINE_BREAK_TYPE_XP

};

/*

 * Query Content Event Handler

 *   ContentEventHandler is a helper class for EventStateManager.

 *   The platforms request some content informations, e.g., the selected text,

 *   the offset of the selected text and the text for specified range.

 *   This class answers to NS_QUERY_* events from actual contents.

 */

class MOZ_STACK_CLASS ContentEventHandler

{

private:

  /**

   * RawRange is a helper class of ContentEventHandler class.  The caller is

   * responsible for making sure the start/end nodes are in document order.

   * This is enforced by assertions in DEBUG builds.

   */

  class MOZ_STACK_CLASS RawRange final

  {

  public:

    RawRange() {}

    void Clear()

    {

      mRoot = nullptr;

      mStart = RangeBoundary();

      mEnd = RangeBoundary();

    }

    bool IsPositioned() const

    {

      return mStart.IsSet() && mEnd.IsSet();

    }

    bool Collapsed() const

    {

      return mStart == mEnd && IsPositioned();

    }

    nsINode* GetStartContainer() const { return mStart.Container(); }

    nsINode* GetEndContainer() const { return mEnd.Container(); }

    uint32_t StartOffset() const { return mStart.Offset(); }

    uint32_t EndOffset() const { return mEnd.Offset(); }

    nsIContent* StartRef() const { return mStart.Ref(); }

    nsIContent* EndRef() const { return mEnd.Ref(); }

    const RangeBoundary& Start() const { return mStart; }

    const RangeBoundary& End() const { return mEnd; }

    // XXX: Make these use RangeBoundaries...

    nsresult CollapseTo(const RawRangeBoundary& aBoundary)

    {

      return SetStartAndEnd(aBoundary, aBoundary);

    }

    nsresult SetStart(const RawRangeBoundary& aStart);

    nsresult SetEnd(const RawRangeBoundary& aEnd);

    // NOTE: These helpers can hide performance problems, as they perform a

    // search to find aStartOffset in aStartContainer.

    nsresult SetStart(nsINode* aStartContainer, uint32_t aStartOffset) {

      return SetStart(RawRangeBoundary(aStartContainer, aStartOffset));

    }

    nsresult SetEnd(nsINode* aEndContainer, uint32_t aEndOffset) {

      return SetEnd(RawRangeBoundary(aEndContainer, aEndOffset));

    }

    nsresult SetEndAfter(nsINode* aEndContainer);

    void SetStartAndEnd(const nsRange* aRange);

    nsresult SetStartAndEnd(const RawRangeBoundary& aStart,

                            const RawRangeBoundary& aEnd);

    nsresult SelectNodeContents(nsINode* aNodeToSelectContents);

  private:

    nsINode* IsValidBoundary(nsINode* aNode) const;

    inline void AssertStartIsBeforeOrEqualToEnd();

    nsCOMPtr<nsINode> mRoot;

    RangeBoundary mStart;

    RangeBoundary mEnd;

  };

public:

  typedef dom::Selection Selection;

  explicit ContentEventHandler(nsPresContext* aPresContext);

  // Handle aEvent in the current process.

  nsresult HandleQueryContentEvent(WidgetQueryContentEvent* aEvent);

  // eQuerySelectedText event handler

  nsresult OnQuerySelectedText(WidgetQueryContentEvent* aEvent);

  // eQueryTextContent event handler

  nsresult OnQueryTextContent(WidgetQueryContentEvent* aEvent);

  // eQueryCaretRect event handler

  nsresult OnQueryCaretRect(WidgetQueryContentEvent* aEvent);

  // eQueryTextRect event handler

  nsresult OnQueryTextRect(WidgetQueryContentEvent* aEvent);

  // eQueryTextRectArray event handler

  nsresult OnQueryTextRectArray(WidgetQueryContentEvent* aEvent);

  // eQueryEditorRect event handler

  nsresult OnQueryEditorRect(WidgetQueryContentEvent* aEvent);

  // eQueryContentState event handler

  nsresult OnQueryContentState(WidgetQueryContentEvent* aEvent);

  // eQuerySelectionAsTransferable event handler

  nsresult OnQuerySelectionAsTransferable(WidgetQueryContentEvent* aEvent);

  // eQueryCharacterAtPoint event handler

  nsresult OnQueryCharacterAtPoint(WidgetQueryContentEvent* aEvent);

  // eQueryDOMWidgetHittest event handler

  nsresult OnQueryDOMWidgetHittest(WidgetQueryContentEvent* aEvent);

  // NS_SELECTION_* event

  nsresult OnSelectionEvent(WidgetSelectionEvent* aEvent);

protected:

  nsCOMPtr<nsIDocument> mDocument;

  // mSelection is typically normal selection but if OnQuerySelectedText()

  // is called, i.e., handling eQuerySelectedText, it's the specified selection

  // by WidgetQueryContentEvent::mInput::mSelectionType.

