(function($, core, undefined) {

var d_topicData = 'topicData';

core.widget('topic', {
	options: {
		path: '',
		updateTitle: true,
		linkSelector: 'a:not(.service), area:not(.service), .topic-link',
		linkCheck: function(link) {
			var url = link.data('ref') || (link.is('a, area') && core.normalizeHref(link)) || '';
			return (!core.isAbsoluteUrl(url) || link.hasClass('nethelp-link')) && url;
		},
		scriptsFilter: function(i, el) {
			return !/nethelp.redirector.js$/i.test(el.src || '');
		},
		replaceUrlElements: [
			['a, area, link', 'href' ],
			['img, input, embed', 'src'],
			['param[name="movie"]', 'value'],
			['.topic-link', 'data-ref']
		],
		scrollup: {
			margin: 5
		}
	},
	_create: function() {
		var self = this,
			options = self.options,
			element = self.element;
		element.addClass('nethelp-topic');
		element.delegate(options.linkSelector, 'click', function(e) {
			var url = options.linkCheck($(this));
			if (url !== false) {
				e.preventDefault();
				self.load(url);
			}
		});
	},
	html: function(html, event, params) {
		/*
			html: {
				title: 'text',
				body: 'html',
				links: jquery,
				scripts: jquery,
				styles: jquery,
				meta: object
			},
			params: object (extra-params for events),
				params.data: object (add-in information) or false (to remove add-in information)
		*/
		if ($.type(params) !== 'object') {
			params = { data: false };
		}
		var self = this,
			element = self.element,
			ie8 = $.browser.msie && parseInt($.browser.version.charAt(0), 10) < 9,
			r = $.when(),
			f,
			data,
			t,
			els;
		if (html === undefined) {
			return element.html();
		}
		if (!self.trigger('updating', event, params)) {
			return self;
		}
		data = (params === false || params.data === false) ? false : params;
		if (typeof html === 'string') {
			element.html(html);
			html = false;
		}
		if (data && html) {
			els = html.links;
			if (els) {
				if ((t = els.filter('[rel="prev"]')).length) {
					data.prev = t.attr('href');
				}
				if ((t = els.filter('[rel="next"]')).length) {
					data.next = t.attr('href');
				}
				data.links = els;
			}
			data.meta = html.meta || {};
		}
		if (data) {
			element.data(d_topicData, data);
		}
		else {
			element.removeData(d_topicData);
		}
		if (html) {
			if (self.options.updateTitle && 'title' in html) {
				document.title = html.title || 'No title';
			}
			if (!html.inTopic) {
				if (typeof html.body === 'string') {
					element.html(html.body);
				}
				else if (html.body && html.body.jquery) {
					element.html(html.body);
				}
				else if (html.jquery) {
					element.html(html);
				}
				else {
					element.html('');
				}
				t = { auto: 1, scroll: 1 };
				els = element.parents().filter(function() {
					return !!t[$(this).css('overflow-y')];
				});
				(els.length ? els.first() : element).scrollTop(0);
				t = html.styles;
				if (t && t.length) {
					t.each(function() {
						var s = this;
						if (ie8 && s.nodeName.toUpperCase() === 'LINK' && s.href) {
							// IE7-8 required absolute urls
							s.href = core.expandUrl(s.href);
						}
						element.prepend(s);
					});
				}
				t = html.scripts;
				if (t && t.length) {
					t.each(function() {
						var script = this.src;
						if (script) {
							r = r.pipe(f = function() {
								return $.ajax(script, {
									dataType: 'script',
									crossDomain: true,
									cache: true
								});
							}, f);
						}
						else {
							element.append(this);
						}
					});
				}
			}
		}
		self.trigger('update', event, params);
		r.always(function() {
			self.trigger('ready', event, params);
		});
		return self;
	},
	load: function(url, event, params) {
		if (!params || typeof params !== 'object') {
			params = {};
		}
		// parse url ('test.html'|'test.html#header1'|'#header2')
		var self = this,
			element = self.element,
			options = self.options,
			data = element.data(d_topicData),
			t = typeof url === 'string' ? url.split('#') : [],
			query = t[0] || '',
			hash = t[1];
		if (!data) {
			element.data(d_topicData, data = {});
		}

