/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=2 sw=2 et tw=78: */
/* ***** BEGIN LICENSE BLOCK *****
 * Version: MPL 1.1/GPL 2.0/LGPL 2.1
 *
 * The contents of this file are subject to the Mozilla Public License Version
 * 1.1 (the "License"); you may not use this file except in compliance with
 * the License. You may obtain a copy of the License at
 * http://www.mozilla.org/MPL/
 *
 * Software distributed under the License is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 * for the specific language governing rights and limitations under the
 * License.
 *
 * The Original Code is mozilla.org code.
 *
 * The Initial Developer of the Original Code is
 * Netscape Communications Corporation.
 * Portions created by the Initial Developer are Copyright (C) 1998
 * the Initial Developer. All Rights Reserved.
 *
 * Contributor(s):
 *   Pierre Phaneuf <pp@ludusdesign.com>
 *   Mats Palmgren <matspal@gmail.com>
 *
 * Alternatively, the contents of this file may be used under the terms of
 * either of the GNU General Public License Version 2 or later (the "GPL"),
 * or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
 * in which case the provisions of the GPL or the LGPL are applicable instead
 * of those above. If you wish to allow use of your version of this file only
 * under the terms of either the GPL or the LGPL, and not to allow others to
 * use your version of this file under the terms of the MPL, indicate your
 * decision by deleting the provisions above and replace them with the notice
 * and other provisions required by the GPL or the LGPL. If you do not delete
 * the provisions above, a recipient may use your version of this file under
 * the terms of any one of the MPL, the GPL or the LGPL.
 *
 * ***** END LICENSE BLOCK ***** */

/* the caret is the text cursor used, e.g., when editing */

#include "nsCOMPtr.h"

#include "nsITimer.h"

#include "nsIComponentManager.h"
#include "nsIServiceManager.h"
#include "nsFrameSelection.h"
#include "nsIFrame.h"
#include "nsIScrollableFrame.h"
#include "nsIDOMNode.h"
#include "nsIDOMRange.h"
#include "nsISelection.h"
#include "nsISelectionPrivate.h"
#include "nsIDOMCharacterData.h"
#include "nsIContent.h"
#include "nsIPresShell.h"
#include "nsRenderingContext.h"
#include "nsPresContext.h"
#include "nsBlockFrame.h"
#include "nsISelectionController.h"
#include "nsDisplayList.h"
#include "nsCaret.h"
#include "nsTextFrame.h"
#include "nsXULPopupManager.h"
#include "nsMenuPopupFrame.h"
#include "nsTextFragment.h"
#include "nsThemeConstants.h"
#include "mozilla/Preferences.h"
#include "mozilla/LookAndFeel.h"

// The bidi indicator hangs off the caret to one side, to show which
// direction the typing is in. It needs to be at least 2x2 to avoid looking like 
// an insignificant dot
static const PRInt32 kMinBidiIndicatorPixels = 2;

#ifdef IBMBIDI
#include "nsIBidiKeyboard.h"
#include "nsContentUtils.h"
#endif //IBMBIDI

using namespace mozilla;

/**
 * Find the first frame in an in-order traversal of the frame subtree rooted
 * at aFrame which is either a text frame logically at the end of a line,
 * or which is aStopAtFrame. Return null if no such frame is found. We don't
 * descend into the children of non-eLineParticipant frames.
 */
static nsIFrame*
CheckForTrailingTextFrameRecursive(nsIFrame* aFrame, nsIFrame* aStopAtFrame)
{
  if (aFrame == aStopAtFrame ||
      ((aFrame->GetType() == nsGkAtoms::textFrame &&
       (static_cast<nsTextFrame*>(aFrame))->IsAtEndOfLine())))
    return aFrame;
  if (!aFrame->IsFrameOfType(nsIFrame::eLineParticipant))
    return nsnull;

  for (nsIFrame* f = aFrame->GetFirstPrincipalChild(); f; f = f->GetNextSibling())
  {
    nsIFrame* r = CheckForTrailingTextFrameRecursive(f, aStopAtFrame);
    if (r)
      return r;
  }
  return nsnull;
}

static nsLineBox*
FindContainingLine(nsIFrame* aFrame)
{
  while (aFrame && aFrame->IsFrameOfType(nsIFrame::eLineParticipant))
  {
    nsIFrame* parent = aFrame->GetParent();
    nsBlockFrame* blockParent = nsLayoutUtils::GetAsBlock(parent);
    if (blockParent)
    {
      PRBool isValid;
      nsBlockInFlowLineIterator iter(blockParent, aFrame, &isValid);
      return isValid ? iter.GetLine().get() : nsnull;
    }
    aFrame = parent;
  }
  return nsnull;
}

static void
AdjustCaretFrameForLineEnd(nsIFrame** aFrame, PRInt32* aOffset)
{
  nsLineBox* line = FindContainingLine(*aFrame);
  if (!line)
    return;
  PRInt32 count = line->GetChildCount();
  for (nsIFrame* f = line->mFirstChild; count > 0; --count, f = f->GetNextSibling())
  {
    nsIFrame* r = CheckForTrailingTextFrameRecursive(f, *aFrame);
    if (r == *aFrame)
      return;
    if (r)
    {
      *aFrame = r;
      NS_ASSERTION(r->GetType() == nsGkAtoms::textFrame, "Expected text frame");
      *aOffset = (static_cast<nsTextFrame*>(r))->GetContentEnd();
      return;
    }
  }
}

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

nsCaret::nsCaret()
: mPresShell(nsnull)
, mBlinkRate(500)
, mVisible(PR_FALSE)
, mDrawn(PR_FALSE)
, mPendingDraw(PR_FALSE)
, mReadOnly(PR_FALSE)
, mShowDuringSelection(PR_FALSE)
, mIgnoreUserModify(PR_TRUE)
#ifdef IBMBIDI
, mKeyboardRTL(PR_FALSE)
, mLastBidiLevel(0)
#endif
, mLastContentOffset(0)
, mLastHint(nsFrameSelection::HINTLEFT)
{
}

