server.ts

import express, { Express } from 'express';
import http from "http";
import validUrl from "valid-url";
import { Loader } from './loader';
import { logger, debugLog } from './logging';
import { Pool } from './pool';
import { CacheHTML } from './cache';
import { Request, Response } from 'express-serve-static-core';

export class Server {
    app: Express;
    server: http.Server;
    loader: Loader;
    constructor(port: number, pool: Pool, cache: CacheHTML, timeout: number) {
        this.app = express();
        this.loader = new Loader(pool, cache, timeout);
        this.app.get('/', async (req, res, _) => {
            this.getRootHandler(req, res)
        });
        this.app.get('/healthcheck', async (req, res, _) => {
            this.getHealthcheckHandler(req, res)
        });
        this.server = this.app.listen(
            port,
            () => logger.info("server listening on port " + port),
        );
    }
    async getRootHandler(req: Request, res: Response) {
        logger.info("received HTTP GET: " + req.url);
        let url: string;
        try {
            url = Server.verifyURL(req.query["url"])
        } catch (e) {
            return res.status(403).send({
                "error": String(e)
            });
        }
        const wait = req.query["wait"];
        try {
            const html = await this.loader.spitHTML(url, wait);
            return res.status(200).send({
                "html": html
            });
        } catch (e) {
            logger.error(String(e));
            return res.status(403).send({
                "error": String(e)
            });
        }
    }
    async getHealthcheckHandler(req: Request, res: Response) {
        debugLog.server("received GET /healthcheck request: " + req.url);
        const healthy = true; // TODO
        if (healthy) {
            return res.status(200);
        }
        logger.warn("unhealthy");
        return res.status(500).send("unhealthy");
    }
    static verifyURL(url: string | undefined): string {
        if (url === undefined || url === "") {
            throw new Error("url parameter not provided")
        } else if (validUrl.isWebUri(url) === undefined) {
            throw new Error("url parameter is not a valid URL")
        }
        return url;
    }
    close(callback?: () => void) {
        this.server.close(callback);
    }
}