  RefPtr<Selection> mSelection;

  // mFirstSelectedRawRange is initialized from the first range of mSelection,

  // if it exists.  Otherwise, it is reset by Clear().

  RawRange mFirstSelectedRawRange;

  nsCOMPtr<nsIContent> mRootContent;

  nsresult Init(WidgetQueryContentEvent* aEvent);

  nsresult Init(WidgetSelectionEvent* aEvent);

  nsresult InitBasic();

  nsresult InitCommon(SelectionType aSelectionType = SelectionType::eNormal);

  /**

   * InitRootContent() computes the root content of current focused editor.

   *

   * @param aNormalSelection    This must be a Selection instance whose type is

   *                            SelectionType::eNormal.

   */

  nsresult InitRootContent(Selection* aNormalSelection);

public:

  // FlatText means the text that is generated from DOM tree. The BR elements

  // are replaced to native linefeeds. Other elements are ignored.

  // NodePosition stores a pair of node and offset in the node.

  // When mNode is an element and mOffset is 0, the start position means after

  // the open tag of mNode.

  // This is useful to receive one or more sets of them instead of nsRange.

  // This type is intended to be used for short-lived operations, and is thus

  // marked MOZ_STACK_CLASS.

  struct MOZ_STACK_CLASS NodePosition : public RangeBoundary

  {

    // Only when mNode is an element node and mOffset is 0, mAfterOpenTag is

    // referred.

    bool mAfterOpenTag = true;

    NodePosition()

      : RangeBoundary()

    {

    }

    NodePosition(nsINode* aContainer, int32_t aOffset)

      : RangeBoundary(aContainer, aOffset)

    {

    }

    NodePosition(nsINode* aContainer, nsIContent* aRef)

      : RangeBoundary(aContainer, aRef)

    {

    }

    explicit NodePosition(const nsIFrame::ContentOffsets& aContentOffsets)

      : RangeBoundary(aContentOffsets.content, aContentOffsets.offset)

    {

    }

  public:

    bool operator==(const NodePosition& aOther) const

    {

      return RangeBoundary::operator==(aOther) &&

        mAfterOpenTag == aOther.mAfterOpenTag;

    }

    bool IsBeforeOpenTag() const

    {

      return IsSet() &&

        Container()->IsElement() &&

        !Ref() &&

        !mAfterOpenTag;

    }

    bool IsImmediatelyAfterOpenTag() const

    {

      return IsSet() &&

        Container()->IsElement() &&

        !Ref() &&

        mAfterOpenTag;

    }

  };

  // NodePositionBefore isn't good name if Container() isn't an element node nor

  // Offset() is not 0, though, when Container() is an element node and mOffset

  // is 0, this is treated as before the open tag of Container().

  struct NodePositionBefore final : public NodePosition

  {

    NodePositionBefore(nsINode* aContainer, int32_t aOffset)

      : NodePosition(aContainer, aOffset)

    {

      mAfterOpenTag = false;

    }

    NodePositionBefore(nsINode* aContainer, nsIContent* aRef)

      : NodePosition(aContainer, aRef)

    {

      mAfterOpenTag = false;

    }

  };

  // Get the flatten text length in the range.

  // @param aStartPosition      Start node and offset in the node of the range.

  // @param aEndPosition        End node and offset in the node of the range.

  // @param aRootContent        The root content of the editor or document.

  //                            aRootContent won't cause any text including

  //                            line breaks.

  // @param aLength             The result of the flatten text length of the

  //                            range.

  // @param aLineBreakType      Whether this computes flatten text length with

  //                            native line breakers on the platform or

  //                            with XP line breaker (\n).

  // @param aIsRemovingNode     Should be true only when this is called from

  //                            nsIMutationObserver::ContentRemoved().

  //                            When this is true, aStartPosition.mNode should

  //                            be the root node of removing nodes and mOffset

  //                            should be 0 and aEndPosition.mNode should be

  //                            same as aStartPosition.mNode and mOffset should

  //                            be number of the children of mNode.

  static nsresult GetFlatTextLengthInRange(const NodePosition& aStartPosition,

                                           const NodePosition& aEndPosition,

                                           nsIContent* aRootContent,

                                           uint32_t* aLength,

                                           LineBreakType aLineBreakType,

                                           bool aIsRemovingNode = false);

  // Computes the native text length between aStartOffset and aEndOffset of

  // aContent.  aContent must be a text node.

  static uint32_t GetNativeTextLength(nsIContent* aContent,

                                      uint32_t aStartOffset,

                                      uint32_t aEndOffset);

  // Get the native text length of aContent.  aContent must be a text node.

  static uint32_t GetNativeTextLength(nsIContent* aContent,

                                      uint32_t aMaxLength = UINT32_MAX);

  // Get the native text length which is inserted before aContent.