//-----------------------------------------------------------------------------
nsCaret::~nsCaret()
{
  KillTimer();
}

//-----------------------------------------------------------------------------
nsresult nsCaret::Init(nsIPresShell *inPresShell)
{
  NS_ENSURE_ARG(inPresShell);

  mPresShell = do_GetWeakReference(inPresShell);    // the presshell owns us, so no addref
  NS_ASSERTION(mPresShell, "Hey, pres shell should support weak refs");

  // XXX we should just do this LookAndFeel consultation every time
  // we need these values.
  mCaretWidthCSSPx = LookAndFeel::GetInt(LookAndFeel::eIntID_CaretWidth, 1);
  mCaretAspectRatio =
    LookAndFeel::GetFloat(LookAndFeel::eFloatID_CaretAspectRatio, 0.0f);

  mBlinkRate = static_cast<PRUint32>(
    LookAndFeel::GetInt(LookAndFeel::eIntID_CaretBlinkTime, mBlinkRate));
  mShowDuringSelection =
    LookAndFeel::GetInt(LookAndFeel::eIntID_ShowCaretDuringSelection,
                        mShowDuringSelection ? 1 : 0) != 0;

  // get the selection from the pres shell, and set ourselves up as a selection
  // listener

  nsCOMPtr<nsISelectionController> selCon = do_QueryReferent(mPresShell);
  if (!selCon)
    return NS_ERROR_FAILURE;

  nsCOMPtr<nsISelection> domSelection;
  nsresult rv = selCon->GetSelection(nsISelectionController::SELECTION_NORMAL,
                                     getter_AddRefs(domSelection));
  if (NS_FAILED(rv))
    return rv;
  if (!domSelection)
    return NS_ERROR_FAILURE;

  nsCOMPtr<nsISelectionPrivate> privateSelection = do_QueryInterface(domSelection);
  if (privateSelection)
    privateSelection->AddSelectionListener(this);
  mDomSelectionWeak = do_GetWeakReference(domSelection);
  
  // set up the blink timer
  if (mVisible)
  {
    StartBlinking();
  }
#ifdef IBMBIDI
  mBidiUI = Preferences::GetBool("bidi.browser.ui");
#endif

  return NS_OK;
}

static PRBool
DrawCJKCaret(nsIFrame* aFrame, PRInt32 aOffset)
{
  nsIContent* content = aFrame->GetContent();
  const nsTextFragment* frag = content->GetText();
  if (!frag)
    return PR_FALSE;
  if (aOffset < 0 || PRUint32(aOffset) >= frag->GetLength())
    return PR_FALSE;
  PRUnichar ch = frag->CharAt(aOffset);
  return 0x2e80 <= ch && ch <= 0xd7ff;
}

nsCaret::Metrics nsCaret::ComputeMetrics(nsIFrame* aFrame, PRInt32 aOffset, nscoord aCaretHeight)
{
  // Compute nominal sizes in appunits
  nscoord caretWidth = (aCaretHeight * mCaretAspectRatio) +
                       nsPresContext::CSSPixelsToAppUnits(mCaretWidthCSSPx);

  if (DrawCJKCaret(aFrame, aOffset)) {
    caretWidth += nsPresContext::CSSPixelsToAppUnits(1);
  }
  nscoord bidiIndicatorSize = nsPresContext::CSSPixelsToAppUnits(kMinBidiIndicatorPixels);
  bidiIndicatorSize = NS_MAX(caretWidth, bidiIndicatorSize);

  // Round them to device pixels. Always round down, except that anything
  // between 0 and 1 goes up to 1 so we don't let the caret disappear.
  PRUint32 tpp = aFrame->PresContext()->AppUnitsPerDevPixel();
  Metrics result;
  result.mCaretWidth = NS_ROUND_BORDER_TO_PIXELS(caretWidth, tpp);
  result.mBidiIndicatorSize = NS_ROUND_BORDER_TO_PIXELS(bidiIndicatorSize, tpp);
  return result;
}

//-----------------------------------------------------------------------------
void nsCaret::Terminate()
{
  // this doesn't erase the caret if it's drawn. Should it? We might not have
  // a good drawing environment during teardown.
  
  KillTimer();
  mBlinkTimer = nsnull;

  // unregiser ourselves as a selection listener
  nsCOMPtr<nsISelection> domSelection = do_QueryReferent(mDomSelectionWeak);
  nsCOMPtr<nsISelectionPrivate> privateSelection(do_QueryInterface(domSelection));
  if (privateSelection)
    privateSelection->RemoveSelectionListener(this);
  mDomSelectionWeak = nsnull;
  mPresShell = nsnull;

  mLastContent = nsnull;
}

//-----------------------------------------------------------------------------
NS_IMPL_ISUPPORTS1(nsCaret, nsISelectionListener)

//-----------------------------------------------------------------------------
nsISelection* nsCaret::GetCaretDOMSelection()
{
  nsCOMPtr<nsISelection> sel(do_QueryReferent(mDomSelectionWeak));
  return sel;  
}

//-----------------------------------------------------------------------------
nsresult nsCaret::SetCaretDOMSelection(nsISelection *aDOMSel)
{
  NS_ENSURE_ARG_POINTER(aDOMSel);
  mDomSelectionWeak = do_GetWeakReference(aDOMSel);   // weak reference to pres shell
  if (mVisible)
  {
    // Stop the caret from blinking in its previous location.
    StopBlinking();
    // Start the caret blinking in the new location.
    StartBlinking();
  }
  return NS_OK;
}


