Put very general share redemption code into common

common/new-bet.ts

@@ -20,9 +20,9 @@ import { noFees } from './fees'
 import { addObjects } from './util/object'
 import { NUMERIC_FIXED_VAR } from './numeric-constants'
 
-export type CandidateBet<T extends Bet> = Omit<T, 'id' | 'userId'>
+export type CandidateBet<T extends Bet = Bet> = Omit<T, 'id' | 'userId'>
 export type BetInfo = {
-  newBet: CandidateBet<Bet>
+  newBet: CandidateBet
   newPool?: { [outcome: string]: number }
   newTotalShares?: { [outcome: string]: number }
   newTotalBets?: { [outcome: string]: number }
@@ -46,7 +46,7 @@ export const getNewBinaryCpmmBetInfo = (
   const probBefore = getCpmmProbability(pool, p)
   const probAfter = getCpmmProbability(newPool, newP)
 
-  const newBet: CandidateBet<Bet> = {
+  const newBet: CandidateBet = {
     contractId: contract.id,
     amount,
     shares,
@@ -96,7 +96,7 @@ export const getNewBinaryDpmBetInfo = (
   const probBefore = getDpmProbability(contract.totalShares)
   const probAfter = getDpmProbability(newTotalShares)
 
-  const newBet: CandidateBet<Bet> = {
+  const newBet: CandidateBet = {
     contractId: contract.id,
     amount,
     loanAmount,
@@ -133,7 +133,7 @@ export const getNewMultiBetInfo = (
   const probBefore = getDpmOutcomeProbability(totalShares, outcome)
   const probAfter = getDpmOutcomeProbability(newTotalShares, outcome)
 
-  const newBet: CandidateBet<Bet> = {
+  const newBet: CandidateBet = {
     contractId: contract.id,
     amount,
     loanAmount,

common/redeem.ts

@@ -0,0 +1,54 @@
+import { partition, sumBy } from 'lodash'
+
+import { Bet } from './bet'
+import { getProbability } from './calculate'
+import { CPMMContract } from './contract'
+import { noFees } from './fees'
+import { CandidateBet } from './new-bet'
+
+type RedeemableBet = Pick<Bet, 'outcome' | 'shares' | 'loanAmount'>
+
+export const getRedeemableAmount = (bets: RedeemableBet[]) => {
+  const [yesBets, noBets] = partition(bets, (b) => b.outcome === 'YES')
+  const yesShares = sumBy(yesBets, (b) => b.shares)
+  const noShares = sumBy(noBets, (b) => b.shares)
+  const shares = Math.max(Math.min(yesShares, noShares), 0)
+  const loanAmount = sumBy(bets, (bet) => bet.loanAmount ?? 0)
+  const loanPayment = Math.min(loanAmount, shares)
+  const netAmount = shares - loanPayment
+  return { shares, loanPayment, netAmount }
+}
+
+export const getRedemptionBets = (
+  shares: number,
+  loanPayment: number,
+  contract: CPMMContract
+) => {
+  const p = getProbability(contract)
+  const createdTime = Date.now()
+  const yesBet: CandidateBet = {
+    contractId: contract.id,
+    amount: p * -shares,
+    shares: -shares,
+    loanAmount: loanPayment ? -loanPayment / 2 : 0,
+    outcome: 'YES',
+    probBefore: p,
+    probAfter: p,
+    createdTime,
+    isRedemption: true,
+    fees: noFees,
+  }
+  const noBet: CandidateBet = {
+    contractId: contract.id,
+    amount: (1 - p) * -shares,
+    shares: -shares,
+    loanAmount: loanPayment ? -loanPayment / 2 : 0,
+    outcome: 'NO',
+    probBefore: p,
+    probAfter: p,
+    createdTime,
+    isRedemption: true,
+    fees: noFees,
+  }
+  return [yesBet, noBet]
+}

functions/src/redeem-shares.ts

@@ -1,61 +1,11 @@
 import * as admin from 'firebase-admin'
-import { partition, sumBy } from 'lodash'
 
 import { Bet } from '../../common/bet'
-import { getProbability } from '../../common/calculate'
+import { getRedeemableAmount, getRedemptionBets } from '../../common/redeem'
 
-import { Contract, CPMMContract } from '../../common/contract'
+import { Contract } from '../../common/contract'
-import { noFees } from '../../common/fees'
 import { User } from '../../common/user'
 
-type CandidateBet<T extends Bet> = Omit<T, 'id' | 'userId'>
-type RedeemableBet = Pick<Bet, 'outcome' | 'shares' | 'loanAmount'>
-
-const getRedeemableAmount = (bets: RedeemableBet[]) => {
-  const [yesBets, noBets] = partition(bets, (b) => b.outcome === 'YES')
-  const yesShares = sumBy(yesBets, (b) => b.shares)
-  const noShares = sumBy(noBets, (b) => b.shares)
-  const shares = Math.max(Math.min(yesShares, noShares), 0)
-  const loanAmount = sumBy(bets, (bet) => bet.loanAmount ?? 0)
-  const loanPayment = Math.min(loanAmount, shares)
-  const netAmount = shares - loanPayment
-  return { shares, loanPayment, netAmount }
-}
-
-const getRedemptionBets = (
-  shares: number,
-  loanPayment: number,
-  contract: CPMMContract
-) => {
-  const p = getProbability(contract)
-  const createdTime = Date.now()
-  const yesBet: CandidateBet<Bet> = {
-    contractId: contract.id,
-    amount: p * -shares,
-    shares: -shares,
-    loanAmount: loanPayment ? -loanPayment / 2 : 0,
-    outcome: 'YES',
-    probBefore: p,
-    probAfter: p,
-    createdTime,
-    isRedemption: true,
-    fees: noFees,
-  }
-  const noBet: CandidateBet<Bet> = {
-    contractId: contract.id,
-    amount: (1 - p) * -shares,
-    shares: -shares,
-    loanAmount: loanPayment ? -loanPayment / 2 : 0,
-    outcome: 'NO',
-    probBefore: p,
-    probAfter: p,
-    createdTime,
-    isRedemption: true,
-    fees: noFees,
-  }
-  return [yesBet, noBet]
-}
-
 export const redeemShares = async (userId: string, contractId: string) => {
   return await firestore.runTransaction(async (trans) => {
     const contractDoc = firestore.doc(`contracts/${contractId}`)