var http = require("http");
var urllib = require("url");
var fs = require("fs");

var res404 = "404 not found: {{method}} {{pathname}}";
var res403 = "403 forbidden: {{method}} {{pathname}}";

function template(tpml, args) {
	for (var i in args) {
		tpml = tpml.split("{{"+i+"}}").join(args[i]);
	}
	return tpml;
}

function resJson(obj) {
	this.writeHead(200, {
		"content-type": "application/json"
	});
	this.end(JSON.stringify(obj));
}

function methodsMatch(route, req) {
	if (route.method === "ALL")
		return true;
	if (route.method === "GET" && req.method === "HEAD")
		return true;
	return route.method === req.method;
}

class App {
	constructor(options) {
		options = options || {};

		// 403 and 404 response
		this.res404 = options.res404 || res404;
		this.res403 = options.res403 || res403;

		// Script to be served as /webframe.js
		this.clientScript = "";

		// Create server
		if (options.server !== undefined) {
			this.server = options.server;
		} else {
			this.server = http.createServer();
		}

		// Listen
		if (options.listen !== false) {
			var port = options.port || process.env.PORT || 8080;
			var host = options.host || process.env.HOSTNAME || "127.0.0.1";

			this.server.listen(port, host);
			this.info("Listening on "+host+":"+port);
			this.port = port;
			this.host = host;
		}

		this._routeMap = {};
		this._routes = [];
		this._transforms = {};

		// Add scripts
		if (options.client_utils) {
			this.addScript("client_utils",
				fs.readFileSync(__dirname+"/client/utils.js", "utf8"));
		}

		// Serve /webframe.js
		this.get("/webframe.js", (req, res) => {
			res.writeHead(200, {
				"Content-Type": "application/javascript"
			});
			res.end(this.clientScript);
		});

		// Listen for requests
		this.server.on("request", (req, res) => {
			res.json = resJson;
			var url = urllib.parse(req.url);
			req.urlobj = url;

			var route = null;

			// With HEAD requests, we don't want to write anything
			if (req.method === "HEAD") {
				res.write = function() {};
				var end = res.end;
				res.end = function() { end.call(res); }
			}

			// If the route is in the hash map, use that
			var r = this._routeMap[url.pathname];
			if (r && (methodsMatch(r, req))) {
				route = r;

			// Search through the routes list and look for matching routes
			} else {
				for (var i in this._routes) {
					var r = this._routes[i];
					if (!methodsMatch(r, req))
						continue;

					if (r.pattern.test(req.urlobj.pathname)) {
						route = r;
						break;
					}
				}
			}

			// If we still have no route, 404
			if (route === null) {
				res.writeHead(404);
				res.end(template(this.res404,
					{ method: req.method, pathname: req.urlobj.pathname }));
				return;
			}

			// Run all the middleware stuff if applicable
			var self = this;
			if (route.middleware && route.middleware.length > 0) {
				var cbs = route.middleware.length;
				function cb() {
					if (--cbs === 0)
						route.func(req, res, self);
					else
						route.middleware.shift()(req, res, cb);
				}

				route.middleware.shift()(req, res, cb);

			// Just run the function if there's no middleware
			} else {
				route.func(req, res, this);
			}
		});
	}

	/*
	 * Add route.
	 * Args:
	 *     method: "GET", "POST", "PUT", "DELETE", "ALL"
	 *     path: path,
	 *     middleware: middleware array (optional)
	 *     func: function(request, response)
	 */
	route(method, path, middleware, func) {
		if (method !== "GET" && method !== "POST" && method !== "PUT" &&
				method !== "DELETE" && method !== "ALL") {
			throw new Error("Invalid method.");
		}

		// Middleware is optional
		if (func === undefined) {
			func = middleware;
			middleware = undefined;
		}

		// All necessary arguments must exist
		if (typeof path !== "string")
			throw new TypeError("Path must be a string.");
		if (typeof func !== "function")
			throw new TypeError("Func must be a function.");

		// All middlewares must exist
		if (middleware) {
			for (var i in middleware) {
				if (typeof middleware[i] !== "function") {
					this.panic(
						"Middleware "+i+" for "+method+" "+path+
						" is "+(typeof middleware[i])+", expected function.");
					return;
				}
			}
		}

		// Add to routes array or route map
		if (path[0] === "^") {
			var pat = new RegExp(path);
			this._routes.push({
				method: method,
				func: func,
				pattern: pat,
				middleware: middleware
			});
		} else  {
			this._routeMap[path] = {
				method: method,
				func: func,
				middleware: middleware
			};
		}
	}

	/*
	 * Remove a route.
	 * Args:
	 *     path: path
	 */
	unroute(path) {
		if (path[0] === "^") {
			path = "/"+path+"/";
			for (var i in this._routes) {
				var str = this._routes[i].pattern.toString();
				if (path === str)
					delete this._routes[i];
			}
		} else {
			delete this._routeMap[path];
		}
	}

	/*
	 * Add a transform.
	 * Args:
	 *     ext: What extension to transform
	 *     mime: The mime-type the transformed code should be sent as
	 *     func: function(path, writeStream)
	 *
	 * writeStream: {
	 *     status: status code (should only be modified before write() or end())
	 *     headers: HTTP headers (should only be modified before write() or end())
	 *     write: function(data) - write data
	 *     end: function(data) - write data and end response
	 *     error: function(err) - end response and log error
	 * }
	 */
	transform(ext, mime, func) {
		if (typeof ext !== "string")
			throw new Error("Expected ext to be string, got "+(typeof ext)+".");
		if (typeof func !== "function")
			throw new Error("Expected func to be function, got "+(typeof func)+".");
		if (this._transforms[ext])
			throw new Error("Extension "+ext+" already has a transform.");

		this._transforms[ext] = {
			func: func,
			mime: mime
		};
	}

	/*
	 * Add code to be served as /webframe.js
	 */
	addScript(name, str) {
		var start = "(function "+name+"() {\n";
		var end = "\n})();\n"

		str = str.trim();
		this.clientScript += start + str + end;
	}

	/*
	 * Template string
	 */
	template(tmpl, args) { return template(tmpl, args); }

	/*
	 * Utility methods for GET/POST/PUT/DELETE/ALL
	 */
	get(path, middleware, func) { this.route("GET", path, middleware, func); }
	post(path, middleware, func) { this.route("POST", path, middleware, func); }
	put(path, middleware, func) { this.route("PUT", path, middleware, func); }
	delete(path, middleware, func) { this.route("DELETE", path, middleware, func); }
	all(path, middleware, func) { this.route("ALL", path, middleware, func); }

	/*
	 * Logging
	 */
	info(str) {
		console.log("Info: "+str);
	}
	notice(str) {
		console.log("Notice: "+str);
	}
	warning(str) {
		console.log("Warning: "+str);
	}
	panic(str) {
		console.log("PANIC: "+str);
		process.exit(1);
	}
}

exports.static = require("./js/static");
exports.middleware = require("./js/middleware");;
exports.App = App;