Sell bet loan: negate buy bet's loan

common/loans.ts

@@ -1,9 +1,21 @@
 import { Dictionary, groupBy, sumBy, minBy } from 'lodash'
 import { Bet } from './bet'
 import { getContractBetMetrics } from './calculate'
-import { Contract, CPMMContract, FreeResponseContract, MultipleChoiceContract } from './contract'
+import {
+  Contract,
+  CPMMContract,
+  FreeResponseContract,
+  MultipleChoiceContract,
+} from './contract'
 import { filterDefined } from './util/array'
 
+const LOAN_WEEKLY_RATE = 0.05
+
+const calculateNewLoan = (investedValue: number, loanTotal: number) => {
+  const netValue = investedValue - loanTotal
+  return netValue * LOAN_WEEKLY_RATE
+}
+
 export const getUserLoanUpdates = (
   bets: Bet[],
   contractsById: Dictionary<Contract>
@@ -80,10 +92,3 @@ const getFreeResponseContractLoanUpdate = (
     }
   })
 }
-
-const LOAN_WEEKLY_RATE = 0.05
-
-const calculateNewLoan = (investedValue: number, loanTotal: number) => {
-  const netValue = investedValue - loanTotal
-  return netValue * LOAN_WEEKLY_RATE
-}

common/sell-bet.ts

@@ -13,7 +13,7 @@ export type CandidateBet<T extends Bet> = Omit<T, 'id' | 'userId'>
 
 export const getSellBetInfo = (bet: Bet, contract: DPMContract) => {
   const { pool, totalShares, totalBets } = contract
-  const { id: betId, amount, shares, outcome } = bet
+  const { id: betId, amount, shares, outcome, loanAmount } = bet
 
   const adjShareValue = calculateDpmShareValue(contract, bet)
 
@@ -64,6 +64,7 @@ export const getSellBetInfo = (bet: Bet, contract: DPMContract) => {
       betId,
     },
     fees,
+    loanAmount: -(loanAmount ?? 0),
   }
 
   return {

functions/src/sell-bet.ts

@@ -50,11 +50,12 @@ export const sellbet = newEndpoint({}, async (req, auth) => {
 
     /* eslint-disable-next-line @typescript-eslint/no-non-null-assertion */
     const saleAmount = newBet.sale!.amount
-    const newBalance = user.balance + saleAmount - (bet.loanAmount ?? 0)
+    const newBalance = user.balance + saleAmount + (newBet.loanAmount ?? 0)
     const newBetDoc = firestore.collection(`contracts/${contractId}/bets`).doc()
 
     transaction.update(userDoc, { balance: newBalance })
     transaction.update(betDoc, { isSold: true })
+    // Note: id should have been newBetDoc.id! But leaving it for now so it's consistent.
     transaction.create(newBetDoc, { id: betDoc.id, userId: user.id, ...newBet })
     transaction.update(
       contractDoc,