Resolve "Create a users endpoint"

Closes #6 (closed)

backend/src/index.ts

 import express from 'express';
+import path from 'path';
 
 const app = express();
 const port = 3000;
 
+// const cors = require('cors');
+// app.use(cors());
+
+// in testing, we don't want to cache the results
+app.set('etag', false);
+app.use((req, res, next) => {
+  res.setHeader('Cache-Control', 'no-store');
+  next();
+});
+
 app.get('/', (req, res) => {
   res.send('Hello, World!');
 });
@@ -10,3 +21,67 @@ app.get('/', (req, res) => {
 app.listen(port, () => {
   console.log(`Server started on port ${port}`);
 });
+
+// establish connection to firebase
+const admin = require('firebase-admin');
+const serviceAccount = path.join(__dirname, '../..', 'keys', 'fb-key.json');
+
+admin.initializeApp({
+  credential: admin.credential.cert(serviceAccount),
+});
+
+// returns all the user-id's
+app.get('/user', async (req, res) => {
+  const usersRef = admin.firestore().collection('users');
+  const querySnapshot = await usersRef.get();
+
+  if (querySnapshot.empty) {
+    res.status(204).send('No users found');
+  } else {
+    const userids = querySnapshot.docs.map((doc: { id: any }) => doc.id);
+    res.status(200).send(userids);
+  }
+});
+
+// returns data of a specific user
+app.get('/user/:idOrUsername', async (req, res) => {
+  const usersRef = admin.firestore().collection('users');
+  const snapshot = await usersRef.get();
+  const searchParam = req.params.idOrUsername;
+
+  const user =
+    snapshot.docs.find((doc: { id: string }) => doc.id === searchParam) ||
+    (
+      await Promise.all(
+        snapshot.docs.map(async (doc: { id: string }) => {
+          const userSnapshot = await usersRef.doc(doc.id).get();
+          return userSnapshot.data().username === searchParam ? userSnapshot : null;
+        })
+      )
+    ).find(Boolean);
+
+  if (user) {
+    res.status(200).send(user.data());
+  } else {
+    res.status(404).send('User not found');
+  }
+});
+
+// create new user
+app.post('/user/create/:username', async (req, res) => {
+  const usersRef = admin.firestore().collection('users');
+  const querySnapshot = await usersRef.where('username', '==', req.params.username).get();
+
+  if (!querySnapshot.empty) {
+    res.status(409).send('User already exists');
+  } else {
+    const newUserRef = await usersRef.add({
+      username: req.params.username,
+      highscore: 0,
+      games: 0,
+      wins: 0,
+      losses: 0,
+    });
+    res.status(201).send(newUserRef.id);
+  }
+});