/**
 * Adds HTML Parser support to the base Widget class
 *
 * @module widget
 * @submodule widget-htmlparser
 * @for Widget
 */

var Widget = Y.Widget,
    Node = Y.Node,
    Lang = Y.Lang,

    SRC_NODE = "srcNode",
    CONTENT_BOX = "contentBox";

/**
 * Object hash, defining how attribute values are to be parsed from
 * markup contained in the widget's content box. e.g.:
 * <pre>
 *   {
 *       // Set single Node references using selector syntax
 *       // (selector is run through node.one)
 *       titleNode: "span.yui-title",
 *       // Set NodeList references using selector syntax
 *       // (array indicates selector is to be run through node.all)
 *       listNodes: ["li.yui-item"],
 *       // Set other attribute types, using a parse function.
 *       // Context is set to the widget instance.
 *       label: function(contentBox) {
 *           return contentBox.one("span.title").get("innerHTML");
 *       }
 *   }
 * </pre>
 *
 * @property HTML_PARSER
 * @type Object
 * @static
 */
Widget.HTML_PARSER = {};

/**
 * The build configuration for the Widget class.
 * <p>
 * Defines the static fields which need to be aggregated,
 * when this class is used as the main class passed to
 * the <a href="Base.html#method_build">Base.build</a> method.
 * </p>
 * @property _buildCfg
 * @type Object
 * @static
 * @final
 * @private
 */
Widget._buildCfg = {
    aggregates : ["HTML_PARSER"]
};

/**
 * The DOM node to parse for configuration values, passed to the Widget's HTML_PARSER definition
 *
 * @attribute srcNode
 * @type String | Node
 * @writeOnce
 */
Widget.ATTRS[SRC_NODE] = {
    value: null,
    setter: Node.one,
    getter: "_getSrcNode",
    writeOnce: true
};

Y.mix(Widget.prototype, {

    /**
     * @method _getSrcNode
     * @protected
     * @return {Node} The Node to apply HTML_PARSER to
     */
    _getSrcNode : function(val) {
        return val || this.get(CONTENT_BOX);
    },

    /**
     * Implement the BaseCore _preAddAttrs method hook, to add
     * the srcNode and related attributes, so that HTML_PARSER
     * (which relies on `this.get("srcNode")`) can merge in it's
     * results before the rest of the attributes are added.
     *
     * @method _preAddAttrs
     * @protected
     *
     * @param attrs {Object} The full hash of statically defined ATTRS
     * attributes being added for this instance
     *
     * @param userVals {Object} The hash of user values passed to
     * the constructor
     *
     * @param lazy {boolean} Whether or not to add the attributes lazily
     */
    _preAddAttrs : function(attrs, userVals, lazy) {

        var preAttrs = {
            id : attrs.id,
            boundingBox : attrs.boundingBox,
            contentBox : attrs.contentBox,
            srcNode : attrs.srcNode
        };

        this.addAttrs(preAttrs, userVals, lazy);

        delete attrs.boundingBox;
        delete attrs.contentBox;
        delete attrs.srcNode;
        delete attrs.id;

        if (this._applyParser) {
            this._applyParser(userVals);
        }
    },

    /**
     * @method _applyParsedConfig
     * @protected
     * @return {Object} The merged configuration literal
     */
    _applyParsedConfig : function(node, cfg, parsedCfg) {
        return (parsedCfg) ? Y.mix(cfg, parsedCfg, false) : cfg;
    },

    /**
     * Utility method used to apply the <code>HTML_PARSER</code> configuration for the
     * instance, to retrieve config data values.
     *
     * @method _applyParser
     * @protected
     * @param config {Object} User configuration object (will be populated with values from Node)
     */
    _applyParser : function(config) {

        var widget = this,
            srcNode = this._getNodeToParse(),
            schema = widget._getHtmlParser(),
            parsedConfig,
            val;

        if (schema && srcNode) {
            Y.Object.each(schema, function(v, k, o) {
                val = null;

                if (Lang.isFunction(v)) {
                    val = v.call(widget, srcNode);
                } else {
                    if (Lang.isArray(v)) {
                        val = srcNode.all(v[0]);
                        if (val.isEmpty()) {
                            val = null;
                        }
                    } else {
                        val = srcNode.one(v);
                    }
                }

                if (val !== null && val !== undefined) {
                    parsedConfig = parsedConfig || {};
                    parsedConfig[k] = val;
                }
            });
        }
        config = widget._applyParsedConfig(srcNode, config, parsedConfig);
    },

    /**
     * Determines whether we have a node reference which we should try and parse.
     *
     * The current implementation does not parse nodes generated from CONTENT_TEMPLATE,
     * only explicitly set srcNode, or contentBox attributes.
     *
     * @method _getNodeToParse
     * @return {Node} The node reference to apply HTML_PARSER to.
     * @private
     */
    _getNodeToParse : function() {
        var srcNode = this.get("srcNode");
        return (!this._cbFromTemplate) ? srcNode : null;
    },

    /**
     * Gets the HTML_PARSER definition for this instance, by merging HTML_PARSER
     * definitions across the class hierarchy.
     *
     * @private
     * @method _getHtmlParser
     * @return {Object} HTML_PARSER definition for this instance
     */
    _getHtmlParser : function() {
        // Removed caching for kweight. This is a private method
        // and only called once so don't need to cache HTML_PARSER
        var classes = this._getClasses(),
            parser = {},
            i, p;

        for (i = classes.length - 1; i >= 0; i--) {
            p = classes[i].HTML_PARSER;
            if (p) {
                Y.mix(parser, p, true);
            }
        }
        return parser;
    }
});