//-----------------------------------------------------------------------------
void nsCaret::SetCaretVisible(PRBool inMakeVisible)
{
  mVisible = inMakeVisible;
  if (mVisible) {
    SetIgnoreUserModify(PR_TRUE);
    StartBlinking();
  } else {
    StopBlinking();
    SetIgnoreUserModify(PR_FALSE);
  }
}


//-----------------------------------------------------------------------------
nsresult nsCaret::GetCaretVisible(PRBool *outMakeVisible)
{
  NS_ENSURE_ARG_POINTER(outMakeVisible);
  *outMakeVisible = (mVisible && MustDrawCaret(PR_TRUE));
  return NS_OK;
}


//-----------------------------------------------------------------------------
void nsCaret::SetCaretReadOnly(PRBool inMakeReadonly)
{
  mReadOnly = inMakeReadonly;
}

nsresult
nsCaret::GetGeometryForFrame(nsIFrame* aFrame,
                             PRInt32   aFrameOffset,
                             nsRect*   aRect,
                             nscoord*  aBidiIndicatorSize)
{
  nsPoint framePos(0, 0);
  nsresult rv = aFrame->GetPointFromOffset(aFrameOffset, &framePos);
  if (NS_FAILED(rv))
    return rv;

  nsIFrame *frame = aFrame->GetContentInsertionFrame();
  NS_ASSERTION(frame, "We should not be in the middle of reflow");
  nscoord baseline = frame->GetCaretBaseline();
  nscoord ascent = 0, descent = 0;
  nsRefPtr<nsFontMetrics> fm;
  nsLayoutUtils::GetFontMetricsForFrame(aFrame, getter_AddRefs(fm));
  NS_ASSERTION(fm, "We should be able to get the font metrics");
  if (fm) {
    ascent = fm->MaxAscent();
    descent = fm->MaxDescent();
  }
  nscoord height = ascent + descent;
  framePos.y = baseline - ascent;
  Metrics caretMetrics = ComputeMetrics(aFrame, aFrameOffset, height);
  *aRect = nsRect(framePos, nsSize(caretMetrics.mCaretWidth, height));

  // Clamp the x-position to be within our scroll frame. If we don't, then it
  // clips us, and we don't appear at all. See bug 335560.
  nsIFrame *scrollFrame =
    nsLayoutUtils::GetClosestFrameOfType(aFrame, nsGkAtoms::scrollFrame);
  if (scrollFrame) {
    // First, use the scrollFrame to get at the scrollable view that we're in.
    nsIScrollableFrame *sf = do_QueryFrame(scrollFrame);
    nsIFrame *scrolled = sf->GetScrolledFrame();
    nsRect caretInScroll = *aRect + aFrame->GetOffsetTo(scrolled);

    // Now see if thet caret extends beyond the view's bounds. If it does,
    // then snap it back, put it as close to the edge as it can.
    nscoord overflow = caretInScroll.XMost() -
      scrolled->GetVisualOverflowRectRelativeToSelf().width;
    if (overflow > 0)
      aRect->x -= overflow;
  }

  if (aBidiIndicatorSize)
    *aBidiIndicatorSize = caretMetrics.mBidiIndicatorSize;

  return NS_OK;
}

nsIFrame* nsCaret::GetGeometry(nsISelection* aSelection, nsRect* aRect,
                               nscoord* aBidiIndicatorSize)
{
  nsCOMPtr<nsIDOMNode> focusNode;
  nsresult rv = aSelection->GetFocusNode(getter_AddRefs(focusNode));
  if (NS_FAILED(rv) || !focusNode)
    return nsnull;

  PRInt32 focusOffset;
  rv = aSelection->GetFocusOffset(&focusOffset);
  if (NS_FAILED(rv))
    return nsnull;
    
  nsCOMPtr<nsIContent> contentNode = do_QueryInterface(focusNode);
  if (!contentNode)
    return nsnull;

  nsRefPtr<nsFrameSelection> frameSelection = GetFrameSelection();
  if (!frameSelection)
    return nsnull;
  PRUint8 bidiLevel = frameSelection->GetCaretBidiLevel();
  nsIFrame* frame;
  PRInt32 frameOffset;
  rv = GetCaretFrameForNodeOffset(contentNode, focusOffset,
                                  frameSelection->GetHint(), bidiLevel,
                                  &frame, &frameOffset);
  if (NS_FAILED(rv) || !frame)
    return nsnull;

  GetGeometryForFrame(frame, frameOffset, aRect, aBidiIndicatorSize);
  return frame;
}

void nsCaret::DrawCaretAfterBriefDelay()
{
  // Make sure readonly caret gets drawn again if it needs to be
  if (!mBlinkTimer) {
    nsresult  err;
    mBlinkTimer = do_CreateInstance("@mozilla.org/timer;1", &err);    
    if (NS_FAILED(err))
      return;
  }    

  mBlinkTimer->InitWithFuncCallback(CaretBlinkCallback, this, 0,
                                    nsITimer::TYPE_ONE_SHOT);
}

void nsCaret::EraseCaret()
{
  if (mDrawn) {
    DrawCaret(PR_TRUE);
    if (mReadOnly && mBlinkRate) {
      // If readonly we don't have a blink timer set, so caret won't
      // be redrawn automatically. We need to force the caret to get
      // redrawn right after the paint
      DrawCaretAfterBriefDelay();
    }
  }
}

void nsCaret::SetVisibilityDuringSelection(PRBool aVisibility) 
{
  mShowDuringSelection = aVisibility;
}

nsresult nsCaret::DrawAtPosition(nsIDOMNode* aNode, PRInt32 aOffset)
{
  NS_ENSURE_ARG(aNode);

