manifold/common/loans.ts
2022-08-19 15:22:10 -05:00

89 lines
2.5 KiB
TypeScript

import { Dictionary, groupBy, sumBy, minBy } from 'lodash'
import { Bet } from './bet'
import { getContractBetMetrics } from './calculate'
import { Contract, CPMMContract, FreeResponseContract, MultipleChoiceContract } from './contract'
import { filterDefined } from './util/array'
export const getUserLoanUpdates = (
bets: Bet[],
contractsById: Dictionary<Contract>
) => {
const betsByContract = groupBy(bets, (bet) => bet.contractId)
const contracts = filterDefined(
Object.keys(betsByContract).map((contractId) => contractsById[contractId])
)
const betUpdates = filterDefined(
contracts
.map((c) => {
if (c.mechanism === 'cpmm-1') {
return getBinaryContractLoanUpdate(c, betsByContract[c.id])
} else if (
c.outcomeType === 'FREE_RESPONSE' ||
c.outcomeType === 'MULTIPLE_CHOICE'
)
return getFreeResponseContractLoanUpdate(c, betsByContract[c.id])
else {
// Unsupported contract / mechanism for loans.
return []
}
})
.flat()
)
const totalNewLoan = sumBy(betUpdates, (loanUpdate) => loanUpdate.loanTotal)
return {
totalNewLoan,
betUpdates,
}
}
const getBinaryContractLoanUpdate = (contract: CPMMContract, bets: Bet[]) => {
const { invested } = getContractBetMetrics(contract, bets)
const loanAmount = sumBy(bets, (bet) => bet.loanAmount ?? 0)
const oldestBet = minBy(bets, (bet) => bet.createdTime)
const newLoan = calculateNewLoan(invested, loanAmount)
if (isNaN(newLoan) || newLoan <= 0 || !oldestBet) return undefined
const loanTotal = (oldestBet.loanAmount ?? 0) + newLoan
return {
userId: oldestBet.userId,
contractId: contract.id,
betId: oldestBet.id,
newLoan,
loanTotal,
}
}
const getFreeResponseContractLoanUpdate = (
contract: FreeResponseContract | MultipleChoiceContract,
bets: Bet[]
) => {
const openBets = bets.filter((bet) => bet.isSold || bet.sale)
return openBets.map((bet) => {
const loanAmount = bet.loanAmount ?? 0
const newLoan = calculateNewLoan(bet.amount, loanAmount)
const loanTotal = loanAmount + newLoan
if (isNaN(newLoan) || newLoan <= 0) return undefined
return {
userId: bet.userId,
contractId: contract.id,
betId: bet.id,
newLoan,
loanTotal,
}
})
}
const LOAN_WEEKLY_RATE = 0.05
const calculateNewLoan = (investedValue: number, loanTotal: number) => {
const netValue = investedValue - loanTotal
return netValue * LOAN_WEEKLY_RATE
}