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Express.ts
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Express.ts
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import { createServer, Server, IncomingMessage as RawIncomingMessage, ServerResponse as RawServerResponse } from "http";
export function express() {
return new App();
}
type RawRequestHandler = (req: RawIncomingMessage, res: RawServerResponse) => void;
interface IncomingMessage extends RawIncomingMessage {
params: { [key: string]: string };
query: { [key: string]: string };
cookies: { [key: string]: string };
body?: any;
}
interface ServerResponse extends RawServerResponse {
status(status: number): ServerResponse;
header(header: { [key: string]: string }): ServerResponse;
body(body: string): void;
}
type RequestHandler = (req: IncomingMessage, res: ServerResponse) => Promise<void> | void;
function zipMax<T, R>(left: T[], right: R[]): { left: T, right?: R }[] {
return zipLength(left, right, Math.max(left.length, right.length));
}
function zipMin<T, R>(left: T[], right: R[]): { left: T, right: R }[] {
return zipLength(left, right, Math.min(left.length, right.length));
}
function zipLength<T, R>(left: T[], right: R[], length: number): { left: T, right: R }[] {
const dst = [];
for (let i = 0; i < length; i++) {
dst.push({
left: left[i],
right: right[i],
});
}
return dst;
}
function trimSlash(input: string) {
input = input.startsWith("/") ? input.slice(1) : input;
input = input.endsWith("/") ? input.slice(0, -1) : input;
return input;
}
function hasFitsUrl(defined: string, incoming: string): boolean {
return zipMax(trimSlash(defined).split("/"), trimSlash(incoming)
.split("/")).every(({ left, right }) => {
if (left === right) {
return true;
}
if (left == null || right == null) {
return false;
}
if (left.startsWith(":")) {
return true;
}
return false;
});
}
function getSimilarityUrl(defined: string, incoming: string): number {
const r = zipMax(trimSlash(defined).split("/"), trimSlash(incoming)
.split("/")).reduce<number>((prev, { left, right }) => {
if (right == null) {
return prev;
}
if (left === right) {
return prev + 1;
}
if (left.startsWith(":")) {
return prev + 1;
}
return prev;
}, 0);
return r
}
function getParams(defined: string, incoming: string): { [key: string]: string } {
return zipMin(trimSlash(defined).split("/"), trimSlash(incoming).split("/"))
.reduce((prev, { left, right }) =>
left.startsWith(":")
? ({ ...prev, [left.slice(1)]: right })
: prev,
{}
);
}
function wrapAsIncomingMessage(message: RawIncomingMessage, params: any, query: any, cookies: any, body?: any): IncomingMessage {
const dst = {
...message,
params, query, cookies, body
} as IncomingMessage;
(dst as any).__proto__ = (message as any).__proto__;
return dst;
}
function wrapAsServerResponse(response: RawServerResponse): ServerResponse {
const dst: ServerResponse = {
...response,
status(status: number) {
response.statusCode = status;
return wrapAsServerResponse(response);
},
header(header: { [key: string]: string }) {
Object.entries(header).forEach(([key, value]) => response.setHeader(key, value));
return wrapAsServerResponse(response);
},
body(body: string) {
response.end(body);
},
end(buf: Buffer) {
response.end(buf);
}
} as unknown as ServerResponse;
(dst as any).__proto__ = (response as any).__proto__;
return dst;
}
function parseQuery(queryString: string) {
return queryString.split("&")
.map(item => item.trim())
.filter(item => item !== "")
.map(item => item.split("="))
.reduce((prev, [key, value]) => ({ ...prev, [key]: value }), {});
}
async function parseBody(req: RawIncomingMessage): Promise<any> {
let result = "";
return new Promise(ok => {
req.on("data", data => result = result + data.toString());
req.on("end", () => {
try {
ok(JSON.parse(result));
} catch {
console.error(`Failed to parse body by json. This framework expect json body.: ${result}`);
ok(result);
}
});
});
}
function parseCookie(cookieString: string) {
return cookieString.split(";")
.map(item => item.trim())
.filter(item => item !== "")
.map(item => item.split("="))
.reduce((prev, [key = "", value = ""]) => ({ ...prev, [key]: value }), {});
}
class App {
server: Server;
callbacks: {
method: string;
path: string;
handler: RequestHandler;
}[] = [];
constructor() {
this.server = createServer(this.handle);
}
handle = async (req: RawIncomingMessage, res: RawServerResponse) => {
try {
const url = req.url ?? "";
const [path = "", queryString = ""] = url.split("?")
const founds = this.callbacks
.filter(it => it.method === (req.method ?? "").toUpperCase())
.filter(it => hasFitsUrl(it.path, path));
if (founds.length === 0) {
res.writeHead(404)
return res.end();
}
let body = {};
if (req.method?.toUpperCase() === "POST" || req.method?.toUpperCase() === "PUT") {
body = await parseBody(req);
}
const found = founds.sort((a, b) =>
getSimilarityUrl(b.path, path) - getSimilarityUrl(a.path, path))[0];
await found.handler(
wrapAsIncomingMessage(req, getParams(found.path, path), parseQuery(queryString), parseCookie(req.headers.cookie ?? ""), body),
wrapAsServerResponse(res)
);
} catch (e: unknown) {
res.writeHead(500)
return res.end((e as Error).stack);
}
}
async listen(port: number): Promise<App> {
return new Promise(ok =>
this.server.listen(port, () => ok(this))
);
}
use(method: string, path: string, handler: RequestHandler) {
this.callbacks.push({
method: method.toUpperCase(),
path,
handler,
});
}
get(path: string, handler: RequestHandler) {
this.use("get", path, handler);
}
post(path: string, handler: RequestHandler) {
this.use("post", path, handler);
}
put(path: string, handler: RequestHandler) {
this.use("put", path, handler);
}
close() {
this.server.close();
}
}