  PRUint8 bidiLevel;
  nsRefPtr<nsFrameSelection> frameSelection = GetFrameSelection();
  if (!frameSelection)
    return NS_ERROR_FAILURE;
  bidiLevel = frameSelection->GetCaretBidiLevel();

  // DrawAtPosition is used by consumers who want us to stay drawn where they
  // tell us. Setting mBlinkRate to 0 tells us to not set a timer to erase
  // ourselves, our consumer will take care of that.
  mBlinkRate = 0;

  // XXX we need to do more work here to get the correct hint.
  nsresult rv = DrawAtPositionWithHint(aNode, aOffset,
                                       nsFrameSelection::HINTLEFT,
                                       bidiLevel, PR_TRUE)
    ?  NS_OK : NS_ERROR_FAILURE;
  ToggleDrawnStatus();
  return rv;
}

nsIFrame * nsCaret::GetCaretFrame(PRInt32 *aOffset)
{
  // Return null if we're not drawn to prevent anybody from trying to draw us.
  if (!mDrawn)
    return nsnull;

  // Recompute the frame that we're supposed to draw in to guarantee that
  // we're not going to try to draw into a stale (dead) frame.
  PRInt32 offset;
  nsIFrame *frame = nsnull;
  nsresult rv = GetCaretFrameForNodeOffset(mLastContent, mLastContentOffset,
                                           mLastHint, mLastBidiLevel, &frame,
                                           &offset);
  if (NS_FAILED(rv))
    return nsnull;

  if (aOffset) {
    *aOffset = offset;
  }
  return frame;
}

void nsCaret::InvalidateOutsideCaret()
{
  nsIFrame *frame = GetCaretFrame();

  // Only invalidate if we are not fully contained by our frame's rect.
  if (frame && !frame->GetVisualOverflowRect().Contains(GetCaretRect()))
    InvalidateRects(mCaretRect, GetHookRect(), frame);
}

void nsCaret::UpdateCaretPosition()
{
  // We'll recalculate anyway if we're not drawn right now.
  if (!mDrawn)
    return;

  // A trick! Make the DrawCaret code recalculate the caret's current
  // position.
  mDrawn = PR_FALSE;
  DrawCaret(PR_FALSE);
}

void nsCaret::PaintCaret(nsDisplayListBuilder *aBuilder,
                         nsRenderingContext *aCtx,
                         nsIFrame* aForFrame,
                         const nsPoint &aOffset)
{
  NS_ASSERTION(mDrawn, "The caret shouldn't be drawing");

  const nsRect drawCaretRect = mCaretRect + aOffset;
  PRInt32 contentOffset;

#ifdef DEBUG
  nsIFrame* frame =
#endif
    GetCaretFrame(&contentOffset);
  NS_ASSERTION(frame == aForFrame, "We're referring different frame");
  nscolor foregroundColor = aForFrame->GetCaretColorAt(contentOffset);

  // Only draw the native caret if the foreground color matches that of
  // -moz-fieldtext (the color of the text in a textbox). If it doesn't match
  // we are likely in contenteditable or a custom widget and we risk being hard to see
  // against the background. In that case, fall back to the CSS color.
  nsPresContext* presContext = aForFrame->PresContext();

  if (GetHookRect().IsEmpty() && presContext) {
    nsITheme *theme = presContext->GetTheme();
    if (theme && theme->ThemeSupportsWidget(presContext, aForFrame, NS_THEME_TEXTFIELD_CARET)) {
      nscolor fieldText;
      nsresult rv = LookAndFeel::GetColor(LookAndFeel::eColorID__moz_fieldtext,
                                          &fieldText);
      if (NS_SUCCEEDED(rv) && fieldText == foregroundColor) {
        theme->DrawWidgetBackground(aCtx, aForFrame, NS_THEME_TEXTFIELD_CARET,
                                    drawCaretRect, drawCaretRect);
        return;
      }
    }
  }

  aCtx->SetColor(foregroundColor);
  aCtx->FillRect(drawCaretRect);
  if (!GetHookRect().IsEmpty())
    aCtx->FillRect(GetHookRect() + aOffset);
}


//-----------------------------------------------------------------------------
NS_IMETHODIMP nsCaret::NotifySelectionChanged(nsIDOMDocument *, nsISelection *aDomSel, PRInt16 aReason)
{
  if (aReason & nsISelectionListener::MOUSEUP_REASON)//this wont do
    return NS_OK;

  nsCOMPtr<nsISelection> domSel(do_QueryReferent(mDomSelectionWeak));

  // The same caret is shared amongst the document and any text widgets it
  // may contain. This means that the caret could get notifications from
  // multiple selections.
  //
  // If this notification is for a selection that is not the one the
  // the caret is currently interested in (mDomSelectionWeak), then there
  // is nothing to do!

  if (domSel != aDomSel)
    return NS_OK;

  if (mVisible)
  {
    // Stop the caret from blinking in its previous location.
    StopBlinking();

    // Start the caret blinking in the new location.
    StartBlinking();
  }

  return NS_OK;
}


//-----------------------------------------------------------------------------
void nsCaret::KillTimer()
{
  if (mBlinkTimer)
  {
    mBlinkTimer->Cancel();
  }
}


