/*
Copyright (c) 2003-2012, CKSource - Frederico Knabben. All rights reserved.
For licensing, see LICENSE.html or http://ckeditor.com/license
*/

/**
 * @file Insert and remove numbered and bulleted lists.
 */

(function()
{
	var listNodeNames = { ol : 1, ul : 1 },
		emptyTextRegex = /^[\n\r\t ]*$/;

	var whitespaces = CKEDITOR.dom.walker.whitespaces(),
		bookmarks = CKEDITOR.dom.walker.bookmark(),
		nonEmpty = function( node ){ return !( whitespaces( node ) || bookmarks( node ) );},
		blockBogus = CKEDITOR.dom.walker.bogus();

	function cleanUpDirection( element )
	{
		var dir, parent, parentDir;
		if ( ( dir = element.getDirection() ) )
		{
			parent = element.getParent();
			while ( parent && !( parentDir = parent.getDirection() ) )
				parent = parent.getParent();

			if ( dir == parentDir )
				element.removeAttribute( 'dir' );
		}
	}

	// Inheirt inline styles from another element.
	function inheirtInlineStyles( parent, el )
	{
		var style = parent.getAttribute( 'style' );

		// Put parent styles before child styles.
		style && el.setAttribute( 'style',
			style.replace( /([^;])$/, '$1;' ) +
			( el.getAttribute( 'style' ) || '' ) );
	}

	CKEDITOR.plugins.list = {
		/*
		 * Convert a DOM list tree into a data structure that is easier to
		 * manipulate. This operation should be non-intrusive in the sense that it
		 * does not change the DOM tree, with the exception that it may add some
		 * markers to the list item nodes when database is specified.
		 */
		listToArray : function( listNode, database, baseArray, baseIndentLevel, grandparentNode )
		{
			if ( !listNodeNames[ listNode.getName() ] )
				return [];

			if ( !baseIndentLevel )
				baseIndentLevel = 0;
			if ( !baseArray )
				baseArray = [];

			// Iterate over all list items to and look for inner lists.
			for ( var i = 0, count = listNode.getChildCount() ; i < count ; i++ )
			{
				var listItem = listNode.getChild( i );

				// Fixing malformed nested lists by moving it into a previous list item. (#6236)
				if( listItem.type == CKEDITOR.NODE_ELEMENT && listItem.getName() in CKEDITOR.dtd.$list )
					CKEDITOR.plugins.list.listToArray( listItem, database, baseArray, baseIndentLevel + 1 );

				// It may be a text node or some funny stuff.
				if ( listItem.$.nodeName.toLowerCase() != 'li' )
					continue;

				var itemObj = { 'parent' : listNode, indent : baseIndentLevel, element : listItem, contents : [] };
				if ( !grandparentNode )
				{
					itemObj.grandparent = listNode.getParent();
					if ( itemObj.grandparent && itemObj.grandparent.$.nodeName.toLowerCase() == 'li' )
						itemObj.grandparent = itemObj.grandparent.getParent();
				}
				else
					itemObj.grandparent = grandparentNode;

				if ( database )
					CKEDITOR.dom.element.setMarker( database, listItem, 'listarray_index', baseArray.length );
				baseArray.push( itemObj );

				for ( var j = 0, itemChildCount = listItem.getChildCount(), child; j < itemChildCount ; j++ )
				{
					child = listItem.getChild( j );
					if ( child.type == CKEDITOR.NODE_ELEMENT && listNodeNames[ child.getName() ] )
						// Note the recursion here, it pushes inner list items with
						// +1 indentation in the correct order.
						CKEDITOR.plugins.list.listToArray( child, database, baseArray, baseIndentLevel + 1, itemObj.grandparent );
					else
						itemObj.contents.push( child );
				}
			}
			return baseArray;
		},

		// Convert our internal representation of a list back to a DOM forest.
		arrayToList : function( listArray, database, baseIndex, paragraphMode, dir )
		{
			if ( !baseIndex )
				baseIndex = 0;
			if ( !listArray || listArray.length < baseIndex + 1 )
				return null;
			var i,
				doc = listArray[ baseIndex ].parent.getDocument(),
				retval = new CKEDITOR.dom.documentFragment( doc ),
				rootNode = null,
				currentIndex = baseIndex,
				indentLevel = Math.max( listArray[ baseIndex ].indent, 0 ),
				currentListItem = null,
				orgDir,
				block,
				paragraphName = ( paragraphMode == CKEDITOR.ENTER_P ? 'p' : 'div' );
			while ( 1 )
			{
				var item = listArray[ currentIndex ],
					itemGrandParent = item.grandparent;

