/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* ***** 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
 * Mozilla Foundation.
 * Portions created by the Initial Developer are Copyright (C) 2010
 * the Initial Developer. All Rights Reserved.
 *
 * Contributor(s):
 *   Alexander Surkov <surkov.alexander@gmail.com> (original author)
 *
 * 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 ***** */

#include "nsEventShell.h"

#include "nsAccUtils.h"
#include "nsCoreUtils.h"
#include "nsDocAccessible.h"

#include "NotificationController.h"

#include "nsAccessibilityService.h"
#include "nsDocAccessible.h"

////////////////////////////////////////////////////////////////////////////////
// NotificationCollector
////////////////////////////////////////////////////////////////////////////////

NotificationController::NotificationController(nsDocAccessible* aDocument,
                                               nsIPresShell* aPresShell) :
  mObservingState(eNotObservingRefresh), mDocument(aDocument),
  mPresShell(aPresShell)
{
}

NotificationController::~NotificationController()
{
  NS_ASSERTION(!mDocument, "Controller wasn't shutdown properly!");
  if (mDocument)
    Shutdown();
}

////////////////////////////////////////////////////////////////////////////////
// NotificationCollector: AddRef/Release and cycle collection

NS_IMPL_ADDREF(NotificationController)
NS_IMPL_RELEASE(NotificationController)

NS_IMPL_CYCLE_COLLECTION_CLASS(NotificationController)

NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN_NATIVE(NotificationController)
  tmp->Shutdown();
NS_IMPL_CYCLE_COLLECTION_UNLINK_END

NS_IMPL_CYCLE_COLLECTION_TRAVERSE_NATIVE_BEGIN(NotificationController)
  NS_CYCLE_COLLECTION_NOTE_EDGE_NAME(cb, "mDocument");
  cb.NoteXPCOMChild(static_cast<nsIAccessible*>(tmp->mDocument.get()));
  NS_IMPL_CYCLE_COLLECTION_TRAVERSE_NSTARRAY_MEMBER(mContentInsertions,
                                                    ContentInsertion)
  NS_IMPL_CYCLE_COLLECTION_TRAVERSE_NSTARRAY_MEMBER(mEvents, AccEvent)
NS_IMPL_CYCLE_COLLECTION_TRAVERSE_END

NS_IMPL_CYCLE_COLLECTION_ROOT_NATIVE(NotificationController, AddRef)
NS_IMPL_CYCLE_COLLECTION_UNROOT_NATIVE(NotificationController, Release)

////////////////////////////////////////////////////////////////////////////////
// NotificationCollector: public

void
NotificationController::Shutdown()
{
  if (mObservingState != eNotObservingRefresh &&
      mPresShell->RemoveRefreshObserver(this, Flush_Display)) {
    mObservingState = eNotObservingRefresh;
  }

  mDocument = nsnull;
  mPresShell = nsnull;
  mContentInsertions.Clear();
  mNotifications.Clear();
  mEvents.Clear();
}

void
NotificationController::QueueEvent(AccEvent* aEvent)
{
  if (!mEvents.AppendElement(aEvent))
    return;

  // Filter events.
  CoalesceEvents();

  // Associate text change with hide event if it wasn't stolen from hiding
  // siblings during coalescence.
  AccMutationEvent* showOrHideEvent = downcast_accEvent(aEvent);
  if (showOrHideEvent && !showOrHideEvent->mTextChangeEvent)
    CreateTextChangeEventFor(showOrHideEvent);

  ScheduleProcessing();
}

void
NotificationController::ScheduleContentInsertion(nsAccessible* aContainer,
                                                 nsIContent* aStartChildNode,
                                                 nsIContent* aEndChildNode)
{
  nsRefPtr<ContentInsertion> insertion =
    new ContentInsertion(mDocument, aContainer, aStartChildNode, aEndChildNode);

  if (insertion && mContentInsertions.AppendElement(insertion))
    ScheduleProcessing();
}