//-----------------------------------------------------------------------------
nsresult nsCaret::PrimeTimer()
{
  // set up the blink timer
  if (!mReadOnly && mBlinkRate > 0)
  {
    if (!mBlinkTimer) {
      nsresult  err;
      mBlinkTimer = do_CreateInstance("@mozilla.org/timer;1", &err);    
      if (NS_FAILED(err))
        return err;
    }    

    mBlinkTimer->InitWithFuncCallback(CaretBlinkCallback, this, mBlinkRate,
                                      nsITimer::TYPE_REPEATING_SLACK);
  }

  return NS_OK;
}

void nsCaret::InvalidateTextOverflowBlock()
{
  // If the nearest block has a potential 'text-overflow' marker then
  // invalidate it.
  if (mLastContent) {
    nsIFrame* caretFrame = mLastContent->GetPrimaryFrame();
    if (caretFrame) {
      nsIFrame* block = nsLayoutUtils::GetAsBlock(caretFrame) ? caretFrame :
        nsLayoutUtils::FindNearestBlockAncestor(caretFrame);
      if (block) {
        const nsStyleTextReset* style = block->GetStyleTextReset();
        if (style->mTextOverflow.mLeft.mType != NS_STYLE_TEXT_OVERFLOW_CLIP ||
            style->mTextOverflow.mRight.mType != NS_STYLE_TEXT_OVERFLOW_CLIP) {
          block->InvalidateOverflowRect();
        }
      }
    }
  }
}

//-----------------------------------------------------------------------------
void nsCaret::StartBlinking()
{
  InvalidateTextOverflowBlock();

  if (mReadOnly) {
    // Make sure the one draw command we use for a readonly caret isn't
    // done until the selection is set
    DrawCaretAfterBriefDelay();
    return;
  }
  PrimeTimer();

  // If we are currently drawn, then the second call to DrawCaret below will
  // actually erase the caret. That would cause the caret to spend an "off"
  // cycle before it appears, which is not really what we want. This first
  // call to DrawCaret makes sure that the first cycle after a call to
  // StartBlinking is an "on" cycle.
  if (mDrawn)
    DrawCaret(PR_TRUE);

  DrawCaret(PR_TRUE);    // draw it right away
}


//-----------------------------------------------------------------------------
void nsCaret::StopBlinking()
{
  InvalidateTextOverflowBlock();

  if (mDrawn)     // erase the caret if necessary
    DrawCaret(PR_TRUE);

  NS_ASSERTION(!mDrawn, "Caret still drawn after StopBlinking().");
  KillTimer();
}

PRBool
nsCaret::DrawAtPositionWithHint(nsIDOMNode*             aNode,
                                PRInt32                 aOffset,
                                nsFrameSelection::HINT  aFrameHint,
                                PRUint8                 aBidiLevel,
                                PRBool                  aInvalidate)
{
  nsCOMPtr<nsIContent> contentNode = do_QueryInterface(aNode);
  if (!contentNode)
    return PR_FALSE;

  nsIFrame* theFrame = nsnull;
  PRInt32   theFrameOffset = 0;

  nsresult rv = GetCaretFrameForNodeOffset(contentNode, aOffset, aFrameHint, aBidiLevel,
                                           &theFrame, &theFrameOffset);
  if (NS_FAILED(rv) || !theFrame)
    return PR_FALSE;

  // now we have a frame, check whether it's appropriate to show the caret here
  const nsStyleUserInterface* userinterface = theFrame->GetStyleUserInterface();
  if ((!mIgnoreUserModify &&
       userinterface->mUserModify == NS_STYLE_USER_MODIFY_READ_ONLY) ||
      (userinterface->mUserInput == NS_STYLE_USER_INPUT_NONE) ||
      (userinterface->mUserInput == NS_STYLE_USER_INPUT_DISABLED))
  {
    return PR_FALSE;
  }  

  if (!mDrawn)
  {
    // save stuff so we can figure out what frame we're in later.
    mLastContent = contentNode;
    mLastContentOffset = aOffset;
    mLastHint = aFrameHint;
    mLastBidiLevel = aBidiLevel;

    // If there has been a reflow, set the caret Bidi level to the level of the current frame
    if (aBidiLevel & BIDI_LEVEL_UNDEFINED) {
      nsRefPtr<nsFrameSelection> frameSelection = GetFrameSelection();
      if (!frameSelection)
        return PR_FALSE;
      frameSelection->SetCaretBidiLevel(NS_GET_EMBEDDING_LEVEL(theFrame));
    }

    // Only update the caret's rect when we're not currently drawn.
    if (!UpdateCaretRects(theFrame, theFrameOffset))
      return PR_FALSE;
  }

  if (aInvalidate)
    InvalidateRects(mCaretRect, mHookRect, theFrame);

  return PR_TRUE;
}

nsresult 
nsCaret::GetCaretFrameForNodeOffset(nsIContent*             aContentNode,
                                    PRInt32                 aOffset,
                                    nsFrameSelection::HINT aFrameHint,
                                    PRUint8                 aBidiLevel,
                                    nsIFrame**              aReturnFrame,
                                    PRInt32*                aReturnOffset)
{

  //get frame selection and find out what frame to use...
  nsCOMPtr<nsIPresShell> presShell = do_QueryReferent(mPresShell);
  if (!presShell)
    return NS_ERROR_FAILURE;

  if (!aContentNode || !aContentNode->IsInDoc() ||
      presShell->GetDocument() != aContentNode->GetCurrentDoc())
    return NS_ERROR_FAILURE;

  nsRefPtr<nsFrameSelection> frameSelection = GetFrameSelection();
  if (!frameSelection)
    return NS_ERROR_FAILURE;

  nsIFrame* theFrame = nsnull;
  PRInt32   theFrameOffset = 0;

  theFrame = frameSelection->GetFrameForNodeOffset(aContentNode, aOffset,
                                                   aFrameHint, &theFrameOffset);
  if (!theFrame)
    return NS_ERROR_FAILURE;

  // if theFrame is after a text frame that's logically at the end of the line
  // (e.g. if theFrame is a <br> frame), then put the caret at the end of
  // that text frame instead. This way, the caret will be positioned as if
  // trailing whitespace was not trimmed.
  AdjustCaretFrameForLineEnd(&theFrame, &theFrameOffset);
  