				orgDir = item.element.getDirection( 1 );

				if ( item.indent == indentLevel )
				{
					if ( !rootNode || listArray[ currentIndex ].parent.getName() != rootNode.getName() )
					{
						rootNode = listArray[ currentIndex ].parent.clone( false, 1 );
						dir && rootNode.setAttribute( 'dir', dir );
						retval.append( rootNode );
					}
					currentListItem = rootNode.append( item.element.clone( 0, 1 ) );

					if ( orgDir != rootNode.getDirection( 1 ) )
						currentListItem.setAttribute( 'dir', orgDir );

					for ( i = 0 ; i < item.contents.length ; i++ )
						currentListItem.append( item.contents[i].clone( 1, 1 ) );
					currentIndex++;
				}
				else if ( item.indent == Math.max( indentLevel, 0 ) + 1 )
				{
					// Maintain original direction (#6861).
					var currDir = listArray[ currentIndex - 1 ].element.getDirection( 1 ),
						listData = CKEDITOR.plugins.list.arrayToList( listArray, null, currentIndex, paragraphMode,
						currDir != orgDir ? orgDir: null );

					// If the next block is an <li> with another list tree as the first
					// child, we'll need to append a filler (<br>/NBSP) or the list item
					// wouldn't be editable. (#6724)
					if ( !currentListItem.getChildCount() && CKEDITOR.env.ie && !( doc.$.documentMode > 7 ))
						currentListItem.append( doc.createText( '\xa0' ) );
					currentListItem.append( listData.listNode );
					currentIndex = listData.nextIndex;
				}
				else if ( item.indent == -1 && !baseIndex && itemGrandParent )
				{
					if ( listNodeNames[ itemGrandParent.getName() ] )
					{
						currentListItem = item.element.clone( false, true );
						if ( orgDir != itemGrandParent.getDirection( 1 ) )
							currentListItem.setAttribute( 'dir', orgDir );
					}
					else
						currentListItem = new CKEDITOR.dom.documentFragment( doc );

					// Migrate all children to the new container,
					// apply the proper text direction.
					var dirLoose = itemGrandParent.getDirection( 1 ) != orgDir,
						li = item.element,
						className = li.getAttribute( 'class' ),
						style = li.getAttribute( 'style' );

					var needsBlock = currentListItem.type ==
					                 CKEDITOR.NODE_DOCUMENT_FRAGMENT &&
					                 ( paragraphMode != CKEDITOR.ENTER_BR || dirLoose ||
					                   style || className );

					var child, count = item.contents.length;
					for ( i = 0 ; i < count; i++ )
					{
						child = item.contents[ i ];

						if ( child.type == CKEDITOR.NODE_ELEMENT && child.isBlockBoundary() )
						{
							// Apply direction on content blocks.
							if ( dirLoose && !child.getDirection() )
								child.setAttribute( 'dir', orgDir );

							inheirtInlineStyles( li, child );

							className && child.addClass( className );
						}
						else if ( needsBlock )
						{
							// Establish new block to hold text direction and styles.
							if ( !block )
							{
								block = doc.createElement( paragraphName );
								dirLoose && block.setAttribute( 'dir', orgDir );
							}

							// Copy over styles to new block;
							style && block.setAttribute( 'style', style );
							className && block.setAttribute( 'class', className );

							block.append( child.clone( 1, 1 ) );
						}

						currentListItem.append( block || child.clone( 1, 1 ) );
					}

					if ( currentListItem.type == CKEDITOR.NODE_DOCUMENT_FRAGMENT
						 && currentIndex != listArray.length - 1 )
					{
						var last = currentListItem.getLast();
						if ( last && last.type == CKEDITOR.NODE_ELEMENT
								&& last.getAttribute( 'type' ) == '_moz' )
						{
							last.remove();
						}

						if ( !( last = currentListItem.getLast( nonEmpty )
							&& last.type == CKEDITOR.NODE_ELEMENT
							&& last.getName() in CKEDITOR.dtd.$block ) )
						{
							currentListItem.append( doc.createElement( 'br' ) );
						}
					}

					var currentListItemName = currentListItem.$.nodeName.toLowerCase();
					if ( !CKEDITOR.env.ie && ( currentListItemName == 'div' || currentListItemName == 'p' ) )
						currentListItem.appendBogus();
					retval.append( currentListItem );
					rootNode = null;
					currentIndex++;
				}
				else
					return null;

				block = null;

				if ( listArray.length <= currentIndex || Math.max( listArray[ currentIndex ].indent, 0 ) < indentLevel )
					break;
			}

			if ( database )
			{
				var currentNode = retval.getFirst(),
					listRoot = listArray[ 0 ].parent;

				while ( currentNode )
				{
					if ( currentNode.type == CKEDITOR.NODE_ELEMENT )
					{
						// Clear marker attributes for the new list tree made of cloned nodes, if any.
						CKEDITOR.dom.element.clearMarkers( database, currentNode );

