move market logic to common

common/antes.ts

@@ -0,0 +1,19 @@
+export const PHANTOM_ANTE = 200;
+
+export const calcStartPool = (initialProbInt: number, ante?: number) => {
+  const p = initialProbInt / 100.0;
+  const totalAnte = PHANTOM_ANTE + (ante || 0);
+
+  const poolYes =
+    p === 0.5
+      ? p * totalAnte
+      : -(totalAnte * (-p + Math.sqrt((-1 + p) * -p))) / (-1 + 2 * p);
+
+  const poolNo = totalAnte - poolYes;
+
+  const f = PHANTOM_ANTE / totalAnte;
+  const startYes = f * poolYes;
+  const startNo = f * poolNo;
+
+  return { startYes, startNo, poolYes, poolNo };
+};

common/new-bet.ts

@@ -0,0 +1,56 @@
+import { Bet } from "./bet";
+import { Contract } from "./contract";
+import { User } from "./user";
+
+export const getNewBetInfo = (
+  user: User,
+  outcome: "YES" | "NO",
+  amount: number,
+  contract: Contract,
+  newBetId: string
+) => {
+  const { YES: yesPool, NO: noPool } = contract.pool;
+
+  const newPool =
+    outcome === "YES"
+      ? { YES: yesPool + amount, NO: noPool }
+      : { YES: yesPool, NO: noPool + amount };
+
+  const shares =
+    outcome === "YES"
+      ? amount + (amount * noPool ** 2) / (yesPool ** 2 + amount * yesPool)
+      : amount + (amount * yesPool ** 2) / (noPool ** 2 + amount * noPool);
+
+  const { YES: yesShares, NO: noShares } = contract.totalShares;
+
+  const newTotalShares =
+    outcome === "YES"
+      ? { YES: yesShares + shares, NO: noShares }
+      : { YES: yesShares, NO: noShares + shares };
+
+  const { YES: yesBets, NO: noBets } = contract.totalBets;
+
+  const newTotalBets =
+    outcome === "YES"
+      ? { YES: yesBets + amount, NO: noBets }
+      : { YES: yesBets, NO: noBets + amount };
+
+  const probBefore = yesPool ** 2 / (yesPool ** 2 + noPool ** 2);
+  const probAfter = newPool.YES ** 2 / (newPool.YES ** 2 + newPool.NO ** 2);
+
+  const newBet: Bet = {
+    id: newBetId,
+    userId: user.id,
+    contractId: contract.id,
+    amount,
+    shares,
+    outcome,
+    probBefore,
+    probAfter,
+    createdTime: Date.now(),
+  };
+
+  const newBalance = user.balance - amount;
+
+  return { newBet, newPool, newTotalShares, newTotalBets, newBalance };
+};

common/new-contract.ts

@@ -0,0 +1,48 @@
+import { calcStartPool } from "./antes";
+import { Contract } from "./contract";
+import { User } from "./user";
+
+export function getNewContract(
+  id: string,
+  slug: string,
+  creator: User,
+  question: string,
+  description: string,
+  initialProb: number,
+  ante?: number,
+  closeTime?: number
+) {
+  const { startYes, startNo, poolYes, poolNo } = calcStartPool(
+    initialProb,
+    ante
+  );
+
+  const contract: Contract = {
+    id,
+    slug,
+    outcomeType: "BINARY",
+
+    creatorId: creator.id,
+    creatorName: creator.name,
+    creatorUsername: creator.username,
+
+    question: question.trim(),
+    description: description.trim(),
+
+    startPool: { YES: startYes, NO: startNo },
+    pool: { YES: poolYes, NO: poolNo },
+    totalShares: { YES: 0, NO: 0 },
+    totalBets: { YES: 0, NO: 0 },
+    isResolved: false,
+
+    createdTime: Date.now(),
+    lastUpdatedTime: Date.now(),
+
+    volume24Hours: 0,
+    volume7Days: 0,
+  };
+
+  if (closeTime) contract.closeTime = closeTime;
+
+  return contract;
+}