  // Mamdouh : modification of the caret to work at rtl and ltr with Bidi
  //
  // Direction Style from this->GetStyleData()
  // now in (visibility->mDirection)
  // ------------------
  // NS_STYLE_DIRECTION_LTR : LTR or Default
  // NS_STYLE_DIRECTION_RTL
  // NS_STYLE_DIRECTION_INHERIT
  if (mBidiUI)
  {
    // If there has been a reflow, take the caret Bidi level to be the level of the current frame
    if (aBidiLevel & BIDI_LEVEL_UNDEFINED)
      aBidiLevel = NS_GET_EMBEDDING_LEVEL(theFrame);

    PRInt32 start;
    PRInt32 end;
    nsIFrame* frameBefore;
    nsIFrame* frameAfter;
    PRUint8 levelBefore;     // Bidi level of the character before the caret
    PRUint8 levelAfter;      // Bidi level of the character after the caret

    theFrame->GetOffsets(start, end);
    if (start == 0 || end == 0 || start == theFrameOffset || end == theFrameOffset)
    {
      nsPrevNextBidiLevels levels = frameSelection->
        GetPrevNextBidiLevels(aContentNode, aOffset, PR_FALSE);
    
      /* Boundary condition, we need to know the Bidi levels of the characters before and after the caret */
      if (levels.mFrameBefore || levels.mFrameAfter)
      {
        frameBefore = levels.mFrameBefore;
        frameAfter = levels.mFrameAfter;
        levelBefore = levels.mLevelBefore;
        levelAfter = levels.mLevelAfter;

        if ((levelBefore != levelAfter) || (aBidiLevel != levelBefore))
        {
          aBidiLevel = NS_MAX(aBidiLevel, NS_MIN(levelBefore, levelAfter));                                  // rule c3
          aBidiLevel = NS_MIN(aBidiLevel, NS_MAX(levelBefore, levelAfter));                                  // rule c4
          if (aBidiLevel == levelBefore                                                                      // rule c1
              || (aBidiLevel > levelBefore && aBidiLevel < levelAfter && !((aBidiLevel ^ levelBefore) & 1))    // rule c5
              || (aBidiLevel < levelBefore && aBidiLevel > levelAfter && !((aBidiLevel ^ levelBefore) & 1)))  // rule c9
          {
            if (theFrame != frameBefore)
            {
              if (frameBefore) // if there is a frameBefore, move into it
              {
                theFrame = frameBefore;
                theFrame->GetOffsets(start, end);
                theFrameOffset = end;
              }
              else 
              {
                // if there is no frameBefore, we must be at the beginning of the line
                // so we stay with the current frame.
                // Exception: when the first frame on the line has a different Bidi level from the paragraph level, there is no
                // real frame for the caret to be in. We have to find the visually first frame on the line.
                PRUint8 baseLevel = NS_GET_BASE_LEVEL(frameAfter);
                if (baseLevel != levelAfter)
                {
                  nsPeekOffsetStruct pos;
                  pos.SetData(eSelectBeginLine, eDirPrevious, 0, 0, PR_FALSE, PR_TRUE, PR_FALSE, PR_TRUE);
                  if (NS_SUCCEEDED(frameAfter->PeekOffset(&pos))) {
                    theFrame = pos.mResultFrame;
                    theFrameOffset = pos.mContentOffset;
                  }
                }
              }
            }
          }
          else if (aBidiLevel == levelAfter                                                                     // rule c2
                   || (aBidiLevel > levelBefore && aBidiLevel < levelAfter && !((aBidiLevel ^ levelAfter) & 1))   // rule c6
                   || (aBidiLevel < levelBefore && aBidiLevel > levelAfter && !((aBidiLevel ^ levelAfter) & 1)))  // rule c10
          {
            if (theFrame != frameAfter)
            {
              if (frameAfter)
              {
                // if there is a frameAfter, move into it
                theFrame = frameAfter;
                theFrame->GetOffsets(start, end);
                theFrameOffset = start;
              }
              else 
              {
                // if there is no frameAfter, we must be at the end of the line
                // so we stay with the current frame.
                // Exception: when the last frame on the line has a different Bidi level from the paragraph level, there is no
                // real frame for the caret to be in. We have to find the visually last frame on the line.
                PRUint8 baseLevel = NS_GET_BASE_LEVEL(frameBefore);
                if (baseLevel != levelBefore)
                {
                  nsPeekOffsetStruct pos;
                  pos.SetData(eSelectEndLine, eDirNext, 0, 0, PR_FALSE, PR_TRUE, PR_FALSE, PR_TRUE);
                  if (NS_SUCCEEDED(frameBefore->PeekOffset(&pos))) {
                    theFrame = pos.mResultFrame;
                    theFrameOffset = pos.mContentOffset;
                  }
                }
              }
            }
          }
          else if (aBidiLevel > levelBefore && aBidiLevel < levelAfter  // rule c7/8
                   && !((levelBefore ^ levelAfter) & 1)                 // before and after have the same parity
                   && ((aBidiLevel ^ levelAfter) & 1))                  // caret has different parity
          {
            if (NS_SUCCEEDED(frameSelection->GetFrameFromLevel(frameAfter, eDirNext, aBidiLevel, &theFrame)))
            {
              theFrame->GetOffsets(start, end);
              levelAfter = NS_GET_EMBEDDING_LEVEL(theFrame);
              if (aBidiLevel & 1) // c8: caret to the right of the rightmost character
                theFrameOffset = (levelAfter & 1) ? start : end;
              else               // c7: caret to the left of the leftmost character
                theFrameOffset = (levelAfter & 1) ? end : start;
            }
          }
          else if (aBidiLevel < levelBefore && aBidiLevel > levelAfter  // rule c11/12
                   && !((levelBefore ^ levelAfter) & 1)                 // before and after have the same parity
                   && ((aBidiLevel ^ levelAfter) & 1))                  // caret has different parity
          {
            if (NS_SUCCEEDED(frameSelection->GetFrameFromLevel(frameBefore, eDirPrevious, aBidiLevel, &theFrame)))
            {
              theFrame->GetOffsets(start, end);
              levelBefore = NS_GET_EMBEDDING_LEVEL(theFrame);
              if (aBidiLevel & 1) // c12: caret to the left of the leftmost character
                theFrameOffset = (levelBefore & 1) ? end : start;
              else               // c11: caret to the right of the rightmost character
                theFrameOffset = (levelBefore & 1) ? start : end;
            }
          }   
        }
      }
    }
  }

