///import editor.js
///import core/browser.js
///import core/dom/dom.js
///import core/dom/dtd.js
///import core/dom/domUtils.js
///import core/dom/Range.js
/**
 * @class baidu.editor.dom.Selection    Selection类
 */
(function () {

    function getBoundaryInformation( range, start ) {

        var getIndex = domUtils.getNodeIndex;

        range = range.duplicate();
        range.collapse( start );


        var parent = range.parentElement();

        //如果节点里没有子节点，直接退出
        if ( !parent.hasChildNodes() ) {
            return  {container:parent,offset:0};
        }

        var siblings = parent.children,
            child,
            testRange = range.duplicate(),
            startIndex = 0,endIndex = siblings.length - 1,index = -1,
            distance;

        while ( startIndex <= endIndex ) {
            index = Math.floor( (startIndex + endIndex) / 2 );
            child = siblings[index];
            testRange.moveToElementText( child );
            var position = testRange.compareEndPoints( 'StartToStart', range );


            if ( position > 0 ) {

                endIndex = index - 1;
            } else if ( position < 0 ) {

                startIndex = index + 1;
            } else {
                //trace:1043
                return  {container:parent,offset:getIndex( child )};
            }
        }

        if ( index == -1 ) {
            testRange.moveToElementText( parent );
            testRange.setEndPoint( 'StartToStart', range );
            distance = testRange.text.replace( /(\r\n|\r)/g, '\n' ).length;
            siblings = parent.childNodes;
            if ( !distance ) {
                child = siblings[siblings.length - 1];
                return  {container:child,offset:child.nodeValue.length};
            }

            var i = siblings.length;
            while ( distance > 0 )
                distance -= siblings[ --i ].nodeValue.length;

            return {container:siblings[i],offset:-distance}
        }

        testRange.collapse( position > 0 );
        testRange.setEndPoint( position > 0 ? 'StartToStart' : 'EndToStart', range );
        distance = testRange.text.replace( /(\r\n|\r)/g, '\n' ).length;
        if ( !distance ) {
            return  dtd.$empty[child.tagName] || dtd.$nonChild[child.tagName]?

            {container : parent,offset:getIndex( child ) + (position > 0 ? 0 : 1)} :
            {container : child,offset: position > 0 ? 0 : child.childNodes.length}
        }

        while ( distance > 0 ) {
            try{
                var pre = child;
                child = child[position > 0 ? 'previousSibling' : 'nextSibling'];
                distance -= child.nodeValue.length;
            }catch(e){
                return {container:parent,offset:getIndex(pre)};
            }

        }
        return  {container:child,offset:position > 0 ? -distance : child.nodeValue.length + distance}
    }

    /**
     * 将ieRange转换为Range对象
     * @param {Range}   ieRange    ieRange对象
     * @param {Range}   range      Range对象
     * @return  {Range}  range       返回转换后的Range对象
     */
    function transformIERangeToRange( ieRange, range ) {
        if ( ieRange.item ) {
            range.selectNode( ieRange.item( 0 ) );
        } else {
            var bi = getBoundaryInformation( ieRange, true );
            range.setStart( bi.container, bi.offset );
            if ( ieRange.compareEndPoints( 'StartToEnd',ieRange ) != 0 ) {
                bi = getBoundaryInformation( ieRange, false );
                range.setEnd( bi.container, bi.offset );
            }
        }
        return range;
    }

    /**
     * 获得ieRange
     * @param {Selection} sel    Selection对象
     * @return {ieRange}    得到ieRange
     */
    function _getIERange(sel){
        var ieRange;
        //ie下有可能报错
        try{
            ieRange = sel.getNative().createRange();
        }catch(e){
            return null;
        }
        var el = ieRange.item ? ieRange.item( 0 ) : ieRange.parentElement();
        if ( ( el.ownerDocument || el ) === sel.document ) {
            return ieRange;
        }
        return null;
    }
    var Selection = dom.Selection = function ( doc ) {
        var me = this, iframe;
        me.document = doc;

        if ( ie ) {
            iframe = domUtils.getWindow(doc).frameElement;
            domUtils.on( iframe, 'beforedeactivate', function () {
                me._bakIERange = me.getIERange();
            } );
            domUtils.on( iframe, 'activate', function () {
                try {
                    if ( !_getIERange(me) && me._bakIERange ) {
                        me._bakIERange.select();
                    }
                } catch ( ex ) {
                }
                me._bakIERange = null;
            } );
        }
        iframe = doc = null;
    };

    Selection.prototype = {
        /**
         * 获取原生seleciton对象
         * @public
         * @function
         * @name    baidu.editor.dom.Selection.getNative
         * @return {Selection}    获得selection对象
         */
        getNative : function () {
            var doc = this.document;
            try{
                return !doc ? null : ie ? doc.selection : domUtils.getWindow( doc ).getSelection();
            }catch(e){
                return null;
            }
        },



