hostbbq-monitoring/fcm/express/src/index.ts

import axios, { AxiosResponse, AxiosError } from 'axios';
import dotenv from 'dotenv';
import express, { NextFunction, Request, Response } from 'express';
import firebaseAdmin from 'firebase-admin';
import fsp from 'fs/promises';
import path from 'path';

dotenv.config();

const STATIC_WEB_DIR = 'public';

(async () => {
  try {
    const gcmSettings = JSON.parse(
      await fsp.readFile(process.env.GOOGLE_GLOUD_MESSAGING_CREDENTIALS ?? 'google-cloud/gcm-api.json', { encoding: 'utf-8' })
    );

    const server = express();
    const firebase = firebaseAdmin.initializeApp();

    server.get('/topics/:regToken', async (req, res, next) => {
      try {
        const regToken = req.params.regToken;
        const { apiToken } = gcmSettings;
        const response = await axios.get<any, AxiosResponse<any>>(`https://iid.googleapis.com/iid/info/${regToken}?details=true`, {
          headers: {
            Authorization: `key=${apiToken}`
          }
        });
        res.send(response.data);
      } catch (err) {
        next(err);
      }
    });

    server.put('/topics/:topic/:regToken', async (req, res, next) => {
      try {
        const topic = req.params.topic;
        const regToken = req.params.regToken;

        const response = await firebase.messaging().subscribeToTopic(regToken, topic);
        if (!response.failureCount) return res.send({ ok: true });

        throw response.errors;
      } catch (err) {
        next(err);
      }
    });

    server.delete('/topics/:topic/:regToken', async (req, res, next) => {
      try {
        const topic = req.params.topic;
        const regToken = req.params.regToken;

        const response = await firebase.messaging().unsubscribeFromTopic(regToken, topic);
        if (!response.failureCount) return res.send({ ok: true });

        throw response.errors;
      } catch (err) {
        next(err);
      }
    });

    server.get('/logo.png', async (req, res, next) => {
      try {
        const files = await fsp.readdir(STATIC_WEB_DIR, { encoding: 'utf-8' });
        const logo = files.find(file => file.includes('logo') && file.endsWith('.png'));

        if (!logo) {
          throw { type: 'http', message: 'File not found', status: 404 };
        }

        res.sendFile(path.resolve(STATIC_WEB_DIR, logo));
      } catch (err) {
        next(err);
      }
    });

    server.use('/', express.static(STATIC_WEB_DIR));

    server.use('**', express.static(path.join(STATIC_WEB_DIR, 'index.html')));

    server.use((err: any, req: Request, res: Response, next: NextFunction) => {
      let log = false;

      if (err instanceof AxiosError) {
        log = true;
        res.status(err.status ?? err.response?.status ?? 500).send(err.message);
      } else {
        const keys = Object.keys(err);

        if (keys.includes('type') && err.type === 'http') {
          res.status(err.status).send(err.message);
        } else {
          log = true;
          res.status(500).send(JSON.stringify(err));
        }
      }

      if (log) console.error('[ERROR] Webservice ErrorHandler caught:', err);
    });

    const port = Number(process.env.WEB_PORT ?? '80');
    server.listen(port, () => console.log('[FCM BACKEND] Webserver running at', `http://localhost:${port}`));
  } catch (err) {
    console.error(err);
    process.exit(1);
  }
})();