////////////////////////////////////////////////////////////////////////////////
// NotificationCollector: protected

void
NotificationController::ScheduleProcessing()
{
  // If notification flush isn't planed yet start notification flush
  // asynchronously (after style and layout).
  if (mObservingState == eNotObservingRefresh) {
    if (mPresShell->AddRefreshObserver(this, Flush_Display))
      mObservingState = eRefreshObserving;
  }
}

bool
NotificationController::IsUpdatePending()
{
  nsCOMPtr<nsIPresShell_MOZILLA_2_0_BRANCH2> presShell =
    do_QueryInterface(mPresShell);
  return presShell->IsLayoutFlushObserver() ||
    mObservingState == eRefreshProcessingForUpdate ||
    mContentInsertions.Length() != 0 || mNotifications.Length() != 0;
}

////////////////////////////////////////////////////////////////////////////////
// NotificationCollector: private

void
NotificationController::WillRefresh(mozilla::TimeStamp aTime)
{
  // If the document accessible that notification collector was created for is
  // now shut down, don't process notifications anymore.
  NS_ASSERTION(mDocument,
               "The document was shut down while refresh observer is attached!");
  if (!mDocument)
    return;

  // Any generic notifications should be queued if we're processing content
  // insertions or generic notifications.
  mObservingState = eRefreshProcessingForUpdate;

  // Process content inserted notifications to update the tree. Process other
  // notifications like DOM events and then flush event queue. If any new
  // notifications are queued during this processing then they will be processed
  // on next refresh. If notification processing queues up new events then they
  // are processed in this refresh. If events processing queues up new events
  // then new events are processed on next refresh.
  // Note: notification processing or event handling may shut down the owning
  // document accessible.

  // Process only currently queued content inserted notifications.
  nsTArray<nsRefPtr<ContentInsertion> > contentInsertions;
  contentInsertions.SwapElements(mContentInsertions);

  PRUint32 insertionCount = contentInsertions.Length();
  for (PRUint32 idx = 0; idx < insertionCount; idx++) {
    contentInsertions[idx]->Process();
    if (!mDocument)
      return;
  }

  // Process only currently queued generic notifications.
  nsTArray < nsRefPtr<Notification> > notifications;
  notifications.SwapElements(mNotifications);

  PRUint32 notificationCount = notifications.Length();
  for (PRUint32 idx = 0; idx < notificationCount; idx++) {
    notifications[idx]->Process();
    if (!mDocument)
      return;
  }

  // If a generic notification occurs after this point then we may be allowed to
  // process it synchronously.
  mObservingState = eRefreshObserving;

  // Process only currently queued events.
  nsTArray<nsRefPtr<AccEvent> > events;
  events.SwapElements(mEvents);

  PRUint32 eventCount = events.Length();
  for (PRUint32 idx = 0; idx < eventCount; idx++) {
    AccEvent* accEvent = events[idx];
    if (accEvent->mEventRule != AccEvent::eDoNotEmit) {
      mDocument->ProcessPendingEvent(accEvent);

      AccMutationEvent* showOrhideEvent = downcast_accEvent(accEvent);
      if (showOrhideEvent) {
        if (showOrhideEvent->mTextChangeEvent)
          mDocument->ProcessPendingEvent(showOrhideEvent->mTextChangeEvent);
      }
    }
    if (!mDocument)
      return;
  }

  // Stop further processing if there are no newly queued insertions,
  // notifications or events.
  if (mContentInsertions.Length() == 0 && mNotifications.Length() == 0 &&
      mEvents.Length() == 0 &&
      mPresShell->RemoveRefreshObserver(this, Flush_Display)) {
    mObservingState = eNotObservingRefresh;
  }
}

////////////////////////////////////////////////////////////////////////////////
// NotificationController: event queue

void
NotificationController::CoalesceEvents()
{
  PRUint32 numQueuedEvents = mEvents.Length();
  PRInt32 tail = numQueuedEvents - 1;
  AccEvent* tailEvent = mEvents[tail];

