"use strict"

var buildPathname = require("../pathname/build")
var parsePathname = require("../pathname/parse")
var compileTemplate = require("../pathname/compileTemplate")
var assign = require("../pathname/assign")

module.exports = function($window) {
	var supportsPushState = typeof $window.history.pushState === "function"
	var callAsync = typeof setImmediate === "function" ? setImmediate : setTimeout

	var asyncId
	var router = {prefix: "#!"}
	router.getPath = function() {
		// Consider the pathname holistically. The prefix might even be invalid,
		// but that's not our problem.
		var prefix = $window.location.hash
		if (router.prefix[0] !== "#") {
			prefix = $window.location.search + prefix
			if (router.prefix[0] !== "?") {
				prefix = $window.location.pathname + prefix
				if (prefix[0] !== "/") prefix = "/" + prefix
			}
		}
		// This seemingly useless `.concat()` speeds up the tests quite a bit,
		// since the representation is consistently a relatively poorly
		// optimized cons string.
		return prefix.concat()
			.replace(/(?:%[a-f89][a-f0-9])+/gim, decodeURIComponent)
			.slice(router.prefix.length)
	}

	router.setPath = function(path, data, options) {
		path = buildPathname(path, data)
		if (supportsPushState) {
			var state = options ? options.state : null
			var title = options ? options.title : null
			$window.onpopstate()
			if (options && options.replace) $window.history.replaceState(state, title, router.prefix + path)
			else $window.history.pushState(state, title, router.prefix + path)
		}
		else $window.location.href = router.prefix + path
	}

	router.defineRoutes = function(routes, resolve, reject, defaultRoute) {
		var compiled = Object.keys(routes).map(function(route) {
			if (route.charAt(0) !== "/") throw new SyntaxError("Routes must start with a `/`")
			if ((/:([^\/\.-]+)(\.{3})?:/).test(route)) {
				throw new SyntaxError("Route parameter names must be separated with either `/`, `.`, or `-`")
			}
			return {
				route: route,
				component: routes[route],
				check: compileTemplate(route),
			}
		})

		if (defaultRoute != null) {
			var defaultData = parsePathname(defaultRoute)

			if (!compiled.some(function (i) { return i.check(defaultData) })) {
				throw new ReferenceError("Default route doesn't match any known routes")
			}
		}

		function resolveRoute() {
			var path = router.getPath()
			var data = parsePathname(path)

			assign(data.params, $window.history.state)

			for (var i = 0; i < compiled.length; i++) {
				if (compiled[i].check(data)) {
					resolve(compiled[i].component, data.params, path, compiled[i].route)
					return
				}
			}

			reject(path, data.params)
		}

		if (supportsPushState) {
			$window.onpopstate = function() {
				if (asyncId) return
				asyncId = callAsync(function() {
					asyncId = null
					resolveRoute()
				})
			}
		}
		else if (router.prefix.charAt(0) === "#") $window.onhashchange = resolveRoute
		resolveRoute()
	}

	return router
}