		if (query) {
			if (!self.trigger('loading', event, $.extend({}, params, { url: query }))) {
				return $.when();
			}
			self.abort();
			var loadUrl = core.addUrlSearch(options.path + query, 'nhr=false');
			$.extend(params, {
				url: url,
				query: query,
				hash: hash,
				src: loadUrl
			});
			return self.request = $.ajax({
				url: loadUrl,
				dataType: 'text'
			}).then(function(resp, status, req) {
				var ifr = $('<iframe />').hide().appendTo('body'),
					idoc = ifr[0].contentWindow.document,
					doc = $(idoc),
					loadPath,
					meta = {};
				try {
					idoc.open();
					idoc.write(core.escapeJS(req.responseText));
					idoc.close();
					if (self.trigger('validate', event, $.extend({}, params, { frame: ifr, document: doc }))) {
						t = {
							title: idoc.title,
							baseUrl: doc.find('head base:last').remove().attr('href'),
							scripts: doc.find('script[type="_js"]')
								.remove()
								.map(function() {
									// in native .importNode() in IE9, js will be loaded and executed
									return core.unescapeJSNode(core.importNode(this, { content: 'text', native: false }), true);
								})
								.filter(options.scriptsFilter),
							styles: $($(idoc.createElement('p')).append(doc.find('style').remove()).html())
								.add(doc.find('link[rel~="stylesheet"]').remove().map(function() {
									return core.importNode(this, { native: false, content: false });
								})),
							links: doc.find('link')
								.remove()
								.map(function() {
									return core.importNode(this, { content: false });
								}),
							meta: meta,
							virtualDoc: true,
							src: loadUrl
						};
						doc.find('head title, meta[http-equiv]').remove();
						doc.find('meta[name]').remove().each(function() {
							if (this.name) {
								meta[this.name] = this.value;
							}
						});
						loadPath = core.getUrlPath(loadUrl);
						core.replaceUrls(doc, options.replaceUrlElements, loadPath);
						core.replaceUrls(t.scripts, 'src', loadPath);
						core.replaceUrls(t.links, 'href', loadPath);
						core.replaceUrls(t.styles.filter('link'), 'href', loadPath);
						t.body = doc.find('head').html() + doc.find('body').html();
						doc = t;
						ifr.remove();
						ifr = idoc = undefined;
						params.title = doc.title || params.title || 'No title';
						self.trigger('load', event, params);
						// TODO: (?) load-handler can change params.title
						// if location.hash changes in load-event, title should be set after location.hash change
						params.afterLoad = true;
						self.html(doc, event, params);
						if (hash) {
							self.scrollTo(hash);
						}
					}
				}
				finally {
					ifr && ifr.remove();
				}
			}, function(request, status, error) {
				if (status !== 'abort') {
					element.removeData(d_topicData);
				}
				var d = $.extend({}, params, { status: status, error: error || true, request: request });
				self.trigger('loaderror', event, d);
				self.trigger('load', event, d);
			}).always(function() {
				delete self.request;
			});
		}
		else if (hash) {
			self.scrollTo(hash);
		}
		return $.when();
	},
	scrollTo: function(target) {
		var self = this,
			element = self.element,
			options = self.options.scrollup;
		if (options === false) {
			return self;
		}
		target = typeof target === 'string' ? element.findAnchor(target) : target = $(target);
		if (target && target.scrollup) {
			target.scrollup(options);
		}
		return self;
	},
	abort: function() {
		var request = this.request;
		if (request) {
			request.abort();
		}
	},
	getData: function() {
		return this.element.data(d_topicData);
	}
});

})(jQuery, nethelp);