  // No node means this is application accessible (which can be a subject
  // of reorder events), we do not coalesce events for it currently.
  if (!tailEvent->mNode)
    return;

  switch(tailEvent->mEventRule) {
    case AccEvent::eCoalesceFromSameSubtree:
    {
      for (PRInt32 index = tail - 1; index >= 0; index--) {
        AccEvent* thisEvent = mEvents[index];

        if (thisEvent->mEventType != tailEvent->mEventType)
          continue; // Different type

        // Skip event for application accessible since no coalescence for it
        // is supported. Ignore events from different documents since we don't
        // coalesce them.
        if (!thisEvent->mNode ||
            thisEvent->mNode->GetOwnerDoc() != tailEvent->mNode->GetOwnerDoc())
          continue;

        // Coalesce earlier event for the same target.
        if (thisEvent->mNode == tailEvent->mNode) {
          thisEvent->mEventRule = AccEvent::eDoNotEmit;
          return;
        }

        // If event queue contains an event of the same type and having target
        // that is sibling of target of newly appended event then apply its
        // event rule to the newly appended event.

        // Coalesce hide and show events for sibling targets.
        if (tailEvent->mEventType == nsIAccessibleEvent::EVENT_HIDE) {
          AccHideEvent* tailHideEvent = downcast_accEvent(tailEvent);
          AccHideEvent* thisHideEvent = downcast_accEvent(thisEvent);
          if (thisHideEvent->mParent == tailHideEvent->mParent) {
            tailEvent->mEventRule = thisEvent->mEventRule;

            // Coalesce text change events for hide events.
            if (tailEvent->mEventRule != AccEvent::eDoNotEmit)
              CoalesceTextChangeEventsFor(tailHideEvent, thisHideEvent);

            return;
          }
        } else if (tailEvent->mEventType == nsIAccessibleEvent::EVENT_SHOW) {
          if (thisEvent->mAccessible->GetParent() ==
              tailEvent->mAccessible->GetParent()) {
            tailEvent->mEventRule = thisEvent->mEventRule;

            // Coalesce text change events for show events.
            if (tailEvent->mEventRule != AccEvent::eDoNotEmit) {
              AccShowEvent* tailShowEvent = downcast_accEvent(tailEvent);
              AccShowEvent* thisShowEvent = downcast_accEvent(thisEvent);
              CoalesceTextChangeEventsFor(tailShowEvent, thisShowEvent);
            }

            return;
          }
        }

        // Ignore events unattached from DOM since we don't coalesce them.
        if (!thisEvent->mNode->IsInDoc())
          continue;

        // Coalesce events by sibling targets (this is a case for reorder
        // events).
        if (thisEvent->mNode->GetNodeParent() ==
            tailEvent->mNode->GetNodeParent()) {
          tailEvent->mEventRule = thisEvent->mEventRule;
          return;
        }

        // This and tail events can be anywhere in the tree, make assumptions
        // for mutation events.

        // Coalesce tail event if tail node is descendant of this node. Stop
        // processing if tail event is coalesced since all possible descendants
        // of this node was coalesced before.
        // Note: more older hide event target (thisNode) can't contain recent
        // hide event target (tailNode), i.e. be ancestor of tailNode. Skip
        // this check for hide events.
        if (tailEvent->mEventType != nsIAccessibleEvent::EVENT_HIDE &&
            nsCoreUtils::IsAncestorOf(thisEvent->mNode, tailEvent->mNode)) {
          tailEvent->mEventRule = AccEvent::eDoNotEmit;
          return;
        }

        // If this node is a descendant of tail node then coalesce this event,
        // check other events in the queue. Do not emit thisEvent, also apply
        // this result to sibling nodes of thisNode.
        if (nsCoreUtils::IsAncestorOf(tailEvent->mNode, thisEvent->mNode)) {
          thisEvent->mEventRule = AccEvent::eDoNotEmit;
          ApplyToSiblings(0, index, thisEvent->mEventType,
                          thisEvent->mNode, AccEvent::eDoNotEmit);
          continue;
        }

      } // for (index)

