Send out email template for 3 trending markets

common/user.ts

@@ -57,6 +57,7 @@ export type PrivateUser = {
   unsubscribedFromCommentEmails?: boolean
   unsubscribedFromAnswerEmails?: boolean
   unsubscribedFromGenericEmails?: boolean
+  unsubscribedFromWeeklyTrendingEmails?: boolean
   manaBonusEmailSent?: boolean
   initialDeviceToken?: string
   initialIpAddress?: string

functions/src/utils.ts

@@ -88,6 +88,12 @@ export const getPrivateUser = (userId: string) => {
   return getDoc<PrivateUser>('private-users', userId)
 }
 
+export const getAllPrivateUsers = async () => {
+  const firestore = admin.firestore()
+  const users = await firestore.collection('private-users').get()
+  return users.docs.map((doc) => doc.data() as PrivateUser)
+}
+
 export const getUserByUsername = async (username: string) => {
   const firestore = admin.firestore()
   const snap = await firestore

functions/src/weekly-markets-emails.ts

@@ -0,0 +1,93 @@
+import * as functions from 'firebase-functions'
+import * as admin from 'firebase-admin'
+
+import { Contract } from '../../common/contract'
+import { getAllPrivateUsers, getPrivateUser, getValues, log } from './utils'
+import { sendTemplateEmail } from './send-email'
+import { createRNG, shuffle } from '../../common/util/random'
+import { filterDefined } from '../../common/util/array'
+
+export const weeklyMarketsEmails = functions.pubsub
+  .schedule('every 1 minutes')
+  .onRun(async () => {
+    await sendTrendingMarketsEmailsToAllUsers()
+  })
+
+const firestore = admin.firestore()
+
+async function getTrendingContracts() {
+  return await getValues<Contract>(
+    firestore
+      .collection('contracts')
+      .where('isResolved', '==', false)
+      .where('visibility', '==', 'public')
+      .orderBy('popularityScore', 'desc')
+      .limit(50)
+  )
+}
+
+async function sendTrendingMarketsEmailsToAllUsers() {
+  const numMarketsToSend = 3
+  // const privateUsers = await getAllPrivateUsers()
+  // uses dev ian's private user for testing
+  const privateUser = await getPrivateUser('6hHpzvRG0pMq8PNJs7RZj2qlZGn2')
+  const privateUsers = filterDefined([privateUser])
+  // get all users that haven't unsubscribed from weekly emails
+  const privateUsersToSendEmailsTo = privateUsers.filter((user) => {
+    return !user.unsubscribedFromWeeklyTrendingEmails
+  })
+  const trendingContracts = await getTrendingContracts()
+  for (const privateUser of privateUsersToSendEmailsTo) {
+    if (!privateUser.email) {
+      log(`No email for ${privateUser.username}`)
+      continue
+    }
+    const contractsAvailableToSend = trendingContracts.filter((contract) => {
+      return !contract.uniqueBettorIds?.includes(privateUser.id)
+    })
+    if (contractsAvailableToSend.length < numMarketsToSend) {
+      log('not enough new, unbet-on contracts to send to user', privateUser.id)
+      continue
+    }
+    // choose random subset of contracts to send to user
+    const contractsToSend = chooseRandomSubset(
+      contractsAvailableToSend,
+      numMarketsToSend
+    )
+
+    await sendTemplateEmail(
+      privateUser.email,
+      contractsToSend[0].question,
+      '3-trending-markets',
+      {
+        question1title: contractsToSend[0].question,
+        question1Description: getTextDescription(contractsToSend[0]),
+        question1link: contractUrl(contractsToSend[0]),
+        question2title: contractsToSend[1].question,
+        question2Description: getTextDescription(contractsToSend[1]),
+        question2link: contractUrl(contractsToSend[1]),
+        question3title: contractsToSend[2].question,
+        question3Description: getTextDescription(contractsToSend[2]),
+        question3link: contractUrl(contractsToSend[2]),
+      }
+    )
+  }
+}
+
+function getTextDescription(contract: Contract) {
+  // if the contract.description is of type string, return it, otherwise return the text of the json content
+  return typeof contract.description === 'string'
+    ? contract.description
+    : contract.description.text ?? ''
+}
+
+function contractUrl(contract: Contract) {
+  return `https://manifold.markets/${contract.creatorUsername}/${contract.slug}`
+}
+
+function chooseRandomSubset(contracts: Contract[], count: number) {
+  const fiveMinutes = 5 * 60 * 1000
+  const seed = Math.round(Date.now() / fiveMinutes).toString()
+  shuffle(contracts, createRNG(seed))
+  return contracts.slice(0, count)
+}