swaf/src/components/PreviousUrlComponent.ts

import {Router} from "express";
import onFinished from "on-finished";

import ApplicationComponent from "../ApplicationComponent.js";
import {logger} from "../Logger.js";
import SessionComponent from "./SessionComponent.js";

export default class PreviousUrlComponent extends ApplicationComponent {
    public async handleRoutes(router: Router): Promise<void> {
        router.use((req, res, next) => {
            req.getPreviousUrl = () => {
                let url = req.header('referer');
                if (url) {
                    if (url.indexOf('://') >= 0) url = '/' + url.split('/').slice(3).join('/');
                    if (url !== req.originalUrl) return url;
                }

                if (this.getApp().asOptional(SessionComponent)) {
                    const session = req.getSessionOptional();
                    url = session?.previousUrl;
                    if (url && url !== req.originalUrl) return url;
                }

                return null;
            };
            res.setLazyLocal('previousUrl', () => req.getPreviousUrl());

            req.getIntendedUrl = () => {
                return req.query.redirect_uri?.toString() || null;
            };

            if (this.getApp().asOptional(SessionComponent)) {
                const session = req.getSessionOptional();
                if (session && req.method === 'GET') {
                    onFinished(res, (err) => {
                        if (err) return;

                        const contentType = res.getHeader('content-type');
                        if (res.statusCode === 200 &&
                            contentType && typeof contentType !== 'number' && contentType.indexOf('text/html') >= 0) {
                            session.previousUrl = req.originalUrl;

                            session.save((err) => {
                                if (err) logger.error(err, 'Error while saving session');
                                else logger.debug('Prev url set to', session.previousUrl);
                            });
                        }
                    });
                }
            }
            next();
        });
    }
}