    } break; // case eCoalesceFromSameSubtree

    case AccEvent::eCoalesceFromSameDocument:
    {
      // Used for focus event, coalesce more older event since focus event
      // for accessible can be duplicated by event for its document, we are
      // interested in focus event for accessible.
      for (PRInt32 index = tail - 1; index >= 0; index--) {
        AccEvent* thisEvent = mEvents[index];
        if (thisEvent->mEventType == tailEvent->mEventType &&
            thisEvent->mEventRule == tailEvent->mEventRule &&
            thisEvent->GetDocAccessible() == tailEvent->GetDocAccessible()) {
          thisEvent->mEventRule = AccEvent::eDoNotEmit;
          return;
        }
      }
    } break; // case eCoalesceFromSameDocument

    case AccEvent::eRemoveDupes:
    {
      // Check for repeat events, coalesce newly appended event by more older
      // event.
      for (PRInt32 index = tail - 1; index >= 0; index--) {
        AccEvent* accEvent = mEvents[index];
        if (accEvent->mEventType == tailEvent->mEventType &&
            accEvent->mEventRule == tailEvent->mEventRule &&
            accEvent->mNode == tailEvent->mNode) {
          tailEvent->mEventRule = AccEvent::eDoNotEmit;
          return;
        }
      }
    } break; // case eRemoveDupes

    default:
      break; // case eAllowDupes, eDoNotEmit
  } // switch
}

void
NotificationController::ApplyToSiblings(PRUint32 aStart, PRUint32 aEnd,
                                        PRUint32 aEventType, nsINode* aNode,
                                        AccEvent::EEventRule aEventRule)
{
  for (PRUint32 index = aStart; index < aEnd; index ++) {
    AccEvent* accEvent = mEvents[index];
    if (accEvent->mEventType == aEventType &&
        accEvent->mEventRule != AccEvent::eDoNotEmit && accEvent->mNode &&
        accEvent->mNode->GetNodeParent() == aNode->GetNodeParent()) {
      accEvent->mEventRule = aEventRule;
    }
  }
}

void
NotificationController::CoalesceTextChangeEventsFor(AccHideEvent* aTailEvent,
                                                    AccHideEvent* aThisEvent)
{
  // XXX: we need a way to ignore SplitNode and JoinNode() when they do not
  // affect the text within the hypertext.

  AccTextChangeEvent* textEvent = aThisEvent->mTextChangeEvent;
  if (!textEvent)
    return;

  if (aThisEvent->mNextSibling == aTailEvent->mAccessible) {
    aTailEvent->mAccessible->AppendTextTo(textEvent->mModifiedText,
                                          0, PR_UINT32_MAX);

  } else if (aThisEvent->mPrevSibling == aTailEvent->mAccessible) {
    PRUint32 oldLen = textEvent->GetLength();
    aTailEvent->mAccessible->AppendTextTo(textEvent->mModifiedText,
                                          0, PR_UINT32_MAX);
    textEvent->mStart -= textEvent->GetLength() - oldLen;
  }

  aTailEvent->mTextChangeEvent.swap(aThisEvent->mTextChangeEvent);
}

void
NotificationController::CoalesceTextChangeEventsFor(AccShowEvent* aTailEvent,
                                                    AccShowEvent* aThisEvent)
{
  AccTextChangeEvent* textEvent = aThisEvent->mTextChangeEvent;
  if (!textEvent)
    return;

  if (aTailEvent->mAccessible->GetIndexInParent() ==
      aThisEvent->mAccessible->GetIndexInParent() + 1) {
    // If tail target was inserted after this target, i.e. tail target is next
    // sibling of this target.
    aTailEvent->mAccessible->AppendTextTo(textEvent->mModifiedText,
                                          0, PR_UINT32_MAX);

  } else if (aTailEvent->mAccessible->GetIndexInParent() ==
             aThisEvent->mAccessible->GetIndexInParent() -1) {
    // If tail target was inserted before this target, i.e. tail target is
    // previous sibling of this target.
    nsAutoString startText;
    aTailEvent->mAccessible->AppendTextTo(startText, 0, PR_UINT32_MAX);
    textEvent->mModifiedText = startText + textEvent->mModifiedText;
    textEvent->mStart -= startText.Length();
  }

  aTailEvent->mTextChangeEvent.swap(aThisEvent->mTextChangeEvent);
}

void
NotificationController::CreateTextChangeEventFor(AccMutationEvent* aEvent)
{
  nsRefPtr<nsHyperTextAccessible> textAccessible = do_QueryObject(
    GetAccService()->GetContainerAccessible(aEvent->mNode,
                                            aEvent->mAccessible->GetWeakShell()));
  if (!textAccessible)
    return;

