swaf/src/components/ExpressAppComponent.ts

import ApplicationComponent from "../ApplicationComponent";
import express, {Express, NextFunction, Request, Response, Router} from "express";
import Logger from "../Logger";
import {Server} from "http";
import {MulterError} from "multer";
import {FileError, ValidationBag} from "../db/Validator";

export default class ExpressAppComponent extends ApplicationComponent<void> {
    private readonly port: number;
    private server?: Server;

    constructor(port: number) {
        super();
        this.port = port;
    }

    public async start(app: Express, router: Router): Promise<void> {
        this.server = app.listen(this.port, 'localhost', () => {
            Logger.info(`Web server running on localhost:${this.port}.`);
        });

        this.app?.setupRequestParsingMiddlewares(router);

        // Multer error handler
        router.use((err: any, req: Request, res: Response, next: NextFunction) => {
            if (err instanceof MulterError) {
                const bag = new ValidationBag();
                const validationError = new FileError(err.message);
                validationError.thingName = err.field;
                bag.addMessage(validationError);
                req.flash('validation', bag.getMessages());
                res.redirectBack();
            } else {
                next(err);
            }
        });

        router.use(express.json());
        router.use(express.urlencoded({
            extended: true,
        }));

        router.use((req, res, next) => {
            req.models = {};
            req.modelCollections = {};
            next();
        });
    }

    public async stop(): Promise<void> {
        if (this.server) {
            await this.close('Webserver', this.server, this.server.close);
        }
    }

    public getServer(): Server {
        if (!this.server) throw 'Server was not initialized.';
        return this.server;
    }
}