common/payouts.ts

@@ -0,0 +1,128 @@
+import { Bet } from "./bet";
+import { Contract } from "./contract";
+import { CREATOR_FEE, FEES } from "./fees";
+
+export const getCancelPayouts = (truePool: number, bets: Bet[]) => {
+  console.log("resolved N/A, pool M$", truePool);
+
+  const betSum = sumBy(bets, (b) => b.amount);
+
+  return bets.map((bet) => ({
+    userId: bet.userId,
+    payout: (bet.amount / betSum) * truePool,
+  }));
+};
+
+export const getStandardPayouts = (
+  outcome: string,
+  truePool: number,
+  contract: Contract,
+  bets: Bet[]
+) => {
+  const [yesBets, noBets] = partition(bets, (bet) => bet.outcome === "YES");
+  const winningBets = outcome === "YES" ? yesBets : noBets;
+
+  const betSum = sumBy(winningBets, (b) => b.amount);
+
+  if (betSum >= truePool) return getCancelPayouts(truePool, winningBets);
+
+  const creatorPayout = CREATOR_FEE * truePool;
+  console.log(
+    "resolved",
+    outcome,
+    "pool: M$",
+    truePool,
+    "creator fee: M$",
+    creatorPayout
+  );
+
+  const shareDifferenceSum = sumBy(winningBets, (b) => b.shares - b.amount);
+
+  const winningsPool = truePool - betSum;
+
+  const winnerPayouts = winningBets.map((bet) => ({
+    userId: bet.userId,
+    payout:
+      (1 - FEES) *
+      (bet.amount +
+        ((bet.shares - bet.amount) / shareDifferenceSum) * winningsPool),
+  }));
+
+  return winnerPayouts.concat([
+    { userId: contract.creatorId, payout: creatorPayout },
+  ]); // add creator fee
+};
+
+export const getMktPayouts = (
+  truePool: number,
+  contract: Contract,
+  bets: Bet[]
+) => {
+  const p =
+    contract.pool.YES ** 2 / (contract.pool.YES ** 2 + contract.pool.NO ** 2);
+  console.log("Resolved MKT at p=", p, "pool: $M", truePool);
+
+  const [yesBets, noBets] = partition(bets, (bet) => bet.outcome === "YES");
+
+  const weightedBetTotal =
+    p * sumBy(yesBets, (b) => b.amount) +
+    (1 - p) * sumBy(noBets, (b) => b.amount);
+
+  if (weightedBetTotal >= truePool) {
+    return bets.map((bet) => ({
+      userId: bet.userId,
+      payout:
+        (((bet.outcome === "YES" ? p : 1 - p) * bet.amount) /
+          weightedBetTotal) *
+        truePool,
+    }));
+  }
+
+  const winningsPool = truePool - weightedBetTotal;
+
+  const weightedShareTotal =
+    p * sumBy(yesBets, (b) => b.shares - b.amount) +
+    (1 - p) * sumBy(noBets, (b) => b.shares - b.amount);
+
+  const yesPayouts = yesBets.map((bet) => ({
+    userId: bet.userId,
+    payout:
+      (1 - FEES) *
+      (p * bet.amount +
+        ((p * (bet.shares - bet.amount)) / weightedShareTotal) * winningsPool),
+  }));
+
+  const noPayouts = noBets.map((bet) => ({
+    userId: bet.userId,
+    payout:
+      (1 - FEES) *
+      ((1 - p) * bet.amount +
+        (((1 - p) * (bet.shares - bet.amount)) / weightedShareTotal) *
+          winningsPool),
+  }));
+
+  const creatorPayout = CREATOR_FEE * truePool;
+
+  return [
+    ...yesPayouts,
+    ...noPayouts,
+    { userId: contract.creatorId, payout: creatorPayout },
+  ];
+};
+
+const partition = <T>(array: T[], f: (t: T) => boolean) => {
+  const yes = [];
+  const no = [];
+
+  for (let t of array) {
+    if (f(t)) yes.push(t);
+    else no.push(t);
+  }
+
+  return [yes, no] as [T[], T[]];
+};
+
+const sumBy = <T>(array: T[], f: (t: T) => number) => {
+  const values = array.map(f);
+  return values.reduce((prev, cur) => prev + cur, 0);
+};