  // Don't fire event for the first html:br in an editor.
  if (aEvent->mAccessible->Role() == nsIAccessibleRole::ROLE_WHITESPACE) {
    nsCOMPtr<nsIEditor> editor;
    textAccessible->GetAssociatedEditor(getter_AddRefs(editor));
    if (editor) {
      PRBool isEmpty = PR_FALSE;
      editor->GetDocumentIsEmpty(&isEmpty);
      if (isEmpty)
        return;
    }
  }

  PRInt32 offset = textAccessible->GetChildOffset(aEvent->mAccessible);

  nsAutoString text;
  aEvent->mAccessible->AppendTextTo(text, 0, PR_UINT32_MAX);
  if (text.IsEmpty())
    return;

  aEvent->mTextChangeEvent =
    new AccTextChangeEvent(textAccessible, offset, text, aEvent->IsShow(),
                           aEvent->mIsFromUserInput ? eFromUserInput : eNoUserInput);
}

////////////////////////////////////////////////////////////////////////////////
// NotificationController: content inserted notification

NotificationController::ContentInsertion::
  ContentInsertion(nsDocAccessible* aDocument, nsAccessible* aContainer,
                   nsIContent* aStartChildNode, nsIContent* aEndChildNode) :
  mDocument(aDocument), mContainer(aContainer)
{
  nsIContent* node = aStartChildNode;
  while (node != aEndChildNode) {
    mInsertedContent.AppendElement(node);
    node = node->GetNextSibling();
  }
}

NS_IMPL_CYCLE_COLLECTION_CLASS(NotificationController::ContentInsertion)

NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN_NATIVE(NotificationController::ContentInsertion)
  NS_IMPL_CYCLE_COLLECTION_UNLINK_NSCOMPTR(mContainer)
NS_IMPL_CYCLE_COLLECTION_UNLINK_END

NS_IMPL_CYCLE_COLLECTION_TRAVERSE_NATIVE_BEGIN(NotificationController::ContentInsertion)
  NS_CYCLE_COLLECTION_NOTE_EDGE_NAME(cb, "mContainer");
  cb.NoteXPCOMChild(static_cast<nsIAccessible*>(tmp->mContainer.get()));
NS_IMPL_CYCLE_COLLECTION_TRAVERSE_END

NS_IMPL_CYCLE_COLLECTION_ROOT_NATIVE(NotificationController::ContentInsertion,
                                     AddRef)
NS_IMPL_CYCLE_COLLECTION_UNROOT_NATIVE(NotificationController::ContentInsertion,
                                       Release)

void
NotificationController::ContentInsertion::Process()
{
#ifdef DEBUG_NOTIFICATIONS
  nsIContent* firstChildNode = mInsertedContent[0];

  nsCAutoString tag;
  firstChildNode->Tag()->ToUTF8String(tag);

  nsIAtom* atomid = firstChildNode->GetID();
  nsCAutoString id;
  if (atomid)
    atomid->ToUTF8String(id);

  nsCAutoString ctag;
  nsCAutoString cid;
  nsIAtom* catomid = nsnull;
  if (mContainer->IsContent()) {
    mContainer->GetContent()->Tag()->ToUTF8String(ctag);
    catomid = mContainer->GetContent()->GetID();
    if (catomid)
      catomid->ToUTF8String(cid);
  }

  printf("\npending content insertion process: %s@id='%s', container: %s@id='%s', inserted content amount: %d\n\n",
         tag.get(), id.get(), ctag.get(), cid.get(), mInsertedContent.Length());
#endif

  mDocument->ProcessContentInserted(mContainer, &mInsertedContent);

  mDocument = nsnull;
  mContainer = nsnull;
  mInsertedContent.Clear();
}