  // aContent should be an element.

  static uint32_t GetNativeTextLengthBefore(nsIContent* aContent,

                                            nsINode* aRootNode);

protected:

  // Get the text length of aContent.  aContent must be a text node.

  static uint32_t GetTextLength(nsIContent* aContent,

                                LineBreakType aLineBreakType,

                                uint32_t aMaxLength = UINT32_MAX);

  // Get the text length of a given range of a content node in

  // the given line break type.

  static uint32_t GetTextLengthInRange(nsIContent* aContent,

                                       uint32_t aXPStartOffset,

                                       uint32_t aXPEndOffset,

                                       LineBreakType aLineBreakType);

  // Get the contents in aContent (meaning all children of aContent) as plain

  // text.  E.g., specifying mRootContent gets whole text in it.

  // Note that the result is not same as .textContent.  The result is

  // optimized for native IMEs.  For example, <br> element and some block

  // elements causes "\n" (or "\r\n"), see also ShouldBreakLineBefore().

  nsresult GenerateFlatTextContent(nsIContent* aContent,

                                   nsString& aString,

                                   LineBreakType aLineBreakType);

  // Get the contents of aRange as plain text.

  nsresult GenerateFlatTextContent(const RawRange& aRawRange,

                                   nsString& aString,

                                   LineBreakType aLineBreakType);

  // Get offset of start of aRange.  Note that the result includes the length

  // of line breaker caused by the start of aContent because aRange never

  // includes the line breaker caused by its start node.

  nsresult GetStartOffset(const RawRange& aRawRange,

                          uint32_t* aOffset,

                          LineBreakType aLineBreakType);

  // Check if we should insert a line break before aContent.

  // This should return false only when aContent is an html element which

  // is typically used in a paragraph like <em>.

  static bool ShouldBreakLineBefore(nsIContent* aContent,

                                    nsINode* aRootNode);

  // Get the line breaker length.

  static inline uint32_t GetBRLength(LineBreakType aLineBreakType);

  static LineBreakType GetLineBreakType(WidgetQueryContentEvent* aEvent);

  static LineBreakType GetLineBreakType(WidgetSelectionEvent* aEvent);

  static LineBreakType GetLineBreakType(bool aUseNativeLineBreak);

  // Returns focused content (including its descendant documents).

  nsIContent* GetFocusedContent();

  // Returns true if the content is a plugin host.

  bool IsPlugin(nsIContent* aContent);

  // QueryContentRect() sets the rect of aContent's frame(s) to aEvent.

  nsresult QueryContentRect(nsIContent* aContent,

                            WidgetQueryContentEvent* aEvent);

  // Initialize aRawRange from the offset of FlatText and the text length.

  // If aExpandToClusterBoundaries is true, the start offset and the end one are

  // expanded to nearest cluster boundaries.

  nsresult SetRawRangeFromFlatTextOffset(RawRange* aRawRange,

                                         uint32_t aOffset,

                                         uint32_t aLength,

                                         LineBreakType aLineBreakType,

                                         bool aExpandToClusterBoundaries,

                                         uint32_t* aNewOffset = nullptr,

                                         nsIContent** aLastTextNode = nullptr);

  // If the aCollapsedRawRange isn't in text node but next to a text node,

  // this method modifies it in the text node.  Otherwise, not modified.

  nsresult AdjustCollapsedRangeMaybeIntoTextNode(RawRange& aCollapsedRawRange);

  // Convert the frame relative offset to be relative to the root frame of the

  // root presContext (but still measured in appUnits of aFrame's presContext).

  nsresult ConvertToRootRelativeOffset(nsIFrame* aFrame,

                                       nsRect& aRect);

  // Expand aXPOffset to the nearest offset in cluster boundary. aForward is

  // true, it is expanded to forward.

  nsresult ExpandToClusterBoundary(nsIContent* aContent, bool aForward,

                                   uint32_t* aXPOffset);

  typedef nsTArray<mozilla::FontRange> FontRangeArray;

  static void AppendFontRanges(FontRangeArray& aFontRanges,

                               nsIContent* aContent,

                               uint32_t aBaseOffset,

                               uint32_t aXPStartOffset,

                               uint32_t aXPEndOffset,

                               LineBreakType aLineBreakType);

  nsresult GenerateFlatFontRanges(const RawRange& aRawRange,

                                  FontRangeArray& aFontRanges,

                                  uint32_t& aLength,

                                  LineBreakType aLineBreakType);

  nsresult QueryTextRectByRange(const RawRange& aRawRange,

                                LayoutDeviceIntRect& aRect,

                                WritingMode& aWritingMode);

  struct MOZ_STACK_CLASS FrameAndNodeOffset final

  {

    // mFrame is safe since this can live in only stack class and

    // ContentEventHandler doesn't modify layout after

    // ContentEventHandler::Init() flushes pending layout.  In other words,

    // this struct shouldn't be used before calling

    // ContentEventHandler::Init().

