From 61f30d4ab933c4ac6a490096b93ba3a6fdf2dfc8 Mon Sep 17 00:00:00 2001
From: mantikoros <sgrugett@gmail.com>
Date: Thu, 3 Mar 2022 00:01:39 -0500
Subject: [PATCH] mechanism-agnostic calculations

---
 common/calculate.ts | 63 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 63 insertions(+)
 create mode 100644 common/calculate.ts

diff --git a/common/calculate.ts b/common/calculate.ts
new file mode 100644
index 00000000..b10906b2
--- /dev/null
+++ b/common/calculate.ts
@@ -0,0 +1,63 @@
+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
+}