/**
 * @author Ed Spencer
 * @class Ext.data.writer.Xml
 *
 * This class is used to write {@link Ext.data.Model} data to the server in an XML format.
 * The {@link #documentRoot} property is used to specify the root element in the XML document.
 * The {@link #record} option is used to specify the element name for each record that will make
 * up the XML document.
 */
Ext.define('Ext.data.writer.Xml', {

    /* Begin Definitions */

    extend: 'Ext.data.writer.Writer',
    alternateClassName: 'Ext.data.XmlWriter',

    alias: 'writer.xml',

    /* End Definitions */

    config: {
        /**
         * @cfg {String} documentRoot The name of the root element of the document.
         * If there is more than 1 record and the root is not specified, the default document root will still be used
         * to ensure a valid XML document is created.
         */
        documentRoot: 'xmlData',

        /**
         * @cfg {String} defaultDocumentRoot The root to be used if {@link #documentRoot} is empty and a root is required
         * to form a valid XML document.
         */
        defaultDocumentRoot: 'xmlData',

        /**
         * @cfg {String} header A header to use in the XML document (such as setting the encoding or version).
         */
        header: '',

        /**
         * @cfg {String} record The name of the node to use for each record.
         */
        record: 'record'
    },

    /**
     * @param {Object} request
     * @param {Array} data
     * @return {Object}
     */
    writeRecords: function(request, data) {
        var me = this,
            xml = [],
            i = 0,
            len = data.length,
            root = me.getDocumentRoot(),
            record = me.getRecord(),
            needsRoot = data.length !== 1,
            item,
            key;

        // may not exist
        xml.push(me.getHeader() || '');

        if (!root && needsRoot) {
            root = me.getDefaultDocumentRoot();
        }

        if (root) {
            xml.push('<', root, '>');
        }

        for (; i < len; ++i) {
            item = data[i];
            xml.push('<', record, '>');
            for (key in item) {
                if (item.hasOwnProperty(key)) {
                    xml.push('<', key, '>', item[key], '</', key, '>');
                }
            }
            xml.push('</', record, '>');
        }

        if (root) {
            xml.push('</', root, '>');
        }

        request.setXmlData(xml.join(''));
        return request;
    }
});
