/*

Copyright (c) 2009, Yahoo! Inc. All rights reserved.

Code licensed under the BSD License:

http://developer.yahoo.net/yui/license.txt

version: 3.0.0

build: 1549

*/

YUI.add('dataschema-xml', function(Y) {

/**

 * Provides a DataSchema implementation which can be used to work with XML data.

 *

 * @module dataschema

 * @submodule dataschema-xml

 */

var LANG = Y.Lang,

    /**

     * XML subclass for the DataSchema Utility.

     * @class DataSchema.XML

     * @extends DataSchema.Base

     * @static

     */

    SchemaXML = {

        /////////////////////////////////////////////////////////////////////////////

        //

        // DataSchema.XML static methods

        //

        /////////////////////////////////////////////////////////////////////////////

        /**

         * Applies a given schema to given XML data.

         *

         * @method apply

         * @param schema {Object} Schema to apply.

         * @param data {XMLDoc} XML document.

         * @return {Object} Schema-parsed data.

         * @static

         */

        apply: function(schema, data) {

            var xmldoc = data,

                data_out = {results:[],meta:{}};

            if(xmldoc && xmldoc.nodeType && (xmldoc.nodeType === 9 || xmldoc.nodeType === 1 || xmldoc.nodeType === 11) && schema) {

                // Parse results data

                data_out = SchemaXML._parseResults(schema, xmldoc, data_out);

                // Parse meta data

                data_out = SchemaXML._parseMeta(schema.metaFields, xmldoc, data_out);

            }

            else {

                data_out.error = new Error("XML schema parse failure");

            }

            return data_out;

        },

        /**

         * Get an XPath-specified value for a given field from an XML node or document.

         *

         * @method _getLocationValue

         * @param field {String | Object} Field definition.

         * @param context {Object} XML node or document to search within.

         * @return {Object} Data value or null.

         * @static

         * @protected

         */

        _getLocationValue: function(field, context) {

            var locator = field.locator || field.key || field,

                xmldoc = context.ownerDocument || context,

                result, res, value = null;

            try {

                // Standards mode

                if(!LANG.isUndefined(xmldoc.evaluate)) {

                    result = xmldoc.evaluate(locator, context, xmldoc.createNSResolver(!context.ownerDocument ? context.documentElement : context.ownerDocument.documentElement), 0, null);

                    while(res = result.iterateNext()) {

                        value = res.textContent;

                    }

                }

                // IE mode

                else {

                    xmldoc.setProperty("SelectionLanguage", "XPath");

                    result = context.selectNodes(locator)[0];

                    value = result.value || result.text || null;

                }

                return Y.DataSchema.Base.parse(value, field);

            }

            catch(e) {

            }

        },

        /**

         * Parses results data according to schema

         *

         * @method _parseMeta

         * @param xmldoc_in {Object} XML document parse.

         * @param data_out {Object} In-progress schema-parsed data to update.

         * @return {Object} Schema-parsed data.

         * @static

         * @protected

         */

        _parseMeta: function(metaFields, xmldoc_in, data_out) {

            if(LANG.isObject(metaFields)) {

                var key,

                    xmldoc = xmldoc_in.ownerDocument || xmldoc_in;

                for(key in metaFields) {

                    if (metaFields.hasOwnProperty(key)) {

                        data_out.meta[key] = SchemaXML._getLocationValue(metaFields[key], xmldoc);

                    }

                }

            }

            return data_out;

        },

        /**

         * Schema-parsed list of results from full data

         *

         * @method _parseResults

         * @param schema {Object} Schema to parse against.

         * @param xmldoc_in {Object} XML document parse.

         * @param data_out {Object} In-progress schema-parsed data to update.

         * @return {Object} Schema-parsed data.

         * @static

         * @protected

         */

        _parseResults: function(schema, xmldoc_in, data_out) {

            if(schema.resultListLocator && LANG.isArray(schema.resultFields)) {

                var nodeList = xmldoc_in.getElementsByTagName(schema.resultListLocator),

                    fields = schema.resultFields,

                    results = [],

                    node, field, result, i, j;

                if(nodeList.length) {

                    // Loop through each result node

                    for(i=nodeList.length-1; i>= 0; i--) {

                        result = {};

                        node = nodeList[i];

                        // Find each field value

                        for(j=fields.length-1; j>= 0; j--) {

                            field = fields[j];

                            result[field.key || field] = SchemaXML._getLocationValue(field, node);

                        }

                        results[i] = result;

                    }

                    data_out.results = results;

                }

                else {

                    data_out.error = new Error("XML schema result nodes retrieval failure");

                }

            }

            return data_out;

        }

    };

Y.DataSchema.XML = Y.mix(SchemaXML, Y.DataSchema.Base);

}, '3.0.0' ,{requires:['dataschema-base']});