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Refactor share redemption code into a few sensible functions

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This commit is contained in:
Marshall Polaris 2022-07-02 17:14:01 -07:00
parent 8fdc44f7f3
commit 1b1a8ca18e
1 changed files with 63 additions and 66 deletions
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129
functions/src/redeem-shares.ts
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@ -4,93 +4,90 @@ import { partition, sumBy } from 'lodash'
import { Bet } from '../../common/bet'
import { getProbability } from '../../common/calculate'
import { Contract } from '../../common/contract'
import { Contract, CPMMContract } 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 (transaction) => {
return await firestore.runTransaction(async (trans) => {
const contractDoc = firestore.doc(`contracts/${contractId}`)
const contractSnap = await transaction.get(contractDoc)
const contractSnap = await trans.get(contractDoc)
if (!contractSnap.exists)
return { status: 'error', message: 'Invalid contract' }
const contract = contractSnap.data() as Contract
const { mechanism, outcomeType } = contract
if (
!(outcomeType === 'BINARY' || outcomeType === 'PSEUDO_NUMERIC') ||
mechanism !== 'cpmm-1'
)
return { status: 'success' }
const { mechanism } = contract
if (mechanism !== 'cpmm-1') return { status: 'success' }
const betsSnap = await transaction.get(
firestore
.collection(`contracts/${contract.id}/bets`)
.where('userId', '==', userId)
)
const betsColl = firestore.collection(`contracts/${contract.id}/bets`)
const betsSnap = await trans.get(betsColl.where('userId', '==', userId))
const bets = betsSnap.docs.map((doc) => doc.data() as Bet)
const [yesBets, noBets] = partition(bets, (b) => b.outcome === 'YES')
const yesShares = sumBy(yesBets, (b) => b.shares)
const noShares = sumBy(noBets, (b) => b.shares)
const amount = Math.min(yesShares, noShares)
if (amount <= 0) return
const prevLoanAmount = sumBy(bets, (bet) => bet.loanAmount ?? 0)
const loanPaid = Math.min(prevLoanAmount, amount)
const netAmount = amount - loanPaid
const p = getProbability(contract)
const createdTime = Date.now()
const yesDoc = firestore.collection(`contracts/${contract.id}/bets`).doc()
const yesBet: Bet = {
id: yesDoc.id,
userId: userId,
contractId: contract.id,
amount: p * -amount,
shares: -amount,
loanAmount: loanPaid ? -loanPaid / 2 : 0,
outcome: 'YES',
probBefore: p,
probAfter: p,
createdTime,
isRedemption: true,
fees: noFees,
}
const noDoc = firestore.collection(`contracts/${contract.id}/bets`).doc()
const noBet: Bet = {
id: noDoc.id,
userId: userId,
contractId: contract.id,
amount: (1 - p) * -amount,
shares: -amount,
loanAmount: loanPaid ? -loanPaid / 2 : 0,
outcome: 'NO',
probBefore: p,
probAfter: p,
createdTime,
isRedemption: true,
fees: noFees,
}
const { shares, loanPayment, netAmount } = getRedeemableAmount(bets)
const [yesBet, noBet] = getRedemptionBets(shares, loanPayment, contract)
const userDoc = firestore.doc(`users/${userId}`)
const userSnap = await transaction.get(userDoc)
const userSnap = await trans.get(userDoc)
if (!userSnap.exists) return { status: 'error', message: 'User not found' }
const user = userSnap.data() as User
const newBalance = user.balance + netAmount
if (!isFinite(newBalance)) {
throw new Error('Invalid user balance for ' + user.username)
}
transaction.update(userDoc, { balance: newBalance })
transaction.create(yesDoc, yesBet)
transaction.create(noDoc, noBet)
const yesDoc = betsColl.doc()
const noDoc = betsColl.doc()
trans.update(userDoc, { balance: newBalance })
trans.create(yesDoc, { id: yesDoc.id, userId, ...yesBet })
trans.create(noDoc, { id: noDoc.id, userId, ...noBet })
return { status: 'success' }
})