  NS_ASSERTION(!theFrame || theFrame->PresContext()->PresShell() == presShell,
               "caret frame is in wrong document");
  *aReturnFrame = theFrame;
  *aReturnOffset = theFrameOffset;
  return NS_OK;
}

nsresult nsCaret::CheckCaretDrawingState()
{
  if (mDrawn) {
    // The caret is drawn; if it shouldn't be, erase it.
    if (!mVisible || !MustDrawCaret(PR_TRUE))
      EraseCaret();
  }
  else
  {
    // The caret is not drawn; if it should be, draw it.
    if (mPendingDraw && (mVisible && MustDrawCaret(PR_TRUE)))
      DrawCaret(PR_TRUE);
  }
  return NS_OK;
}

/*-----------------------------------------------------------------------------

  MustDrawCaret
  
  Find out if we need to do any caret drawing. This returns true if
  either:
  a) The caret has been drawn, and we need to erase it.
  b) The caret is not drawn, and the selection is collapsed.
  c) The caret is not hidden due to open XUL popups
     (see IsMenuPopupHidingCaret()).
  
----------------------------------------------------------------------------- */
PRBool nsCaret::MustDrawCaret(PRBool aIgnoreDrawnState)
{
  if (!aIgnoreDrawnState && mDrawn)
    return PR_TRUE;

  nsCOMPtr<nsISelection> domSelection = do_QueryReferent(mDomSelectionWeak);
  if (!domSelection)
    return PR_FALSE;

  PRBool isCollapsed;
  if (NS_FAILED(domSelection->GetIsCollapsed(&isCollapsed)))
    return PR_FALSE;

  if (mShowDuringSelection)
    return PR_TRUE;      // show the caret even in selections

  if (IsMenuPopupHidingCaret())
    return PR_FALSE;

  return isCollapsed;
}

PRBool nsCaret::IsMenuPopupHidingCaret()
{
#ifdef MOZ_XUL
  // Check if there are open popups.
  nsXULPopupManager *popMgr = nsXULPopupManager::GetInstance();
  nsTArray<nsIFrame*> popups = popMgr->GetVisiblePopups();

  if (popups.Length() == 0)
    return PR_FALSE; // No popups, so caret can't be hidden by them.

  // Get the selection focus content, that's where the caret would 
  // go if it was drawn.
  nsCOMPtr<nsIDOMNode> node;
  nsCOMPtr<nsISelection> domSelection = do_QueryReferent(mDomSelectionWeak);
  if (!domSelection)
    return PR_TRUE; // No selection/caret to draw.
  domSelection->GetFocusNode(getter_AddRefs(node));
  if (!node)
    return PR_TRUE; // No selection/caret to draw.
  nsCOMPtr<nsIContent> caretContent = do_QueryInterface(node);
  if (!caretContent)
    return PR_TRUE; // No selection/caret to draw.

  // If there's a menu popup open before the popup with
  // the caret, don't show the caret.
  for (PRUint32 i=0; i<popups.Length(); i++) {
    nsMenuPopupFrame* popupFrame = static_cast<nsMenuPopupFrame*>(popups[i]);
    nsIContent* popupContent = popupFrame->GetContent();

    if (nsContentUtils::ContentIsDescendantOf(caretContent, popupContent)) {
      // The caret is in this popup. There were no menu popups before this
      // popup, so don't hide the caret.
      return PR_FALSE;
    }

    if (popupFrame->PopupType() == ePopupTypeMenu && !popupFrame->IsContextMenu()) {
      // This is an open menu popup. It does not contain the caret (else we'd
      // have returned above). Even if the caret is in a subsequent popup,
      // or another document/frame, it should be hidden.
      return PR_TRUE;
    }
  }
#endif

  // There are no open menu popups, no need to hide the caret.
  return PR_FALSE;
}

void nsCaret::DrawCaret(PRBool aInvalidate)
{
  // Do we need to draw the caret at all?
  if (!MustDrawCaret(PR_FALSE))
    return;
  
  // Can we draw the caret now?
  nsCOMPtr<nsIPresShell> presShell = do_QueryReferent(mPresShell);
  NS_ENSURE_TRUE(presShell, /**/);
  {
    if (presShell->IsPaintingSuppressed())
    {
      if (!mDrawn)
        mPendingDraw = PR_TRUE;

      // PresShell::UnsuppressAndInvalidate() will call CheckCaretDrawingState()
      // to get us drawn.
      return;
    }
  }

  nsCOMPtr<nsIDOMNode> node;
  PRInt32 offset;
  nsFrameSelection::HINT hint;
  PRUint8 bidiLevel;

  if (!mDrawn)
  {
    nsCOMPtr<nsISelection> domSelection = do_QueryReferent(mDomSelectionWeak);
    nsCOMPtr<nsISelectionPrivate> privateSelection(do_QueryInterface(domSelection));
    if (!privateSelection) return;
    
    PRBool isCollapsed = PR_FALSE;
    domSelection->GetIsCollapsed(&isCollapsed);
    if (!mShowDuringSelection && !isCollapsed)
      return;