						// Clear redundant direction attribute specified on list items.
						if ( currentNode.getName() in CKEDITOR.dtd.$listItem )
							cleanUpDirection( currentNode );
					}

					currentNode = currentNode.getNextSourceNode();
				}
			}

			return { listNode : retval, nextIndex : currentIndex };
		}
	};

	function onSelectionChange( evt )
	{
		if ( evt.editor.readOnly )
			return null;

		var path = evt.data.path,
			blockLimit = path.blockLimit,
			elements = path.elements,
			element,
			i;

		// Grouping should only happen under blockLimit.(#3940).
		for ( i = 0 ; i < elements.length && ( element = elements[ i ] )
			  && !element.equals( blockLimit ); i++ )
		{
			if ( listNodeNames[ elements[ i ].getName() ] )
				return this.setState( this.type == elements[ i ].getName() ? CKEDITOR.TRISTATE_ON : CKEDITOR.TRISTATE_OFF );
		}

		return this.setState( CKEDITOR.TRISTATE_OFF );
	}

	function changeListType( editor, groupObj, database, listsCreated )
	{
		// This case is easy...
		// 1. Convert the whole list into a one-dimensional array.
		// 2. Change the list type by modifying the array.
		// 3. Recreate the whole list by converting the array to a list.
		// 4. Replace the original list with the recreated list.
		var listArray = CKEDITOR.plugins.list.listToArray( groupObj.root, database ),
			selectedListItems = [];

		for ( var i = 0 ; i < groupObj.contents.length ; i++ )
		{
			var itemNode = groupObj.contents[i];
			itemNode = itemNode.getAscendant( 'li', true );
			if ( !itemNode || itemNode.getCustomData( 'list_item_processed' ) )
				continue;
			selectedListItems.push( itemNode );
			CKEDITOR.dom.element.setMarker( database, itemNode, 'list_item_processed', true );
		}

		var root = groupObj.root,
			doc = root.getDocument(),
			listNode,
			newListNode;

		for ( i = 0 ; i < selectedListItems.length ; i++ )
		{
			var listIndex = selectedListItems[i].getCustomData( 'listarray_index' );
			listNode = listArray[ listIndex ].parent;

			// Switch to new list node for this particular item.
			if ( !listNode.is( this.type ) )
			{
				newListNode = doc.createElement( this.type );
				// Copy all attributes, except from 'start' and 'type'.
				listNode.copyAttributes( newListNode, { start : 1, type : 1 } );
				// The list-style-type property should be ignored.
				newListNode.removeStyle( 'list-style-type' );
				listArray[ listIndex ].parent = newListNode;
			}
		}

		var newList = CKEDITOR.plugins.list.arrayToList( listArray, database, null, editor.config.enterMode );
		var child, length = newList.listNode.getChildCount();
		for ( i = 0 ; i < length && ( child = newList.listNode.getChild( i ) ) ; i++ )
		{
			if ( child.getName() == this.type )
				listsCreated.push( child );
		}
		newList.listNode.replace( groupObj.root );
	}

	var headerTagRegex = /^h[1-6]$/;

	function createList( editor, groupObj, listsCreated )
	{
		var contents = groupObj.contents,
			doc = groupObj.root.getDocument(),
			listContents = [];

		// It is possible to have the contents returned by DomRangeIterator to be the same as the root.
		// e.g. when we're running into table cells.
		// In such a case, enclose the childNodes of contents[0] into a <div>.
		if ( contents.length == 1 && contents[0].equals( groupObj.root ) )
		{
			var divBlock = doc.createElement( 'div' );
			contents[0].moveChildren && contents[0].moveChildren( divBlock );
			contents[0].append( divBlock );
			contents[0] = divBlock;
		}

		// Calculate the common parent node of all content blocks.
		var commonParent = groupObj.contents[0].getParent();
		for ( var i = 0 ; i < contents.length ; i++ )
			commonParent = commonParent.getCommonAncestor( contents[i].getParent() );

		var useComputedState = editor.config.useComputedState,
			listDir, explicitDirection;

		useComputedState = useComputedState === undefined || useComputedState;

