/**
 * 选集
 * @file
 * @module UE.dom
 * @class Selection
 * @since 1.2.6.1
 */

/**
 * 选区集合
 * @unfile
 * @module UE.dom
 * @class Selection
 */
(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 ( browser.ie9below ) {
            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 = {

        rangeInBody : function(rng,txtRange){
            var node = browser.ie9below || txtRange ? rng.item ? rng.item() : rng.parentElement() : rng.startContainer;

            return node === this.document.body || domUtils.inDoc(node,this.document);
        },

        /**
         * 获取原生seleciton对象
         * @method getNative
         * @return { Object } 获得selection对象
         * @example
         * ```javascript
         * editor.selection.getNative();
         * ```
         */
        getNative:function () {
            var doc = this.document;
            try {
                return !doc ? null : browser.ie9below ? doc.selection : domUtils.getWindow( doc ).getSelection();
            } catch ( e ) {
                return null;
            }
        },

        /**
         * 获得ieRange
         * @method getIERange
         * @return { Object } 返回ie原生的Range
         * @example
         * ```javascript
         * editor.selection.getIERange();
         * ```
         */
        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
         * @method cache
         */
        cache:function () {
            this.clear();
            this._cachedRange = this.getRange();
            this._cachedStartElement = this.getStart();
            this._cachedStartElementPath = this.getStartElementPath();
        },

        /**
         * 获取选区开始位置的父节点到body
         * @method getStartElementPath
         * @return { Array } 返回父节点集合
         * @example
         * ```javascript
         * editor.selection.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
         * @method clear
         */
        clear:function () {
            this._cachedStartElementPath = this._cachedRange = this._cachedStartElement = null;
        },

        /**
         * 编辑器是否得到了选区
         * @method isFocus
         */
        isFocus:function () {
            try {
                if(browser.ie9below){

                    var nativeRange = _getIERange(this);
                    return !!(nativeRange && this.rangeInBody(nativeRange));
                }else{
                    return !!this.getNative().rangeCount;
                }
            } catch ( e ) {
                return false;
            }

        },

        /**
         * 获取选区对应的Range
         * @method getRange
         * @return { Object } 得到Range对象
         * @example
         * ```javascript
         * editor.selection.getRange();
         * ```
         */
        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 ( browser.ie9below ) {
                var nativeRange = me.getIERange();
                if ( nativeRange ) {
                    //备份的_bakIERange可能已经实效了，dom树发生了变化比如从源码模式切回来，所以try一下，实效就放到body开始位置
                    try{
                        transformIERangeToRange( nativeRange, range );
                    }catch(e){
                        optimze( 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
         * @method getStart
         * @return { Element } 获得开始元素
         * @example
         * ```javascript
         * editor.selection.getStart();
         * ```
         */
        getStart:function () {
            if ( this._cachedStartElement ) {
                return this._cachedStartElement;
            }
            var range = browser.ie9below ? this.getIERange() : this.getRange(),
                tmpRange,
                start, tmp, parent;
            if ( browser.ie9below ) {
                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
         * @method getText
         * @return { String } 选区中包含的文本
         * @example
         * ```javascript
         * editor.selection.getText();
         * ```
         */
        getText:function () {
            var nativeSel, nativeRange;
            if ( this.isFocus() && (nativeSel = this.getNative()) ) {
                nativeRange = browser.ie9below ? nativeSel.createRange() : nativeSel.getRangeAt( 0 );
                return browser.ie9below ? nativeRange.text : nativeRange.toString();
            }
            return '';
        },

        /**
         * 清除选区
         * @method clearRange
         * @example
         * ```javascript
         * editor.selection.clearRange();
         * ```
         */
        clearRange : function(){
            this.getNative()[browser.ie9below ? 'empty' : 'removeAllRanges']();
        }
    };
})();