    nsIFrame* mFrame;

    // offset in the node of mFrame

    int32_t mOffsetInNode;

    FrameAndNodeOffset()

      : mFrame(nullptr)

      , mOffsetInNode(-1)

    {

    }

    FrameAndNodeOffset(nsIFrame* aFrame, int32_t aStartOffsetInNode)

      : mFrame(aFrame)

      , mOffsetInNode(aStartOffsetInNode)

    {

    }

    nsIFrame* operator->() { return mFrame; }

    const nsIFrame* operator->() const { return mFrame; }

    operator nsIFrame*() { return mFrame; }

    operator const nsIFrame*() const { return mFrame; }

    bool IsValid() const { return mFrame && mOffsetInNode >= 0; }

  };

  // Get first frame after the start of the given range for computing text rect.

  // This returns invalid FrameAndNodeOffset if there is no content which

  // should affect to computing text rect in the range.  mOffsetInNode is start

  // offset in the frame.

  FrameAndNodeOffset GetFirstFrameInRangeForTextRect(const RawRange& aRawRange);

  // Get last frame before the end of the given range for computing text rect.

  // This returns invalid FrameAndNodeOffset if there is no content which

  // should affect to computing text rect in the range.  mOffsetInNode is end

  // offset in the frame.

  FrameAndNodeOffset GetLastFrameInRangeForTextRect(const RawRange& aRawRange);

  struct MOZ_STACK_CLASS FrameRelativeRect final

  {

    // mRect is relative to the mBaseFrame's position.

    nsRect mRect;

    nsIFrame* mBaseFrame;

    FrameRelativeRect()

      : mBaseFrame(nullptr)

    {

    }

    explicit FrameRelativeRect(nsIFrame* aBaseFrame)

      : mBaseFrame(aBaseFrame)

    {

    }

    FrameRelativeRect(const nsRect& aRect, nsIFrame* aBaseFrame)

      : mRect(aRect)

      , mBaseFrame(aBaseFrame)

    {

    }

    bool IsValid() const { return mBaseFrame != nullptr; }

    // Returns an nsRect relative to aBaseFrame instead of mBaseFrame.

    nsRect RectRelativeTo(nsIFrame* aBaseFrame) const;

  };

  // Returns a rect for line breaker before the node of aFrame (If aFrame is

  // a <br> frame or a block level frame, it causes a line break at its

  // element's open tag, see also ShouldBreakLineBefore()).  Note that this

  // doesn't check if aFrame should cause line break in non-debug build.

  FrameRelativeRect GetLineBreakerRectBefore(nsIFrame* aFrame);

  // Returns a line breaker rect after aTextContent as there is a line breaker

  // immediately after aTextContent.  This is useful when following block

  // element causes a line break before it and it needs to compute the line

  // breaker's rect.  For example, if there is |<p>abc</p><p>def</p>|, the

  // rect of 2nd <p>'s line breaker should be at right of "c" in the first

  // <p>, not the start of 2nd <p>.  The result is relative to the last text

  // frame which represents the last character of aTextContent.

  FrameRelativeRect GuessLineBreakerRectAfter(nsIContent* aTextContent);

  // Returns a guessed first rect.  I.e., it may be different from actual

  // caret when selection is collapsed at start of aFrame.  For example, this

  // guess the caret rect only with the content box of aFrame and its font

  // height like:

  // +-aFrame----------------- (border box)

  // |

  // |  +--------------------- (content box)

  // |  | I

  //      ^ guessed caret rect

  // However, actual caret is computed with more information like line-height,

  // child frames of aFrame etc.  But this does not emulate actual caret

  // behavior exactly for simpler and faster code because it's difficult and

  // we're not sure it's worthwhile to do it with complicated implementation.

  FrameRelativeRect GuessFirstCaretRectIn(nsIFrame* aFrame);

  // Make aRect non-empty.  If width and/or height is 0, these methods set them

  // to 1.  Note that it doesn't set nsRect's width nor height to one device

  // pixel because using nsRect::ToOutsidePixels() makes actual width or height

  // to 2 pixels because x and y may not be aligned to device pixels.

  void EnsureNonEmptyRect(nsRect& aRect) const;

  void EnsureNonEmptyRect(LayoutDeviceIntRect& aRect) const;

};

} // namespace mozilla

#endif // mozilla_ContentEventHandler_h_