		// We want to insert things that are in the same tree level only, so calculate the contents again
		// by expanding the selected blocks to the same tree level.
		for ( i = 0 ; i < contents.length ; i++ )
		{
			var contentNode = contents[i],
				parentNode;
			while ( ( parentNode = contentNode.getParent() ) )
			{
				if ( parentNode.equals( commonParent ) )
				{
					listContents.push( contentNode );

					// Determine the lists's direction.
					if ( !explicitDirection && contentNode.getDirection() )
						explicitDirection = 1;

					var itemDir = contentNode.getDirection( useComputedState );

					if ( listDir !== null )
					{
						// If at least one LI have a different direction than current listDir, we can't have listDir.
						if ( listDir && listDir != itemDir )
							listDir = null;
						else
							listDir = itemDir;
					}

					break;
				}
				contentNode = parentNode;
			}
		}

		if ( listContents.length < 1 )
			return;

		// Insert the list to the DOM tree.
		var insertAnchor = listContents[ listContents.length - 1 ].getNext(),
			listNode = doc.createElement( this.type );

		listsCreated.push( listNode );

		var contentBlock, listItem;

		while ( listContents.length )
		{
			contentBlock = listContents.shift();
			listItem = doc.createElement( 'li' );

			// Preserve preformat block and heading structure when converting to list item. (#5335) (#5271)
			if ( contentBlock.is( 'pre' ) || headerTagRegex.test( contentBlock.getName() ) )
				contentBlock.appendTo( listItem );
			else
			{
				contentBlock.copyAttributes( listItem );
				// Remove direction attribute after it was merged into list root. (#7657)
				if ( listDir && contentBlock.getDirection() )
				{
					listItem.removeStyle( 'direction' );
					listItem.removeAttribute( 'dir' );
				}
				contentBlock.moveChildren( listItem );
				contentBlock.remove();
			}

			listItem.appendTo( listNode );
		}

		// Apply list root dir only if it has been explicitly declared.
		if ( listDir && explicitDirection )
			listNode.setAttribute( 'dir', listDir );

		if ( insertAnchor )
			listNode.insertBefore( insertAnchor );
		else
			listNode.appendTo( commonParent );
	}

	function removeList( editor, groupObj, database )
	{
		// This is very much like the change list type operation.
		// Except that we're changing the selected items' indent to -1 in the list array.
		var listArray = CKEDITOR.plugins.list.listToArray( groupObj.root, database ),
			selectedListItems = [];

		for ( var i = 0 ; i < groupObj.contents.length ; i++ )
		{
			var itemNode = groupObj.contents[i];
			itemNode = itemNode.getAscendant( 'li', true );
			if ( !itemNode || itemNode.getCustomData( 'list_item_processed' ) )
				continue;
			selectedListItems.push( itemNode );
			CKEDITOR.dom.element.setMarker( database, itemNode, 'list_item_processed', true );
		}

		var lastListIndex = null;
		for ( i = 0 ; i < selectedListItems.length ; i++ )
		{
			var listIndex = selectedListItems[i].getCustomData( 'listarray_index' );
			listArray[listIndex].indent = -1;
			lastListIndex = listIndex;
		}

		// After cutting parts of the list out with indent=-1, we still have to maintain the array list
		// model's nextItem.indent <= currentItem.indent + 1 invariant. Otherwise the array model of the
		// list cannot be converted back to a real DOM list.
		for ( i = lastListIndex + 1 ; i < listArray.length ; i++ )
		{
			if ( listArray[i].indent > listArray[i-1].indent + 1 )
			{
				var indentOffset = listArray[i-1].indent + 1 - listArray[i].indent;
				var oldIndent = listArray[i].indent;
				while ( listArray[i] && listArray[i].indent >= oldIndent )
				{
					listArray[i].indent += indentOffset;
					i++;
				}
				i--;
			}
		}

		var newList = CKEDITOR.plugins.list.arrayToList( listArray, database, null, editor.config.enterMode,
			groupObj.root.getAttribute( 'dir' ) );

		// Compensate <br> before/after the list node if the surrounds are non-blocks.(#3836)
		var docFragment = newList.listNode, boundaryNode, siblingNode;
		function compensateBrs( isStart )
		{
			if ( ( boundaryNode = docFragment[ isStart ? 'getFirst' : 'getLast' ]() )
				 && !( boundaryNode.is && boundaryNode.isBlockBoundary() )
				 && ( siblingNode = groupObj.root[ isStart ? 'getPrevious' : 'getNext' ]
				      ( CKEDITOR.dom.walker.whitespaces( true ) ) )
				 && !( siblingNode.is && siblingNode.isBlockBoundary( { br : 1 } ) ) )
				editor.document.createElement( 'br' )[ isStart ? 'insertBefore' : 'insertAfter' ]( boundaryNode );
		}
		compensateBrs( true );
		compensateBrs();

		docFragment.replace( groupObj.root );
	}

	function listCommand( name, type )
	{
		this.name = name;
		this.type = type;
	}

	var elementType = CKEDITOR.dom.walker.nodeType( CKEDITOR.NODE_ELEMENT );