common/sell-bet.ts

@@ -0,0 +1,108 @@
+import { Bet } from "./bet";
+import { Contract } from "./contract";
+import { CREATOR_FEE, PLATFORM_FEE } from "./fees";
+import { User } from "./user";
+
+export const getSellBetInfo = (
+  user: User,
+  bet: Bet,
+  contract: Contract,
+  newBetId: string
+) => {
+  const { id: betId, amount, shares, outcome } = bet;
+
+  const { YES: yesPool, NO: noPool } = contract.pool;
+  const { YES: yesStart, NO: noStart } = contract.startPool;
+  const { YES: yesShares, NO: noShares } = contract.totalShares;
+  const { YES: yesBets, NO: noBets } = contract.totalBets;
+
+  const [y, n, s] = [yesPool, noPool, shares];
+
+  const shareValue =
+    outcome === "YES"
+      ? // https://www.wolframalpha.com/input/?i=b+%2B+%28b+n%5E2%29%2F%28y+%28-b+%2B+y%29%29+%3D+c+solve+b
+        (n ** 2 +
+          s * y +
+          y ** 2 -
+          Math.sqrt(
+            n ** 4 + (s - y) ** 2 * y ** 2 + 2 * n ** 2 * y * (s + y)
+          )) /
+        (2 * y)
+      : (y ** 2 +
+          s * n +
+          n ** 2 -
+          Math.sqrt(
+            y ** 4 + (s - n) ** 2 * n ** 2 + 2 * y ** 2 * n * (s + n)
+          )) /
+        (2 * n);
+
+  const startPool = yesStart + noStart;
+  const pool = yesPool + noPool - startPool;
+
+  const probBefore = yesPool ** 2 / (yesPool ** 2 + noPool ** 2);
+
+  const f = pool / (probBefore * yesShares + (1 - probBefore) * noShares);
+
+  const myPool = outcome === "YES" ? yesPool - yesStart : noPool - noStart;
+
+  const adjShareValue = Math.min(Math.min(1, f) * shareValue, myPool);
+
+  const newPool =
+    outcome === "YES"
+      ? { YES: yesPool - adjShareValue, NO: noPool }
+      : { YES: yesPool, NO: noPool - adjShareValue };
+
+  const newTotalShares =
+    outcome === "YES"
+      ? { YES: yesShares - shares, NO: noShares }
+      : { YES: yesShares, NO: noShares - shares };
+
+  const newTotalBets =
+    outcome === "YES"
+      ? { YES: yesBets - amount, NO: noBets }
+      : { YES: yesBets, NO: noBets - amount };
+
+  const probAfter = newPool.YES ** 2 / (newPool.YES ** 2 + newPool.NO ** 2);
+
+  const creatorFee = CREATOR_FEE * adjShareValue;
+  const saleAmount = (1 - CREATOR_FEE - PLATFORM_FEE) * adjShareValue;
+
+  console.log(
+    "SELL M$",
+    amount,
+    outcome,
+    "for M$",
+    saleAmount,
+    "M$/share:",
+    f,
+    "creator fee: M$",
+    creatorFee
+  );
+
+  const newBet: Bet = {
+    id: newBetId,
+    userId: user.id,
+    contractId: contract.id,
+    amount: -adjShareValue,
+    shares: -shares,
+    outcome,
+    probBefore,
+    probAfter,
+    createdTime: Date.now(),
+    sale: {
+      amount: saleAmount,
+      betId,
+    },
+  };
+
+  const newBalance = user.balance + saleAmount;
+
+  return {
+    newBet,
+    newPool,
+    newTotalShares,
+    newTotalBets,
+    newBalance,
+    creatorFee,
+  };
+};

functions/src/create-contract.ts

@@ -1,12 +1,11 @@
 import * as functions from 'firebase-functions'
 import * as admin from 'firebase-admin'
 
-import { getUser } from './utils'
+import { chargeUser, getUser } from './utils'
-import { payUser } from '.'
 import { Contract } from '../../common/contract'
-import { User } from '../../common/user'
 import { slugify } from '../../common/util/slugify'
 import { randomString } from '../../common/util/random-string'
+import { getNewContract } from '../../common/new-contract'
 
 export const createContract = functions
   .runWith({ minInstances: 1 })
@@ -62,7 +61,7 @@ export const createContract = functions
         closeTime
       )
 
-      if (ante) await payUser([creator.id, -ante])
+      if (ante) await chargeUser(creator.id, ante)
 
       await contractRef.create(contract)
       return { status: 'success', contract }
@@ -70,7 +69,7 @@ export const createContract = functions
   )
 
 const getSlug = async (question: string) => {
-  const proposedSlug = slugify(question).substring(0, 35)
+  const proposedSlug = slugify(question)
 
   const preexistingContract = await getContractFromSlug(proposedSlug)
 