    PRBool hintRight;
    privateSelection->GetInterlinePosition(&hintRight);//translate hint.
    hint = hintRight ? nsFrameSelection::HINTRIGHT : nsFrameSelection::HINTLEFT;

    // get the node and offset, which is where we want the caret to draw
    domSelection->GetFocusNode(getter_AddRefs(node));
    if (!node)
      return;
    
    if (NS_FAILED(domSelection->GetFocusOffset(&offset)))
      return;

    nsRefPtr<nsFrameSelection> frameSelection = GetFrameSelection();
    if (!frameSelection)
      return;

    bidiLevel = frameSelection->GetCaretBidiLevel();
    mPendingDraw = PR_FALSE;
  }
  else
  {
    if (!mLastContent)
    {
      mDrawn = PR_FALSE;
      return;
    }
    if (!mLastContent->IsInDoc() ||
        presShell->GetDocument() != mLastContent->GetCurrentDoc())
    {
      mLastContent = nsnull;
      mDrawn = PR_FALSE;
      return;
    }
    node = do_QueryInterface(mLastContent);
    offset = mLastContentOffset;
    hint = mLastHint;
    bidiLevel = mLastBidiLevel;
  }

  DrawAtPositionWithHint(node, offset, hint, bidiLevel, aInvalidate);
  ToggleDrawnStatus();
}

PRBool
nsCaret::UpdateCaretRects(nsIFrame* aFrame, PRInt32 aFrameOffset)
{
  NS_ASSERTION(aFrame, "Should have a frame here");

  nscoord bidiIndicatorSize;
  nsresult rv =
    GetGeometryForFrame(aFrame, aFrameOffset, &mCaretRect, &bidiIndicatorSize);
  if (NS_FAILED(rv)) {
    return PR_FALSE;
  }

  // on RTL frames the right edge of mCaretRect must be equal to framePos
  const nsStyleVisibility* vis = aFrame->GetStyleVisibility();
  if (NS_STYLE_DIRECTION_RTL == vis->mDirection)
    mCaretRect.x -= mCaretRect.width;

#ifdef IBMBIDI
  mHookRect.SetEmpty();

  // Simon -- make a hook to draw to the left or right of the caret to show keyboard language direction
  PRBool isCaretRTL = PR_FALSE;
  nsIBidiKeyboard* bidiKeyboard = nsContentUtils::GetBidiKeyboard();
  // if bidiKeyboard->IsLangRTL() fails, there is no way to tell the
  // keyboard direction, or the user has no right-to-left keyboard
  // installed, so we never draw the hook.
  if (bidiKeyboard && NS_SUCCEEDED(bidiKeyboard->IsLangRTL(&isCaretRTL)) &&
      mBidiUI) {
    if (isCaretRTL != mKeyboardRTL) {
      /* if the caret bidi level and the keyboard language direction are not in
       * synch, the keyboard language must have been changed by the
       * user, and if the caret is in a boundary condition (between left-to-right and
       * right-to-left characters) it may have to change position to
       * reflect the location in which the next character typed will
       * appear. We will call |SelectionLanguageChange| and exit
       * without drawing the caret in the old position.
       */ 
      mKeyboardRTL = isCaretRTL;
      nsCOMPtr<nsISelection> domSelection = do_QueryReferent(mDomSelectionWeak);
      if (!domSelection ||
          NS_SUCCEEDED(domSelection->SelectionLanguageChange(mKeyboardRTL)))
        return PR_FALSE;
    }
    // If keyboard language is RTL, draw the hook on the left; if LTR, to the right
    // The height of the hook rectangle is the same as the width of the caret
    // rectangle.
    mHookRect.SetRect(mCaretRect.x + ((isCaretRTL) ?
                      bidiIndicatorSize * -1 :
                      mCaretRect.width),
                      mCaretRect.y + bidiIndicatorSize,
                      bidiIndicatorSize,
                      mCaretRect.width);
  }
#endif //IBMBIDI
  return PR_TRUE;
}

// static
void nsCaret::InvalidateRects(const nsRect &aRect, const nsRect &aHook,
                              nsIFrame *aFrame)
{
  NS_ASSERTION(aFrame, "Must have a frame to invalidate");
  nsRect rect;
  rect.UnionRect(aRect, aHook);
  aFrame->Invalidate(rect);
}

//-----------------------------------------------------------------------------
/* static */
void nsCaret::CaretBlinkCallback(nsITimer *aTimer, void *aClosure)
{
  nsCaret   *theCaret = reinterpret_cast<nsCaret*>(aClosure);
  if (!theCaret) return;
  
  theCaret->DrawCaret(PR_TRUE);
}


//-----------------------------------------------------------------------------
already_AddRefed<nsFrameSelection>
nsCaret::GetFrameSelection()
{
  nsCOMPtr<nsISelectionPrivate> privateSelection(do_QueryReferent(mDomSelectionWeak));
  if (!privateSelection)
    return nsnull;
  nsFrameSelection* frameSelection = nsnull;
  privateSelection->GetFrameSelection(&frameSelection);
  return frameSelection;
}

void
nsCaret::SetIgnoreUserModify(PRBool aIgnoreUserModify)
{
  if (!aIgnoreUserModify && mIgnoreUserModify && mDrawn) {
    // We're turning off mIgnoreUserModify. If the caret's drawn
    // in a read-only node we must erase it, else the next call
    // to DrawCaret() won't erase the old caret, due to the new
    // mIgnoreUserModify value.
    nsIFrame *frame = GetCaretFrame();
    if (frame) {
      const nsStyleUserInterface* userinterface = frame->GetStyleUserInterface();
      if (userinterface->mUserModify == NS_STYLE_USER_MODIFY_READ_ONLY) {
        StopBlinking();
      }
    }
  }
  mIgnoreUserModify = aIgnoreUserModify;
}