	// Merge child nodes with direction preserved. (#7448)
	function mergeChildren( from, into, refNode, forward )
	{
		var child, itemDir;
		while ( ( child = from[ forward ? 'getLast' : 'getFirst' ]( elementType ) ) )
		{
			if ( ( itemDir = child.getDirection( 1 ) ) !== into.getDirection( 1 ) )
				child.setAttribute( 'dir', itemDir );

			child.remove();

			refNode ?
				child[ forward ? 'insertBefore' : 'insertAfter' ]( refNode ) :
				into.append( child, forward  );
		}
	}

	listCommand.prototype = {
		exec : function( editor )
		{
			var doc = editor.document,
				config = editor.config,
				selection = editor.getSelection(),
				ranges = selection && selection.getRanges( true );

			// There should be at least one selected range.
			if ( !ranges || ranges.length < 1 )
				return;

			// Midas lists rule #1 says we can create a list even in an empty document.
			// But DOM iterator wouldn't run if the document is really empty.
			// So create a paragraph if the document is empty and we're going to create a list.
			if ( this.state == CKEDITOR.TRISTATE_OFF )
			{
				var body = doc.getBody();
				if ( !body.getFirst( nonEmpty ) )
				{
					config.enterMode == CKEDITOR.ENTER_BR ?
						body.appendBogus() :
						ranges[ 0 ].fixBlock( 1, config.enterMode == CKEDITOR.ENTER_P ? 'p' : 'div' );

					selection.selectRanges( ranges );
				}
				// Maybe a single range there enclosing the whole list,
				// turn on the list state manually(#4129).
				else
				{
					var range = ranges.length == 1 && ranges[ 0 ],
						enclosedNode = range && range.getEnclosedNode();
					if ( enclosedNode && enclosedNode.is
						&& this.type == enclosedNode.getName() )
							this.setState( CKEDITOR.TRISTATE_ON );
				}
			}

			var bookmarks = selection.createBookmarks( true );

			// Group the blocks up because there are many cases where multiple lists have to be created,
			// or multiple lists have to be cancelled.
			var listGroups = [],
				database = {},
				rangeIterator = ranges.createIterator(),
				index = 0;

			while ( ( range = rangeIterator.getNextRange() ) && ++index )
			{
				var boundaryNodes = range.getBoundaryNodes(),
					startNode = boundaryNodes.startNode,
					endNode = boundaryNodes.endNode;

				if ( startNode.type == CKEDITOR.NODE_ELEMENT && startNode.getName() == 'td' )
					range.setStartAt( boundaryNodes.startNode, CKEDITOR.POSITION_AFTER_START );

				if ( endNode.type == CKEDITOR.NODE_ELEMENT && endNode.getName() == 'td' )
					range.setEndAt( boundaryNodes.endNode, CKEDITOR.POSITION_BEFORE_END );

				var iterator = range.createIterator(),
					block;

				iterator.forceBrBreak = ( this.state == CKEDITOR.TRISTATE_OFF );

				while ( ( block = iterator.getNextParagraph() ) )
				{
					// Avoid duplicate blocks get processed across ranges.
					if( block.getCustomData( 'list_block' ) )
						continue;
					else
						CKEDITOR.dom.element.setMarker( database, block, 'list_block', 1 );

					var path = new CKEDITOR.dom.elementPath( block ),
						pathElements = path.elements,
						pathElementsCount = pathElements.length,
						listNode = null,
						processedFlag = 0,
						blockLimit = path.blockLimit,
						element;

					// First, try to group by a list ancestor.
					for ( var i = pathElementsCount - 1; i >= 0 && ( element = pathElements[ i ] ); i-- )
					{
						if ( listNodeNames[ element.getName() ]
							 && blockLimit.contains( element ) )     // Don't leak outside block limit (#3940).
						{
							// If we've encountered a list inside a block limit
							// The last group object of the block limit element should
							// no longer be valid. Since paragraphs after the list
							// should belong to a different group of paragraphs before
							// the list. (Bug #1309)
							blockLimit.removeCustomData( 'list_group_object_' + index );

							var groupObj = element.getCustomData( 'list_group_object' );
							if ( groupObj )
								groupObj.contents.push( block );
							else
							{
								groupObj = { root : element, contents : [ block ] };
								listGroups.push( groupObj );
								CKEDITOR.dom.element.setMarker( database, element, 'list_group_object', groupObj );
							}
							processedFlag = 1;
							break;
						}
					}

					if ( processedFlag )
						continue;