@@ -79,73 +78,6 @@ const getSlug = async (question: string) => {
     : proposedSlug
 }
 
-function getNewContract(
-  id: string,
-  slug: string,
-  creator: User,
-  question: string,
-  description: string,
-  initialProb: number,
-  ante?: number,
-  closeTime?: number
-) {
-  const { startYes, startNo, poolYes, poolNo } = calcStartPool(
-    initialProb,
-    ante
-  )
-
-  const contract: Contract = {
-    id,
-    slug,
-    outcomeType: 'BINARY',
-
-    creatorId: creator.id,
-    creatorName: creator.name,
-    creatorUsername: creator.username,
-
-    question: question.trim(),
-    description: description.trim(),
-
-    startPool: { YES: startYes, NO: startNo },
-    pool: { YES: poolYes, NO: poolNo },
-    totalShares: { YES: 0, NO: 0 },
-    totalBets: { YES: 0, NO: 0 },
-    isResolved: false,
-
-    createdTime: Date.now(),
-    lastUpdatedTime: Date.now(),
-
-    volume24Hours: 0,
-    volume7Days: 0,
-  }
-
-  if (closeTime) contract.closeTime = closeTime
-
-  return contract
-}
-
-const calcStartPool = (
-  initialProbInt: number,
-  ante?: number,
-  phantomAnte = 200
-) => {
-  const p = initialProbInt / 100.0
-  const totalAnte = phantomAnte + (ante || 0)
-
-  const poolYes =
-    p === 0.5
-      ? p * totalAnte
-      : -(totalAnte * (-p + Math.sqrt((-1 + p) * -p))) / (-1 + 2 * p)
-
-  const poolNo = totalAnte - poolYes
-
-  const f = phantomAnte / totalAnte
-  const startYes = f * poolYes
-  const startNo = f * poolNo
-
-  return { startYes, startNo, poolYes, poolNo }
-}
-
 const firestore = admin.firestore()
 
 export async function getContractFromSlug(slug: string) {

functions/src/place-bet.ts

@@ -3,7 +3,7 @@ import * as admin from 'firebase-admin'
 
 import { Contract } from '../../common/contract'
 import { User } from '../../common/user'
-import { Bet } from '../../common/bet'
+import { getNewBetInfo } from '../../common/new-bet'
 
 export const placeBet = functions.runWith({ minInstances: 1 }).https.onCall(
   async (
@@ -67,56 +67,3 @@ export const placeBet = functions.runWith({ minInstances: 1 }).https.onCall(
 )
 
 const firestore = admin.firestore()
-
-const getNewBetInfo = (
-  user: User,
-  outcome: 'YES' | 'NO',
-  amount: number,
-  contract: Contract,
-  newBetId: string
-) => {
-  const { YES: yesPool, NO: noPool } = contract.pool
-
-  const newPool =
-    outcome === 'YES'
-      ? { YES: yesPool + amount, NO: noPool }
-      : { YES: yesPool, NO: noPool + amount }
-
-  const shares =
-    outcome === 'YES'
-      ? amount + (amount * noPool ** 2) / (yesPool ** 2 + amount * yesPool)
-      : amount + (amount * yesPool ** 2) / (noPool ** 2 + amount * noPool)
-
-  const { YES: yesShares, NO: noShares } = contract.totalShares
-
-  const newTotalShares =
-    outcome === 'YES'
-      ? { YES: yesShares + shares, NO: noShares }
-      : { YES: yesShares, NO: noShares + shares }
-
-  const { YES: yesBets, NO: noBets } = contract.totalBets
-
-  const newTotalBets =
-    outcome === 'YES'
-      ? { YES: yesBets + amount, NO: noBets }
-      : { YES: yesBets, NO: noBets + amount }
-
-  const probBefore = yesPool ** 2 / (yesPool ** 2 + noPool ** 2)
-  const probAfter = newPool.YES ** 2 / (newPool.YES ** 2 + newPool.NO ** 2)
-
-  const newBet: Bet = {
-    id: newBetId,
-    userId: user.id,
-    contractId: contract.id,
-    amount,
-    shares,
-    outcome,
-    probBefore,
-    probAfter,
-    createdTime: Date.now(),
-  }
-
-  const newBalance = user.balance - amount
-
-  return { newBet, newPool, newTotalShares, newTotalBets, newBalance }
-}

functions/src/sell-bet.ts

@@ -1,10 +1,10 @@
 import * as admin from 'firebase-admin'
 import * as functions from 'firebase-functions'
 
