mechanism-agnostic calculations

common/calculate.ts

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+import { Bet } from './bet'
+import {
+  calculateCpmmShares,
+  getCpmmProbability,
+  getCpmmProbabilityAfterBet,
+} from './calculate-cpmm'
+import {
+  calculateDpmPayoutAfterCorrectBet,
+  calculateDpmShares,
+  getDpmOutcomeProbability,
+  getDpmProbability,
+  getDpmProbabilityAfterBet,
+} from './calculate-dpm'
+import { Binary, Contract, CPMM, DPM, FullContract } from './contract'
+import { FEES } from './fees'
+
+export function getProbability(contract: FullContract<DPM | CPMM, Binary>) {
+  return contract.mechanism === 'cpmm-1'
+    ? getCpmmProbability(contract.pool)
+    : getDpmProbability(contract.totalShares)
+}
+
+export function getOutcomeProbability(contract: Contract, outcome: string) {
+  return contract.mechanism === 'cpmm-1'
+    ? getCpmmProbability(contract.pool)
+    : getDpmOutcomeProbability(contract.totalShares, outcome)
+}
+
+export function getProbabilityAfterBet(
+  contract: Contract,
+  outcome: string,
+  bet: number
+) {
+  return contract.mechanism === 'cpmm-1'
+    ? getCpmmProbabilityAfterBet(
+        contract as FullContract<CPMM, Binary>,
+        outcome,
+        bet
+      )
+    : getDpmProbabilityAfterBet(contract.totalShares, outcome, bet)
+}
+
+export function calculateShares(
+  contract: Contract,
+  bet: number,
+  betChoice: string
+) {
+  return contract.mechanism === 'cpmm-1'
+    ? calculateCpmmShares(contract.pool, contract.k, bet, betChoice)
+    : calculateDpmShares(contract.totalShares, bet, betChoice)
+}
+
+export function calculatePayoutAfterCorrectBet(contract: Contract, bet: Bet) {
+  return contract.mechanism === 'cpmm-1'
+    ? deductFees(bet.amount, bet.shares)
+    : calculateDpmPayoutAfterCorrectBet(contract, bet)
+}
+
+export const deductFees = (betAmount: number, winnings: number) => {
+  return winnings > betAmount
+    ? betAmount + (1 - FEES) * (winnings - betAmount)
+    : winnings
+}