Clean some API stuff up and instrument placeBet with a bunch of logging (#521)

* Hoist some variables out of functions

* Use built in CORS processing machinery

* Instrument `placebet` with a bunch of logging

functions/package.json

@@ -21,7 +21,6 @@
   "main": "lib/functions/src/index.js",
   "dependencies": {
     "@amplitude/node": "1.10.0",
-    "cors": "2.8.5",
     "fetch": "1.1.0",
     "firebase-admin": "10.0.0",
     "firebase-functions": "3.21.2",

functions/src/api.ts

@@ -1,9 +1,7 @@
 import * as admin from 'firebase-admin'
-import { Response } from 'express'
 import { logger } from 'firebase-functions/v2'
-import { onRequest, Request } from 'firebase-functions/v2/https'
-
-import * as Cors from 'cors'
+import { HttpsOptions, onRequest, Request } from 'firebase-functions/v2/https'
+import { log } from './utils'
 import { z } from 'zod'
 
 import { PrivateUser } from '../../common/user'
@@ -33,6 +31,12 @@ export class APIError {
   }
 }
 
+const auth = admin.auth()
+const firestore = admin.firestore()
+const privateUsers = firestore.collection(
+  'private-users'
+) as admin.firestore.CollectionReference<PrivateUser>
+
 export const parseCredentials = async (req: Request): Promise<Credentials> => {
   const authHeader = req.get('Authorization')
   if (!authHeader) {
@@ -47,8 +51,7 @@ export const parseCredentials = async (req: Request): Promise<Credentials> => {
   switch (scheme) {
     case 'Bearer':
       try {
-        const jwt = await admin.auth().verifyIdToken(payload)
-        return { kind: 'jwt', data: jwt }
+        return { kind: 'jwt', data: await auth.verifyIdToken(payload) }
       } catch (err) {
         // This is somewhat suspicious, so get it into the firebase console
         logger.error('Error verifying Firebase JWT: ', err)
@@ -62,8 +65,6 @@ export const parseCredentials = async (req: Request): Promise<Credentials> => {
 }
 
 export const lookupUser = async (creds: Credentials): Promise<AuthedUser> => {
-  const firestore = admin.firestore()
-  const privateUsers = firestore.collection('private-users')
   switch (creds.kind) {
     case 'jwt': {
       if (typeof creds.data.user_id !== 'string') {
@@ -77,8 +78,7 @@ export const lookupUser = async (creds: Credentials): Promise<AuthedUser> => {
       if (privateUserQ.empty) {
         throw new APIError(403, `No private user exists with API key ${key}.`)
       }
-      const privateUserSnap = privateUserQ.docs[0]
-      const privateUser = privateUserSnap.data() as PrivateUser
+      const privateUser = privateUserQ.docs[0].data()
       return { uid: privateUser.id, creds: { privateUser, ...creds } }
     }
     default:
@@ -86,21 +86,6 @@ export const lookupUser = async (creds: Credentials): Promise<AuthedUser> => {
   }
 }
 
-export const applyCors = (
-  req: Request,
-  res: Response,
-  params: Cors.CorsOptions
-) => {
-  return new Promise((resolve, reject) => {
-    Cors(params)(req, res, (result) => {
-      if (result instanceof Error) {
-        return reject(result)
-      }
-      return resolve(result)
-    })
-  })
-}
-
 export const zTimestamp = () => {
   return z.preprocess((arg) => {
     return typeof arg == 'number' ? new Date(arg) : undefined
@@ -122,18 +107,21 @@ export const validate = <T extends z.ZodTypeAny>(schema: T, val: unknown) => {
   }
 }
 
+const DEFAULT_OPTS: HttpsOptions = {
+  minInstances: 1,
+  cors: [CORS_ORIGIN_MANIFOLD, CORS_ORIGIN_LOCALHOST],
+}
+
 export const newEndpoint = (methods: [string], fn: Handler) =>
-  onRequest({ minInstances: 1 }, async (req, res) => {
+  onRequest(DEFAULT_OPTS, async (req, res) => {
+    log('Request processing started.')
     try {
-      await applyCors(req, res, {
-        origin: [CORS_ORIGIN_MANIFOLD, CORS_ORIGIN_LOCALHOST],
-        methods: methods,
-      })
       if (!methods.includes(req.method)) {
         const allowed = methods.join(', ')
         throw new APIError(405, `This endpoint supports only ${allowed}.`)
       }
       const authedUser = await lookupUser(await parseCredentials(req))
+      log('User credentials processed.')
       res.status(200).json(await fn(req, authedUser))
     } catch (e) {
       if (e instanceof APIError) {

functions/src/place-bet.ts

@@ -13,6 +13,7 @@ import {
 } from '../../common/new-bet'
 import { addObjects, removeUndefinedProps } from '../../common/util/object'
 import { redeemShares } from './redeem-shares'
+import { log } from './utils'
 
 const bodySchema = z.object({
   contractId: z.string(),
@@ -33,9 +34,11 @@ const numericSchema = z.object({
 })
 
 export const placebet = newEndpoint(['POST'], async (req, auth) => {
+  log('Inside endpoint handler.')
   const { amount, contractId } = validate(bodySchema, req.body)
 
   const result = await firestore.runTransaction(async (trans) => {
+    log('Inside main transaction.')
     const contractDoc = firestore.doc(`contracts/${contractId}`)
     const userDoc = firestore.doc(`users/${auth.uid}`)
     const [contractSnap, userSnap] = await Promise.all([
@@ -44,6 +47,7 @@ export const placebet = newEndpoint(['POST'], async (req, auth) => {
     ])
     if (!contractSnap.exists) throw new APIError(400, 'Contract not found.')
     if (!userSnap.exists) throw new APIError(400, 'User not found.')
+    log('Loaded user and contract snapshots.')
 
     const contract = contractSnap.data() as Contract
     const user = userSnap.data() as User
@@ -82,6 +86,7 @@ export const placebet = newEndpoint(['POST'], async (req, auth) => {
         throw new APIError(500, 'Contract has invalid type/mechanism.')
       }
     })()
+    log('Calculated new bet information.')
 
     if (
       mechanism == 'cpmm-1' &&
@@ -95,7 +100,9 @@ export const placebet = newEndpoint(['POST'], async (req, auth) => {
     const newBalance = user.balance - amount - loanAmount
     const betDoc = contractDoc.collection('bets').doc()
     trans.create(betDoc, { id: betDoc.id, userId: user.id, ...newBet })
+    log('Created new bet document.')
     trans.update(userDoc, { balance: newBalance })
+    log('Updated user balance.')
     trans.update(
       contractDoc,
       removeUndefinedProps({
@@ -108,11 +115,14 @@ export const placebet = newEndpoint(['POST'], async (req, auth) => {
         volume: volume + amount,
       })
     )
+    log('Updated contract properties.')
 
     return { betId: betDoc.id }
   })
 
+  log('Main transaction finished.')
   await redeemShares(auth.uid, contractId)
+  log('Share redemption transaction finished.')
   return result
 })