Every 15 minutes, compute contract volume in last 24 hours and 7 days

functions/src/create-contract.ts

@@ -114,6 +114,9 @@ function getNewContract(
 
     createdTime: Date.now(),
     lastUpdatedTime: Date.now(),
+
+    volume24Hours: 0,
+    volume7Days: 0,
   }
 
   if (closeTime) contract.closeTime = closeTime

functions/src/index.ts

@@ -8,3 +8,4 @@ export * from './resolve-market'
 export * from './stripe'
 export * from './sell-bet'
 export * from './create-contract'
+export * from './update-contract-metrics'

functions/src/types/contract.ts

@@ -23,4 +23,7 @@ export type Contract = {
   isResolved: boolean
   resolutionTime?: number // When the contract creator resolved the market
   resolution?: 'YES' | 'NO' | 'CANCEL' // Chosen by creator; must be one of outcomes
+
+  volume24Hours: number
+  volume7Days: number
 }

functions/src/update-contract-metrics.ts

@@ -0,0 +1,40 @@
+import * as functions from 'firebase-functions'
+import * as admin from 'firebase-admin'
+import * as _ from 'lodash'
+import { Contract } from './types/contract'
+import { getValues } from './utils'
+import { Bet } from './types/bet'
+
+const firestore = admin.firestore()
+
+const oneDay = 1000 * 60 * 60 * 24
+
+export const updateContractMetrics = functions.pubsub
+  .schedule('every 15 minutes')
+  .onRun(async () => {
+    const contracts = await getValues<Contract>(
+      firestore.collection('contracts')
+    )
+    await Promise.all(
+      contracts.map(async (contract) => {
+        const volume24Hours = await computeVolumeFrom(contract, oneDay)
+        const volume7Days = await computeVolumeFrom(contract, oneDay * 7)
+
+        const contractRef = firestore.doc(`contracts/${contract.id}`)
+        return contractRef.update({
+          volume24Hours,
+          volume7Days,
+        })
+      })
+    )
+  })
+
+const computeVolumeFrom = async (contract: Contract, timeAgoMs: number) => {
+  const bets = await getValues<Bet>(
+    firestore
+      .collection(`contracts/${contract.id}/bets`)
+      .where('createdTime', '>', Date.now() - timeAgoMs)
+  )
+
+  return _.sumBy(bets, (bet) => Math.abs(bet.amount))
+}

web/lib/firebase/contracts.ts

@@ -42,6 +42,9 @@ export type Contract = {
   isResolved: boolean
   resolutionTime?: number // When the contract creator resolved the market
   resolution?: 'YES' | 'NO' | 'CANCEL' // Chosen by creator; must be one of outcomes
+
+  volume24Hours: number
+  volume7Days: number
 }
 
 export function path(contract: Contract) {