manifold/common/redeem.ts

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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]
}