clonegur/backend/server/Router.ts

import { Reflect } from "https://deno.land/x/reflect_metadata@v0.1.12/mod.ts";
import serialize from "./serialize.ts";
import HttpError from "./HttpError.ts";
import RestResponse from "./RestResponse.ts";
import RestRequest from "./RestRequest.ts";

export type HandlerRes = Promise<RestResponse | undefined> | RestResponse | undefined;

export interface Handler {
    handle(req: RestRequest): HandlerRes;
}
export interface RestOptions {
    route?: string;
}

// deno-lint-ignore no-explicit-any
export type ProcessFunc<T extends Router> = (this: T, req: RestRequest, arg: any, name: string) => Promise<unknown> | unknown;

export interface RouterHandler {
    path: string;
    handler: Handler;
}
export function addMetaQuery<T extends Router>(target: T, ...handlers: ((r: T) => RouterHandler)[]) {
    let props = Reflect.getOwnMetadata('router:queries', target);
    if (props === undefined) Reflect.defineMetadata('router:queries', props = [], target);

    props.push(...handlers);
}

export function makeParameterModifier<T extends Router>(func: ProcessFunc<T>) {
    return (target: T, key: string, index: number) => {
        let res = Reflect.getOwnMetadata('router:params', target, key);

        if (res === undefined) Reflect.defineMetadata('router:params', res = [], target, key);
        (res[index] ??= []).push(func);

        return res;
    }
}


export default class Router {
    private _handlers?: RouterHandler[];
    public defaultHandler?: Handler;

    private _init() {
        if (this._handlers === undefined) {
            this._handlers = [];

            // why the actual fuck not
            // deno-lint-ignore no-this-alias
            for (let proto = this; proto instanceof Router; proto = Object.getPrototypeOf(proto)) {
                const props = Reflect.getOwnMetadata('router:queries', proto);
                for (const handler of props ?? []) {
                    this._handlers.push(handler(this));
                }
            }
        }
        return this._handlers;
    }

    public async handle(req: RestRequest) {
        for (const hnd of this._init()) {
            const _req = req.match(hnd.path);
            if (_req) {
                try {
                    const res = await hnd.handler.handle(_req);
                    if (res) {
                        // damn you cors
                        res.header('Access-Control-Allow-Origin', '*')
                        res.header('Access-Control-Allow-Headers', '*')
                        return res;
                    }
                }
                catch (e) {
                    const res = await this.onError(_req, e);
                    if (res instanceof HttpError) return new RestResponse()
                        .body(await serialize(res.body))
                        .status(res.status);
                    else return res;
                }
            }
        }

        return this.defaultHandler?.handle(req);
    }
    public addHandler(path: string, handler: Handler) {
        this._init().push({ path, handler });
        return this;
    }

    public onError(_req: RestRequest, error: unknown): Promise<RestResponse | HttpError> | RestResponse | HttpError {
        if (error instanceof HttpError) return error;
        else {
            console.error(error);
            try {
                return new HttpError(`Internal error: ${error}\nSee logs for details`, 500);
            }
            catch {
                return new HttpError('Internal error.\nSee logs for details', 500);
            }
        }
    }

    public async attach(server: Deno.Listener) {
        while (true) {
            for await (const conn of server) {
                (async () => {
                    for await (const req of Deno.serveHttp(conn)) {
                        const r = await this.handle(RestRequest.fromMessage(req));
                        if (r) req.respondWith(r.toFetchResponse());
                    }
                })().catch(console.error);
            }
        }
    }
}