					// No list ancestor? Group by block limit, but don't mix contents from different ranges.
					var root = blockLimit;
					if ( root.getCustomData( 'list_group_object_' + index ) )
						root.getCustomData( 'list_group_object_' + index ).contents.push( block );
					else
					{
						groupObj = { root : root, contents : [ block ] };
						CKEDITOR.dom.element.setMarker( database, root, 'list_group_object_' + index, groupObj );
						listGroups.push( groupObj );
					}
				}
			}

			// Now we have two kinds of list groups, groups rooted at a list, and groups rooted at a block limit element.
			// We either have to build lists or remove lists, for removing a list does not makes sense when we are looking
			// at the group that's not rooted at lists. So we have three cases to handle.
			var listsCreated = [];
			while ( listGroups.length > 0 )
			{
				groupObj = listGroups.shift();
				if ( this.state == CKEDITOR.TRISTATE_OFF )
				{
					if ( listNodeNames[ groupObj.root.getName() ] )
						changeListType.call( this, editor, groupObj, database, listsCreated );
					else
						createList.call( this, editor, groupObj, listsCreated );
				}
				else if ( this.state == CKEDITOR.TRISTATE_ON && listNodeNames[ groupObj.root.getName() ] )
					removeList.call( this, editor, groupObj, database );
			}

			// For all new lists created, merge into adjacent, same type lists.
			for ( i = 0 ; i < listsCreated.length ; i++ )
				mergeListSiblings( listsCreated[ i ] );

			// Clean up, restore selection and update toolbar button states.
			CKEDITOR.dom.element.clearAllMarkers( database );
			selection.selectBookmarks( bookmarks );
			editor.focus();
		}
	};

	// Merge list adjacent, of same type lists.
	function mergeListSiblings( listNode )
	{
		var mergeSibling;
		( mergeSibling = function( rtl )
		{
			var sibling = listNode[ rtl ? 'getPrevious' : 'getNext' ]( nonEmpty );
			if ( sibling && sibling.type == CKEDITOR.NODE_ELEMENT &&
			     sibling.is( listNode.getName() ) )
			{
				// Move children order by merge direction.(#3820)
				mergeChildren( listNode, sibling, null, !rtl );

				listNode.remove();
				listNode = sibling;
			}
		} )();
		mergeSibling( 1 );
	}

	var dtd = CKEDITOR.dtd;
	var tailNbspRegex = /[\t\r\n ]*(?:&nbsp;|\xa0)$/;

	function indexOfFirstChildElement( element, tagNameList )
	{
		var child,
			children = element.children,
			length = children.length;

		for ( var i = 0 ; i < length ; i++ )
		{
			child = children[ i ];
			if ( child.name && ( child.name in tagNameList ) )
				return i;
		}

		return length;
	}

	function getExtendNestedListFilter( isHtmlFilter )
	{
		// An element filter function that corrects nested list start in an empty
		// list item for better displaying/outputting. (#3165)
		return function( listItem )
		{
			var children = listItem.children,
				firstNestedListIndex = indexOfFirstChildElement( listItem, dtd.$list ),
				firstNestedList = children[ firstNestedListIndex ],
				nodeBefore = firstNestedList && firstNestedList.previous,
				tailNbspmatch;

			if ( nodeBefore
				&& ( nodeBefore.name && nodeBefore.name == 'br'
					|| nodeBefore.value && ( tailNbspmatch = nodeBefore.value.match( tailNbspRegex ) ) ) )
			{
				var fillerNode = nodeBefore;

				// Always use 'nbsp' as filler node if we found a nested list appear
				// in front of a list item.
				if ( !( tailNbspmatch && tailNbspmatch.index ) && fillerNode == children[ 0 ] )
					children[ 0 ] = ( isHtmlFilter || CKEDITOR.env.ie ) ?
					                 new CKEDITOR.htmlParser.text( '\xa0' ) :
									 new CKEDITOR.htmlParser.element( 'br', {} );

				// Otherwise the filler is not needed anymore.
				else if ( fillerNode.name == 'br' )
					children.splice( firstNestedListIndex - 1, 1 );
				else
					fillerNode.value = fillerNode.value.replace( tailNbspRegex, '' );
			}