-import { CREATOR_FEE, PLATFORM_FEE } from '../../common/fees'
 import { Contract } from '../../common/contract'
 import { User } from '../../common/user'
 import { Bet } from '../../common/bet'
+import { getSellBetInfo } from '../../common/sell-bet'
 
 export const sellBet = functions.runWith({ minInstances: 1 }).https.onCall(
   async (
@@ -80,107 +80,3 @@ export const sellBet = functions.runWith({ minInstances: 1 }).https.onCall(
 )
 
 const firestore = admin.firestore()
-
-const getSellBetInfo = (
-  user: User,
-  bet: Bet,
-  contract: Contract,
-  newBetId: string
-) => {
-  const { id: betId, amount, shares, outcome } = bet
-
-  const { YES: yesPool, NO: noPool } = contract.pool
-  const { YES: yesStart, NO: noStart } = contract.startPool
-  const { YES: yesShares, NO: noShares } = contract.totalShares
-  const { YES: yesBets, NO: noBets } = contract.totalBets
-
-  const [y, n, s] = [yesPool, noPool, shares]
-
-  const shareValue =
-    outcome === 'YES'
-      ? // https://www.wolframalpha.com/input/?i=b+%2B+%28b+n%5E2%29%2F%28y+%28-b+%2B+y%29%29+%3D+c+solve+b
-        (n ** 2 +
-          s * y +
-          y ** 2 -
-          Math.sqrt(
-            n ** 4 + (s - y) ** 2 * y ** 2 + 2 * n ** 2 * y * (s + y)
-          )) /
-        (2 * y)
-      : (y ** 2 +
-          s * n +
-          n ** 2 -
-          Math.sqrt(
-            y ** 4 + (s - n) ** 2 * n ** 2 + 2 * y ** 2 * n * (s + n)
-          )) /
-        (2 * n)
-
-  const startPool = yesStart + noStart
-  const pool = yesPool + noPool - startPool
-
-  const probBefore = yesPool ** 2 / (yesPool ** 2 + noPool ** 2)
-
-  const f = pool / (probBefore * yesShares + (1 - probBefore) * noShares)
-
-  const myPool = outcome === 'YES' ? yesPool - yesStart : noPool - noStart
-
-  const adjShareValue = Math.min(Math.min(1, f) * shareValue, myPool)
-
-  const newPool =
-    outcome === 'YES'
-      ? { YES: yesPool - adjShareValue, NO: noPool }
-      : { YES: yesPool, NO: noPool - adjShareValue }
-
-  const newTotalShares =
-    outcome === 'YES'
-      ? { YES: yesShares - shares, NO: noShares }
-      : { YES: yesShares, NO: noShares - shares }
-
-  const newTotalBets =
-    outcome === 'YES'
-      ? { YES: yesBets - amount, NO: noBets }
-      : { YES: yesBets, NO: noBets - amount }
-
-  const probAfter = newPool.YES ** 2 / (newPool.YES ** 2 + newPool.NO ** 2)
-
-  const creatorFee = CREATOR_FEE * adjShareValue
-  const saleAmount = (1 - CREATOR_FEE - PLATFORM_FEE) * adjShareValue
-
-  console.log(
-    'SELL M$',
-    amount,
-    outcome,
-    'for M$',
-    saleAmount,
-    'M$/share:',
-    f,
-    'creator fee: M$',
-    creatorFee
-  )
-
-  const newBet: Bet = {
-    id: newBetId,
-    userId: user.id,
-    contractId: contract.id,
-    amount: -adjShareValue,
-    shares: -shares,
-    outcome,
-    probBefore,
-    probAfter,
-    createdTime: Date.now(),
-    sale: {
-      amount: saleAmount,
-      betId,
-    },
-  }
-
-  const newBalance = user.balance + saleAmount
-
-  return {
-    newBet,
-    newPool,
-    newTotalShares,
-    newTotalBets,
-    newBalance,
-    creatorFee,
-  }
-}