app.ts

import * as BodyParser from 'body-parser';
import * as Express from 'express';
import UserController from './controllers/user-controller';
import ErrorMiddleware from './middlewares/base/errormiddleware';
import Controller from './types/controller';

class App {

    public app: Express.Application;

    public constructor(controllers: Controller[]) {
        this.app = Express();
        this.initializeBaseConfig();
        this.initializeControllers(controllers);
        this.initializeMiddleWares();
    }

    /**
     * Application config
     */
    private initializeBaseConfig(): void {
        // Allow any method from any host and log requests
        this.app.use((req: Express.Request, res: Express.Response, next: Express.NextFunction) => {
            const corsWhitelist = [
                'abc.com',
                'def.com',
                'localhost:4200',
                'abc.in'
            ];
            for (let i = 0; i < corsWhitelist.length; i++) {
                if (req.headers.origin.indexOf(corsWhitelist[i]) >= 0) {
                    res.header('Access-Control-Allow-Origin', req.headers.origin);
                    break;
                }                
            }
            // res.header('Access-Control-Allow-Origin', '*');
            res.header('Access-Control-Allow-Headers', 'Origin, X-Requested-With, Content-Type, Accept');
            res.header('Access-Control-Allow-Methods', 'OPTIONS, GET, POST, PUT, DELETE, PATCH');
            if ('OPTIONS' === req.method) {
                res.sendStatus(200);
            } else {
                console.log(`${req.ip} ${req.method} ${req.url}`);
                next();
            }
        });

        // support application/json type post data
        this.app.use(BodyParser.json());

        // support application/x-www-form-urlencoded post data
        this.app.use(BodyParser.urlencoded({ extended: false })); 
    }

    /**
     * Initializes different middlewares.
     */
    private initializeMiddleWares() {        
        this.app.use(ErrorMiddleware);        
    }

    /**
     * Initializes the controllers.
     * @param controllers 
     */
    public initializeControllers(controllers: Controller[]): void {    
        controllers.forEach((controller: Controller) => {
            this.app.use('/', controller.router);
        });
    }
}

export default new App([
    new UserController()
]).app;