		};
	}

	var defaultListDataFilterRules = { elements : {} };
	for ( var i in dtd.$listItem )
		defaultListDataFilterRules.elements[ i ] = getExtendNestedListFilter();

	var defaultListHtmlFilterRules = { elements : {} };
	for ( i in dtd.$listItem )
		defaultListHtmlFilterRules.elements[ i ] = getExtendNestedListFilter( true );

	// Check if node is block element that recieves text.
	function isTextBlock( node )
	{
		return node.type == CKEDITOR.NODE_ELEMENT &&
			   ( node.getName() in CKEDITOR.dtd.$block ||
				 node.getName() in CKEDITOR.dtd.$listItem ) &&
			   CKEDITOR.dtd[ node.getName() ][ '#' ];
	}

	// Merge the visual line content at the cursor range into the block.
	function joinNextLineToCursor( editor, cursor, nextCursor )
	{
		editor.fire( 'saveSnapshot' );

		// Merge with previous block's content.
		nextCursor.enlarge( CKEDITOR.ENLARGE_LIST_ITEM_CONTENTS );
		var frag = nextCursor.extractContents();

		cursor.trim( false, true );
		var bm = cursor.createBookmark();

		// Kill original bogus;
		var currentPath = new CKEDITOR.dom.elementPath( cursor.startContainer );
		var currentLi = currentPath.lastElement.getAscendant( 'li', 1 );

		var bogus = currentPath.block.getBogus();
		bogus && bogus.remove();

		// Kill the tail br in extracted.
		var last = frag.getLast();
		if ( last && last.type == CKEDITOR.NODE_ELEMENT && last.is( 'br' ) )
			last.remove();

		// Insert fragment at the range position.
		var nextNode = cursor.startContainer.getChild( cursor.startOffset );
		if ( nextNode )
			frag.insertBefore( nextNode );
		else
			cursor.startContainer.append( frag );

		var nextPath = new CKEDITOR.dom.elementPath( nextCursor.startContainer );
		var nextLi = nextCursor.startContainer.getAscendant( 'li', 1 );

		// Move the sub list nested in the next list item.
		if ( nextLi )
		{
			var sublist = getSubList( nextLi );
			if ( sublist )
			{
				// If next line is in the sub list of the current list item.
				if ( currentLi.contains( nextLi ) )
				{
					mergeChildren( sublist, nextLi.getParent(), nextLi );
					sublist.remove();
				}
				// Migrate the sub list to current list item.
				else
					currentLi.append( sublist );
			}
		}

		// Remove any remaining empty path blocks at next line after merging.
		while ( nextCursor.checkStartOfBlock() &&
			 nextCursor.checkEndOfBlock() )
		{
			nextPath = new CKEDITOR.dom.elementPath( nextCursor.startContainer );
			var nextBlock = nextPath.block, parent;

			// Check if also to remove empty list.
			if ( nextBlock.is( 'li' ) )
			{
				parent = nextBlock.getParent();
				if ( nextBlock.equals( parent.getLast( nonEmpty ) )
						&& nextBlock.equals( parent.getFirst( nonEmpty ) ) )
					nextBlock = parent;
			}

			nextCursor.moveToPosition( nextBlock, CKEDITOR.POSITION_BEFORE_START );
			nextBlock.remove();
		}

		// Check if need to further merge with the list resides after the merged block. (#9080)
		var walkerRng = nextCursor.clone(), body = editor.document.getBody();
		walkerRng.setEndAt( body, CKEDITOR.POSITION_BEFORE_END );
		var walker = new CKEDITOR.dom.walker( walkerRng );
		walker.evaluator = function( node ) { return nonEmpty( node ) && !blockBogus( node ); };
		var next = walker.next();
		if ( next && next.type == CKEDITOR.NODE_ELEMENT && next.getName() in CKEDITOR.dtd.$list )
			mergeListSiblings( next );

		cursor.moveToBookmark( bm );

		// Make fresh selection.
		cursor.select();

		editor.selectionChange( 1 );
		editor.fire( 'saveSnapshot' );
	}

	function getSubList( li )
	{
		var last = li.getLast( nonEmpty );
		return last && last.type == CKEDITOR.NODE_ELEMENT && last.getName() in listNodeNames ? last : null;
	}

	CKEDITOR.plugins.add( 'list',
	{
		init : function( editor )
		{
			// Register commands.
			var numberedListCommand = editor.addCommand( 'numberedlist', new listCommand( 'numberedlist', 'ol' ) ),
				bulletedListCommand = editor.addCommand( 'bulletedlist', new listCommand( 'bulletedlist', 'ul' ) );

