index.ts

import { default as axios, default as Axios } from "axios";
import express from "express";
import objectHash from "object-hash";
import puppeteer from "puppeteer-extra";
import StealthPlugin from "puppeteer-extra-plugin-stealth";
import { Browser } from "puppeteer-extra/dist/puppeteer";
import getConfig, { getUrls, getZipFromUrl } from "./config";

class Impfbot {
  private config = getConfig();
  private browser?: Browser;
  private errorCount: number = 0;
  private lastHash: Record<string, string> = {};
  private lastAppointmentsAvailable: Record<string, number> = {};
  private queue: string[] = getUrls();

  public boot = async () => {
    console.log("Booting 116117bot");

    const app = express();
    app.get("/", (req, res) => res.send());
    app.listen(this.config.port);

    await this.startBrowser();
    this.alertPushover(`Now monitoring ${this.queue.length} URL(s).`, -2);
    this.runLoopStep();
  };

  private startBrowser = async () => {
    this.browser?.close();
    puppeteer.use(StealthPlugin());
    const defaultArgs = ["--window-size=1600,1200"];
    this.browser = await puppeteer.launch({
      executablePath: this.config.chromiumExecutablePath,
      headless: this.config.headless,
      defaultViewport: null,
      args: [
        ...defaultArgs,
        ...(this.config.noPuppeteerSandbox
          ? ["--no-sandbox", "--disable-setuid-sandbox"]
          : []),
      ],
    });
  };

  private limboLoop = () => {
    console.error("Caught in limbo loop, as fatal error was discovered.");
    setTimeout(this.limboLoop, 1000 * 60 * 60);
  };

  private runLoopStep = async () => {
    const url = this.queue.shift();
    try {
      if (!url) throw "No URL in queue.";
      const [
        appointmentsAvailable,
        htmlHash,
        html,
      ] = await this.findAppointmentsInUrl(url);
      this.announceNewResults(htmlHash, url, appointmentsAvailable, html);
      this.lastHash[url] = htmlHash;
      this.lastAppointmentsAvailable[url] = appointmentsAvailable;
      setTimeout(this.runLoopStep, this.nextTimeout * 1000);
      this.errorCount = 0;
    } catch (e) {
      this.errorCount++;
      console.error(e);
      this.startBrowser();
      if (this.errorCount < 10) {
        console.error(`Error ${this.errorCount}, delaying next request.`);
        setTimeout(this.runLoopStep, this.config.timeout.error * 1000);
      } else {
        console.error("Too many errors, bailing out.");
        this.alertPushover("Too many errors, bailing out.", 0);
        this.limboLoop();
      }
    } finally {
      if (url) this.queue.push(url);
    }
  };

  private findAppointmentsInUrl = async (
    url: string
  ): Promise<[number, string, string]> => {
    if (url.indexOf("impftermine/service") !== -1) {
      // the entered URL is a pre-code URL (finding appointments before having a booking code)
      const zip = getZipFromUrl(url);
      const vaccinations = (
        await axios.get(
          "https://001-iz.impfterminservice.de/assets/static/its/vaccination-list.json"
        )
      ).data
        .map((v: any) => v.qualification)
        .join(",");
      const checkUrl =
        url.substr(0, 36) +
        "rest/suche/termincheck?plz=" +
        zip +
        "&leistungsmerkmale=" +
        vaccinations +
        "&cachebuster=" +
        Date.now();
      const availableResponse = (await axios.get(checkUrl)).data;
      return [
        availableResponse["termineVorhanden"] ? 1 : 0,
        objectHash(availableResponse),
        JSON.stringify(availableResponse),
      ];
    } else if (url.indexOf("impftermine/suche") !== -1) {
      // the entered URL is an post-code URL (finding appointment after having a booking code)
      console.warn(
        "It is not recommended to monitor this kind of URL, as it immediately results in appointment reservations, reducing the number of appointments available to the public. Please see Readme."
      );
      const page = await this.browser!.defaultBrowserContext().newPage();
      // We intercept requests to a specific URL that would sometimes result in a 429
      await page.setRequestInterception(true);
      page.on("request", (request) => {
        if (request.url().indexOf("terminpaare") !== -1) {
        }
        if (request.url().indexOf("buchung") !== -1) {
          request.respond({ status: 404, body: "{}" });
        } else request.continue();
      });
      //
      await page.goto(url);
      const terminSuchenButtonSelector =
        ".its-search-step-content .btn-magenta";
      try {
        await page.waitForSelector(terminSuchenButtonSelector, {
          timeout: 2 * 60 * 1000,
        });
      } catch (e) {
        throw "Termin suchen button not found, likely error 429.";
      }
      const terminSuchenButton = await page.$(terminSuchenButtonSelector);
      await terminSuchenButton?.click();
      await page.waitForResponse(
        (res) => res.url().indexOf("terminpaare") !== -1,
        { timeout: 10 * 1000 }
      );
      const appointmentsAvailable =
        (await page.$$(".its-slot-pair-search-radio-wrapper")).length - 1;
      const html = await page.content();
      await page.close();
      return [
        appointmentsAvailable,
        objectHash(html.split("<body").slice(-1)),
        html,
      ];
    } else {
      throw "The URL type could not be identified.";
    }
  };

  private alertPushover = async (message: string, priority: number) => {
    if (this.config.pushover.token && this.config.pushover.user) {
      try {
        Axios.post("https://api.pushover.net/1/messages.json", {
          token: this.config.pushover.token,
          user: this.config.pushover.user,
          message,
          priority,
        });
      } catch (error) {
        console.error("Error when pushing to pushover, will retry.");
        console.error(error);
        setTimeout(() => this.alertPushover(message, priority), 10000);
      }
    }
  };

  private announceNewResults = (
    hash: string,
    url: string,
    appointmentsAvailable: number,
    html: string
  ) => {
    const hashChanged = this.lastHash[url] !== hash;
    console.info(
      "📅",
      new Date(),
      "  🌍",
      getZipFromUrl(url),
      hashChanged ? "  🔵" : "  ⚪️",
      hash.substr(0, 8),
      appointmentsAvailable > 0 ? "  ✳️" : "  ⛔️",
      `${appointmentsAvailable} appointment(s) available`
    );
    if (hashChanged) {
      if (this.config.logHtml) {
        console.log("---------------------------");
        console.log(html.replace(/(\r\n|\n|\r)/gm, ""));
        console.log("---------------------------");
      }
      if (
        (this.lastAppointmentsAvailable[url] ?? 0) === 0 &&
        appointmentsAvailable > 0
      ) {
        this.alertPushover(
          `There are ${appointmentsAvailable} available appointment(s) for ${getZipFromUrl(
            url
          )}!`,
          1
        );
      }
      if (
        (this.lastAppointmentsAvailable[url] ?? 0) > 0 &&
        appointmentsAvailable === 0
      ) {
        this.alertPushover(
          `There are no more available appointments for ${getZipFromUrl(url)}.`,
          -1
        );
      }
    }
  };

  private get nextTimeout(): number {
    let timeout: number = this.config.timeout.regular;
    return timeout;
  }
}

function awaitTimeout(ms: number) {
  return new Promise((resolve) => setTimeout(resolve, ms));
}

const impfbot = new Impfbot();
impfbot.boot();