var _ = require("underscore");

exports.topLevelElement = topLevelElement;
exports.elements = elements;
exports.element = element;

function topLevelElement(tagName, attributes) {
    return elements([element(tagName, attributes, {fresh: true})]);
}

function elements(elementStyles) {
    return elementStyles.map(function(elementStyle) {
        if (_.isString(elementStyle)) {
            return element(elementStyle);
        } else {
            return elementStyle;
        }
    });
}

function element(tagName, attributes, options) {
    options = options || {};
    return new Element(tagName, attributes, options);
}

function Element(tagName, attributes, options) {
    var tagNames = {};
    if (_.isArray(tagName)) {
        tagName.forEach(function(tagName) {
            tagNames[tagName] = true;
        });
        tagName = tagName[0];
    } else {
        tagNames[tagName] = true;
    }
    
    this.tagName = tagName;
    this.tagNames = tagNames;
    this.attributes = attributes || {};
    this.fresh = options.fresh;
}

Element.prototype.matchesElement = function(element) {
    return this.tagNames[element.tagName] && _.isEqual(this.attributes || {}, element.attributes || {});
};

exports.empty = elements([]);