var index = require("./index.js"),
    DomHandler = index.DomHandler,
    DomUtils = index.DomUtils;

//TODO: make this a streamable handler
function FeedHandler(callback, options){
	this.init(callback, options);
}

require("inherits")(FeedHandler, DomHandler);

FeedHandler.prototype.init = DomHandler;

function getElements(what, where){
	return DomUtils.getElementsByTagName(what, where, true);
}
function getOneElement(what, where){
	return DomUtils.getElementsByTagName(what, where, true, 1)[0];
}
function fetch(what, where, recurse){
	return DomUtils.getText(
		DomUtils.getElementsByTagName(what, where, recurse, 1)
	).trim();
}

function addConditionally(obj, prop, what, where, recurse){
	var tmp = fetch(what, where, recurse);
	if(tmp) obj[prop] = tmp;
}

var isValidFeed = function(value){
	return value === "rss" || value === "feed" || value === "rdf:RDF";
};

FeedHandler.prototype.onend = function(){
	var feed = {},
	    feedRoot = getOneElement(isValidFeed, this.dom),
	    tmp, childs;

	if(feedRoot){
		if(feedRoot.name === "feed"){
			childs = feedRoot.children;

			feed.type = "atom";
			addConditionally(feed, "id", "id", childs);
			addConditionally(feed, "title", "title", childs);
			if((tmp = getOneElement("link", childs)) && (tmp = tmp.attribs) && (tmp = tmp.href)) feed.link = tmp;
			addConditionally(feed, "description", "subtitle", childs);
			if((tmp = fetch("updated", childs))) feed.updated = new Date(tmp);
			addConditionally(feed, "author", "email", childs, true);

			feed.items = getElements("entry", childs).map(function(item){
				var entry = {}, tmp;

				item = item.children;

				addConditionally(entry, "id", "id", item);
				addConditionally(entry, "title", "title", item);
				if((tmp = getOneElement("link", item)) && (tmp = tmp.attribs) && (tmp = tmp.href)) entry.link = tmp;
				if((tmp = fetch("summary", item) || fetch("content", item))) entry.description = tmp;
				if((tmp = fetch("updated", item))) entry.pubDate = new Date(tmp);
				return entry;
			});
		} else {
			childs = getOneElement("channel", feedRoot.children).children;

			feed.type = feedRoot.name.substr(0, 3);
			feed.id = "";
			addConditionally(feed, "title", "title", childs);
			addConditionally(feed, "link", "link", childs);
			addConditionally(feed, "description", "description", childs);
			if((tmp = fetch("lastBuildDate", childs))) feed.updated = new Date(tmp);
			addConditionally(feed, "author", "managingEditor", childs, true);

			feed.items = getElements("item", feedRoot.children).map(function(item){
				var entry = {}, tmp;

				item = item.children;

				addConditionally(entry, "id", "guid", item);
				addConditionally(entry, "title", "title", item);
				addConditionally(entry, "link", "link", item);
				addConditionally(entry, "description", "description", item);
				if((tmp = fetch("pubDate", item))) entry.pubDate = new Date(tmp);
				return entry;
			});
		}
	}
	this.dom = feed;
	DomHandler.prototype._handleCallback.call(
		this, feedRoot ? null : Error("couldn't find root of feed")
	);
};

module.exports = FeedHandler;