/* global _ */
(function () {
	'use strict'

	/* jshint ignore:start */
	// Underscore's Template Module
	// Courtesy of underscorejs.org
	var _ = (function (_) {
		_.defaults = function (object) {
			if (!object) {
				return object
			}
			for (var argsIndex = 1, argsLength = arguments.length; argsIndex < argsLength; argsIndex++) {
				var iterable = arguments[argsIndex]
				if (iterable) {
					for (var key in iterable) {
						if (object[key] == null) {
							object[key] = iterable[key]
						}
					}
				}
			}
			return object
		}

		// By default, Underscore uses ERB-style template delimiters, change the
		// following template settings to use alternative delimiters.
		_.templateSettings = {
			evaluate    : /<%([\s\S]+?)%>/g,
			interpolate : /<%=([\s\S]+?)%>/g,
			escape      : /<%-([\s\S]+?)%>/g
		}

		// When customizing `templateSettings`, if you don't want to define an
		// interpolation, evaluation or escaping regex, we need one that is
		// guaranteed not to match.
		var noMatch = /(.)^/

		// Certain characters need to be escaped so that they can be put into a
		// string literal.
		var escapes = {
			"'":      "'",
			"\\":     "\\",
			"\r":     "r",
			"\n":     "n",
			"\t":     "t",
			"\u2028": "u2028",
			"\u2029": "u2029"
		}

		var escaper = /\\|'|\r|\n|\t|\u2028|\u2029/g

		// JavaScript micro-templating, similar to John Resig's implementation.
		// Underscore templating handles arbitrary delimiters, preserves whitespace,
		// and correctly escapes quotes within interpolated code.
		_.template = function (text, data, settings) {
			var render
			settings = _.defaults({}, settings, _.templateSettings)

			// Combine delimiters into one regular expression via alternation.
			var matcher = new RegExp([
				(settings.escape || noMatch).source,
				(settings.interpolate || noMatch).source,
				(settings.evaluate || noMatch).source
			].join("|") + "|$", "g")

			// Compile the template source, escaping string literals appropriately.
			var index = 0
			var source = "__p+='"
			text.replace(matcher, function (match, escape, interpolate, evaluate, offset) {
				source += text.slice(index, offset)
					.replace(escaper, function (match) { return "\\" + escapes[match] })

				if (escape) {
					source += "'+\n((__t=(" + escape + "))==null?'':_.escape(__t))+\n'"
				}
				if (interpolate) {
					source += "'+\n((__t=(" + interpolate + "))==null?'':__t)+\n'"
				}
				if (evaluate) {
					source += "';\n" + evaluate + "\n__p+='"
				}
				index = offset + match.length
				return match
			})
			source += "';\n"

			// If a variable is not specified, place data values in local scope.
			if (!settings.variable) source = "with(obj||{}){\n" + source + '}\n'

			source = "var __t,__p='',__j=Array.prototype.join," +
				"print=function(){__p+=__j.call(arguments,'');};\n" +
				source + "return __p;\n"

			try {
				render = new Function(settings.variable || "obj", "_", source)
			} catch (e) {
				e.source = source
				throw e
			}

			if (data) return render(data, _)
			var template = function (data) {
				return render.call(this, data, _)
			}

			// Provide the compiled function source as a convenience for precompilation.
			template.source = "function(" + (settings.variable || "obj") + "){\n" + source + '}'

			return template
		}

		return _
	})({})

	if (location.hostname === "todomvc.com") {
		(function (i, s, o, g, r, a, m){ i["GoogleAnalyticsObject"] = r;i[r] = i[r]|| function (){
			(i[r].q = i[r].q || []).push(arguments) }, i[r].l = 1 * new Date();a = s.createElement(o),
		m = s.getElementsByTagName(o)[0];a.async = 1;a.src = g;m.parentNode.insertBefore(a, m)
		})(window, document,"script","https://www.google-analytics.com/analytics.js","ga")
		ga("create", "UA-31081062-1", "auto")
		ga("send", "pageview")
	}
	/* jshint ignore:end */

	function redirect() {
		if (location.hostname === "tastejs.github.io") {
			location.href = location.href.replace("tastejs.github.io/todomvc", "todomvc.com")
		}
	}

	function findRoot() {
		var base = location.href.indexOf("examples/")
		return location.href.substr(0, base)
	}

	function getFile(file, callback) {
		if (!location.host) {
			return console.info("Miss the info bar? Run TodoMVC from a server to avoid a cross-origin error.")
		}

		var xhr = new XMLHttpRequest()

		xhr.open("GET", findRoot() + file, true)
		xhr.send()

		xhr.onload = function () {
			if (xhr.status === 200 && callback) {
				callback(xhr.responseText)
			}
		}
	}

	function Learn(learnJSON, config) {
		if (!(this instanceof Learn)) {
			return new Learn(learnJSON, config)
		}

		var template, framework

		if (typeof learnJSON !== "object") {
			try {
				learnJSON = JSON.parse(learnJSON)
			} catch (e) {
				return
			}
		}

		if (config) {
			template = config.template
			framework = config.framework
		}

		if (!template && learnJSON.templates) {
			template = learnJSON.templates.todomvc
		}

		if (!framework && document.querySelector("[data-framework]")) {
			framework = document.querySelector("[data-framework]").dataset.framework
		}

		this.template = template

		if (learnJSON.backend) {
			this.frameworkJSON = learnJSON.backend
			this.frameworkJSON.issueLabel = framework
			this.append({
				backend: true
			})
		} else if (learnJSON[framework]) {
			this.frameworkJSON = learnJSON[framework]
			this.frameworkJSON.issueLabel = framework
			this.append()
		}

		this.fetchIssueCount()
	}

	Learn.prototype.append = function (opts) {
		var aside = document.createElement("aside")
		aside.innerHTML = _.template(this.template, this.frameworkJSON)
		aside.className = 'learn'

		if (opts && opts.backend) {
			// Remove demo link
			var sourceLinks = aside.querySelector(".source-links")
			var heading = sourceLinks.firstElementChild
			var sourceLink = sourceLinks.lastElementChild
			// Correct link path
			var href = sourceLink.getAttribute("href")
			sourceLink.setAttribute("href", href.substr(href.lastIndexOf("http")))
			sourceLinks.innerHTML = heading.outerHTML + sourceLink.outerHTML
		} else {
			// Localize demo links
			var demoLinks = aside.querySelectorAll(".demo-link")
			Array.prototype.forEach.call(demoLinks, function (demoLink) {
				if (demoLink.getAttribute("href").substr(0, 4) !== "http") {
					demoLink.setAttribute("href", findRoot() + demoLink.getAttribute("href"))
				}
			})
		}

		document.body.className = (document.body.className + " learn-bar").trim()
		document.body.insertAdjacentHTML("afterBegin", aside.outerHTML)
	}

	Learn.prototype.fetchIssueCount = function () {
		var issueLink = document.getElementById("issue-count-link")
		if (issueLink) {
			var url = issueLink.href.replace("https://github.com", "https://api.github.com/repos")
			var xhr = new XMLHttpRequest()
			xhr.open("GET", url, true)
			xhr.onload = function (e) {
				var parsedResponse = JSON.parse(e.target.responseText)
				if (parsedResponse instanceof Array) {
					var count = parsedResponse.length
					if (count !== 0) {
						issueLink.innerHTML = "This app has " + count + ' open issues'
						document.getElementById("issue-count").style.display = 'inline'
					}
				}
			}
			xhr.send()
		}
	}

	redirect()
	getFile("learn.json", Learn)
})()