			// Register the toolbar button.
			editor.ui.addButton( 'NumberedList',
				{
					label : editor.lang.numberedlist,
					command : 'numberedlist'
				} );
			editor.ui.addButton( 'BulletedList',
				{
					label : editor.lang.bulletedlist,
					command : 'bulletedlist'
				} );

			// Register the state changing handlers.
			editor.on( 'selectionChange', CKEDITOR.tools.bind( onSelectionChange, numberedListCommand ) );
			editor.on( 'selectionChange', CKEDITOR.tools.bind( onSelectionChange, bulletedListCommand ) );

				// Handled backspace/del key to join list items. (#8248,#9080)
				editor.on( 'key', function( evt )
				{
					var key = evt.data.keyCode;

					// DEl/BACKSPACE
					if ( editor.mode == 'wysiwyg' && key in { 8 : 1, 46 : 1 } )
					{
						var sel = editor.getSelection(),
						range = sel.getRanges()[ 0 ];

						if ( !range.collapsed )
							return;

						var isBackspace = key == 8;
						var body = editor.document.getBody();
						var walker = new CKEDITOR.dom.walker( range.clone() );
						walker.evaluator = function( node ) { return nonEmpty( node ) && !blockBogus( node ); };

						var cursor = range.clone();

						if ( isBackspace )
						{
							var previous, joinWith;

							var path = new CKEDITOR.dom.elementPath( range.startContainer );

							// Join a sub list's first line, with the previous visual line in parent.
							if ( ( previous = path.contains( listNodeNames ) ) &&
							     range.checkBoundaryOfElement( previous, CKEDITOR.START ) &&
							     ( previous = previous.getParent() ) && previous.is( 'li' ) &&
							     ( previous = getSubList( previous ) ) )
							{
								joinWith = previous;
								previous = previous.getPrevious( nonEmpty );
								// Place cursor before the nested list.
								cursor.moveToPosition(
									previous && blockBogus( previous ) ? previous : joinWith,
									CKEDITOR.POSITION_BEFORE_START );
							}
							// Join any line following a list, with the last visual line of the list.
							else
							{
								walker.range.setStartAt( body, CKEDITOR.POSITION_AFTER_START );
								walker.range.setEnd( range.startContainer, range.startOffset );
								previous = walker.previous();

								if ( previous && previous.type == CKEDITOR.NODE_ELEMENT &&
								   ( previous.getName() in listNodeNames || previous.is( 'li' ) ) )
								{
									if ( !previous.is( 'li' ) )
									{
										walker.range.selectNodeContents( previous );
										walker.reset();
										walker.evaluator = isTextBlock;
										previous = walker.previous();
									}

									joinWith = previous;
									// Place cursor at the end of previous block.
									cursor.moveToElementEditEnd( joinWith );
								}
							}

							if ( joinWith )
							{
								joinNextLineToCursor( editor, cursor, range );
								evt.cancel();
							}
						}
						else
						{
							var li = range.startContainer.getAscendant( 'li', 1 );
							if ( li )
							{
								walker.range.setEndAt( body, CKEDITOR.POSITION_BEFORE_END );

								var last = li.getLast( nonEmpty );
								var block = last && isTextBlock( last ) ? last : li;

								// Indicate cursor at the visual end of an list item.
								var isAtEnd = 0;

								var next = walker.next();

								// When list item contains a sub list.
								if ( next && next.type == CKEDITOR.NODE_ELEMENT &&
									 next.getName() in listNodeNames
									 && next.equals( last ) )
								{
									isAtEnd = 1;

									// Move to the first item in sub list.
									next = walker.next();
								}
								// Right at the end of list item.
								else if ( range.checkBoundaryOfElement( block, CKEDITOR.END ) )
									isAtEnd = 1;


								if ( isAtEnd && next )
								{
									// Put cursor range there.
									var nextLine = range.clone();
									nextLine.moveToElementEditStart( next );

									joinNextLineToCursor( editor, cursor, nextLine );
									evt.cancel();
								}
							}
						}

						// The backspace/del could potentially put cursor at a bad position,
						// being it handled or not, check immediately the selection to have it fixed.
						setTimeout( function() { editor.selectionChange( 1 ); } );
					}
				} );
		},

		afterInit : function ( editor )
		{
			var dataProcessor = editor.dataProcessor;
			if ( dataProcessor )
			{
				dataProcessor.dataFilter.addRules( defaultListDataFilterRules );
				dataProcessor.htmlFilter.addRules( defaultListHtmlFilterRules );
			}
		},

		requires : [ 'domiterator' ]
	} );
})();