Firebase forum system functions.

Firebase_Forum_Functions.ts

// ABOUT: These are functions for a Firebase forum system.
// You need NodeJS (nodejs.org) installed on your dev PC and create an Algolia and firebase project.

// Create an empty folder.
// Open terminal/cmd, navigate to the new folder and type in (NOTE: Use TypeScript):
// npm install -g firebase-tools
// firebase login
// firebase init
// npm install algoliasearch --save
// firebase functions:config:set algolia.appid="YOUR_APP_ID" algolia.apikey="YOUR_API_KEY"
// Open 'functions/src/index.ts' with a text editor like NotePad and put this code in it.
// After, in terminal/cmd type in 'firebase deploy' to make it go live. (This process can be kinda slow at times.)

import * as functions from 'firebase-functions';
import * as admin from 'firebase-admin';
import algoliasearch from 'algoliasearch';

// CONFIGURATION
const algoliaIndex = "ALGOLIA_INDEX_NAME_HERE";
// END

admin.initializeApp();
const db = admin.firestore();
const algoliaClient = algoliasearch(functions.config().algolia.appid, functions.config().algolia.apikey);
const collectionIndex = algoliaClient.initIndex(algoliaIndex);

// HTTP request, show list of all users
export const getUserList = functions.https.onRequest(async (req, res) => {
  res.set('Access-Control-Allow-Origin', '*');
  res.set('Access-Control-Allow-Methods', 'GET');
  res.set('Access-Control-Allow-Headers', '*');
    const listAllUsers = (nextPageToken?: any) => { // List batch of users, 1000 at a time.
      admin
        .auth()
        .listUsers(1000, nextPageToken)
        .then((listUsersResult) => {
          // our JSON structure
          type User = {
            displayName: string | undefined;
            photoURL: string | undefined;
          };
          let TheRecord: { [uid: string]: User } = {};
          // iterate through users from server
          listUsersResult.users.forEach((userRecord) => {
            // build JSON data with key UID.
            TheRecord[userRecord.uid] = {
              displayName: userRecord.displayName,
              photoURL: userRecord.photoURL,
            };
          });
          if (listUsersResult.pageToken) { // List next batch of users.
            res.status(200).send(listAllUsers(listUsersResult.pageToken));
          } else {
            res.send(TheRecord);
          }
        })
        .catch((error) => {
          console.log('Error listing users:', error);
        });
    };
    listAllUsers();
});

// Send post data to Firestore (new post and replies)
export const newPost = functions.https.onRequest(async (req, res) => {
  res.set('Access-Control-Allow-Origin', '*');
  res.set('Access-Control-Allow-Methods', 'POST');
  res.set('Access-Control-Allow-Headers', '*');
  var DBCollection = "topics";
  if (req.method === 'POST') {
    var data = {
      category: req.body.category,
      content: req.body.content,
      title: req.body.title,
      user_id: req.body.accid,
      created: Number(Date.now().toString())
    };
    if (req.body.type === "reply")
      DBCollection = "replies";
    db.collection(DBCollection).add(data)
    .then(function(docRef) {
      res.setHeader('Content-Type', 'application/json');
      res.status(200).json({message: "success", id: docRef.id});
    });
  }
});

// Automatic request on new docs in firestore to update Algolia indices
export const algoliaTopicsSync = functions.firestore.document('topics/{docId}').onWrite((change, _context) => {
  const oldData = change.before;
  const newData = change.after;
  const data = newData.data();
  const objectID = newData.id;
  if (!oldData.exists && newData.exists) { // creating
      return collectionIndex.saveObject(Object.assign({}, { objectID }, data));
  } else if (!newData.exists && oldData.exists) { // deleting
      return collectionIndex.deleteObject(objectID);
  } else  { // updating
      return collectionIndex.saveObject(Object.assign({}, { objectID }, data));
  }
})