        /**
         * 获得ieRange
         * @public
         * @function
         * @name    baidu.editor.dom.Selection.getIERange
         * @return {ieRange}    返回ie原生的Range
         */
        getIERange : function () {

            var ieRange = _getIERange(this);
            if ( !ieRange ) {
                if ( this._bakIERange ) {
                    return this._bakIERange;
                }
            }
            return ieRange;
        },

        /**
         * 缓存当前选区的range和选区的开始节点
         * @public
         * @function
         * @name    baidu.editor.dom.Selection.cache
         */
        cache : function () {
            this.clear();
            this._cachedRange = this.getRange();
            this._cachedStartElement = this.getStart();

            this._cachedStartElementPath = this.getStartElementPath();
        },

        getStartElementPath : function(){
            if(this._cachedStartElementPath){
                return this._cachedStartElementPath;
            }
            var start = this.getStart();
            if(start){
                return domUtils.findParents(start,true,null,true)
            }
            return [];
        },
        /**
         * 清空缓存
         * @public
         * @function
         * @name    baidu.editor.dom.Selection.clear
         */
        clear : function () {
            this._cachedStartElementPath = this._cachedRange = this._cachedStartElement = null;
        },
        /**
         * 编辑器是否得到了选区
         */
        isFocus : function(){
            try{
                return browser.ie  && _getIERange(this) || !browser.ie &&  this.getNative().rangeCount ? true : false;
            }catch(e){
                return false;
            }

        },
        /**
         * 获取选区对应的Range
         * @public
         * @function
         * @name    baidu.editor.dom.Selection.getRange
         * @returns {baidu.editor.dom.Range}    得到Range对象
         */
        getRange : function () {
            var me = this;
            
            function optimze(range){
                var child = me.document.body.firstChild,
                    collapsed = range.collapsed;
                while(child && child.firstChild){
                    range.setStart(child,0);
                    child = child.firstChild;
                }
                if(!range.startContainer){
                    range.setStart(me.document.body,0)
                }
                if(collapsed){
                    range.collapse(true);
                }
            }
            if ( me._cachedRange != null ) {
                return this._cachedRange;
            }
            var range = new baidu.editor.dom.Range( me.document );

            if ( ie ) {
                var nativeRange = me.getIERange();
                if(nativeRange){
                    transformIERangeToRange( nativeRange, range );
                }else{
                    optimze(range)
                }

            } else {
                var sel = me.getNative();
                if ( sel && sel.rangeCount ) {
                    var firstRange = sel.getRangeAt( 0 ) ;
                    var lastRange = sel.getRangeAt( sel.rangeCount - 1 );
                    range.setStart( firstRange.startContainer, firstRange.startOffset ).setEnd( lastRange.endContainer, lastRange.endOffset );
                    if(range.collapsed && domUtils.isBody(range.startContainer) && !range.startOffset){
                        optimze(range)
                    }
                } else {
                    //trace:1734 有可能已经不在dom树上了，标识的节点
                    if(this._bakRange && domUtils.inDoc(this._bakRange.startContainer,this.document))
                        return this._bakRange;
                    optimze(range)
                        
                }
                
            }

            return this._bakRange = range;
        },

        /**
         * 获取开始元素，用于状态反射
         * @public
         * @function
         * @name    baidu.editor.dom.Selection.getStart
         * @return {Element}     获得开始元素
         */
        getStart : function () {
            if ( this._cachedStartElement ) {
                return this._cachedStartElement;
            }
            var range = ie ? this.getIERange()  : this.getRange(),
                tmpRange,
                start,tmp,parent;

            if (ie) {
                if(!range){
                    //todo 给第一个值可能会有问题
                   return this.document.body.firstChild;
                }
                //control元素
                if (range.item)
                    return range.item(0);

                tmpRange = range.duplicate();
                //修正ie下<b>x</b>[xx] 闭合后 <b>x|</b>xx
                tmpRange.text.length > 0 && tmpRange.moveStart('character',1);
                tmpRange.collapse(1);
                start = tmpRange.parentElement();


                parent = tmp = range.parentElement();
                while (tmp = tmp.parentNode) {
                    if (tmp == start) {
                        start = parent;
                        break;
                    }
                }

            } else {
                range.shrinkBoundary();
                start = range.startContainer;

                if (start.nodeType == 1 && start.hasChildNodes())
                    start = start.childNodes[Math.min(start.childNodes.length - 1, range.startOffset)];

                if (start.nodeType == 3)
                    return start.parentNode;


            }
            return start;

        },
        /**
         * 得到选区中的文本
         * @public
         * @function
         * @name    baidu.editor.dom.Selection.getText
         * @return  {String}    选区中包含的文本
         */
        getText : function(){
            var nativeSel,nativeRange;
            if(this.isFocus() && (nativeSel = this.getNative())){
                nativeRange = browser.ie ? nativeSel.createRange() : nativeSel.getRangeAt(0);
                return browser.ie ? nativeRange.text : nativeRange.toString();
            }
            return '';
        }
    };


})();