From d38453b29ac1d3cc9fb2526280df23c220f22dc1 Mon Sep 17 00:00:00 2001
From: mantikoros <sgrugett@gmail.com>
Date: Fri, 6 May 2022 16:39:46 -0400
Subject: [PATCH] placeBet for numeric markets

---
 common/calculate-dpm.ts    | 28 +++++++++++++++++++++++
 common/new-bet.ts          | 46 ++++++++++++++++++++++++++++++++++++++
 functions/src/place-bet.ts | 16 ++++++++++++-
 3 files changed, 89 insertions(+), 1 deletion(-)

diff --git a/common/calculate-dpm.ts b/common/calculate-dpm.ts
index 6dbd75da..a37bab15 100644
--- a/common/calculate-dpm.ts
+++ b/common/calculate-dpm.ts
@@ -9,6 +9,7 @@ import {
 } from './contract'
 import { DPM_FEES } from './fees'
 import { normpdf } from './normal'
+import { addObjects } from './util/object'
 
 export function getDpmProbability(totalShares: { [outcome: string]: number }) {
   // For binary contracts only.
@@ -106,6 +107,33 @@ export function calculateDpmShares(
   return Math.sqrt(bet ** 2 + shares ** 2 + c) - shares
 }
 
+const zigZagOrder = (length: number) => {
+  const mid = Math.floor(length / 2)
+
+  return _.range(0, mid)
+    .flatMap((i) => [i, length - i - 1])
+    .concat(length % 2 === 0 ? [] : [mid])
+}
+
+export function calculateNumericDpmShares(
+  totalShares: {
+    [outcome: string]: number
+  },
+  bets: [string, number][]
+) {
+  const shares: number[] = []
+
+  totalShares = _.cloneDeep(totalShares)
+
+  for (let i of zigZagOrder(bets.length)) {
+    const [bucket, bet] = bets[i]
+    shares[i] = calculateDpmShares(totalShares, bet, bucket)
+    totalShares = addObjects(totalShares, { [bucket]: shares[i] })
+  }
+
+  return { shares, totalShares }
+}
+
 export function calculateDpmRawShareValue(
   totalShares: {
     [outcome: string]: number
diff --git a/common/new-bet.ts b/common/new-bet.ts
index 92feb715..33acd2dc 100644
--- a/common/new-bet.ts
+++ b/common/new-bet.ts
@@ -5,6 +5,8 @@ import {
   calculateDpmShares,
   getDpmProbability,
   getDpmOutcomeProbability,
+  getNumericBets,
+  calculateNumericDpmShares,
 } from './calculate-dpm'
 import { calculateCpmmPurchase, getCpmmProbability } from './calculate-cpmm'
 import {
@@ -14,9 +16,11 @@ import {
   FreeResponse,
   FullContract,
   Multi,
+  NumericContract,
 } from './contract'
 import { User } from './user'
 import { noFees } from './fees'
+import { addObjects } from './util/object'
 
 export const getNewBinaryCpmmBetInfo = (
   user: User,
@@ -154,6 +158,48 @@ export const getNewMultiBetInfo = (
   return { newBet, newPool, newTotalShares, newTotalBets, newBalance }
 }
 
+export const getNumericBetsInfo = (
+  user: User,
+  outcome: string,
+  amount: number,
+  contract: NumericContract
+) => {
+  const { pool, totalShares, totalBets } = contract
+
+  const bets = getNumericBets(contract, outcome, amount)
+  const newPool = addObjects(pool, Object.fromEntries(bets))
+
+  const { shares, totalShares: newTotalShares } = calculateNumericDpmShares(
+    contract.totalShares,
+    bets
+  )
+
+  const newTotalBets = addObjects(totalBets, Object.fromEntries(bets))
+
+  const newBets = bets.map(([outcome, amount], i) => {
+    const probBefore = getDpmOutcomeProbability(totalShares, outcome)
+    const probAfter = getDpmOutcomeProbability(newTotalShares, outcome)
+
+    const newBet: Omit<Bet, 'id'> = {
+      userId: user.id,
+      contractId: contract.id,
+      amount,
+      shares: shares[i],
+      outcome,
+      probBefore,
+      probAfter,
+      createdTime: Date.now(),
+      fees: noFees,
+    }
+
+    return newBet
+  })
+
+  const newBalance = user.balance - amount
+
+  return { newBets, newPool, newTotalShares, newTotalBets, newBalance }
+}
+
 export const getLoanAmount = (yourBets: Bet[], newBetAmount: number) => {
   const openBets = yourBets.filter((bet) => !bet.isSold && !bet.sale)
   const prevLoanAmount = _.sumBy(openBets, (bet) => bet.loanAmount ?? 0)
diff --git a/functions/src/place-bet.ts b/functions/src/place-bet.ts
index 74487126..5da8ac57 100644
--- a/functions/src/place-bet.ts
+++ b/functions/src/place-bet.ts
@@ -8,6 +8,7 @@ import {
   getNewBinaryDpmBetInfo,
   getNewMultiBetInfo,
   getLoanAmount,
+  getNumericBetsInfo,
 } from '../../common/new-bet'
 import { addObjects, removeUndefinedProps } from '../../common/util/object'
 import { Bet } from '../../common/bet'
@@ -77,6 +78,7 @@ export const placeBet = functions.runWith({ minInstances: 1 }).https.onCall(
 
         const {
           newBet,
+          newBets,
           newPool,
           newTotalShares,
           newTotalBets,
@@ -103,6 +105,8 @@ export const placeBet = functions.runWith({ minInstances: 1 }).https.onCall(
                   loanAmount,
                   newBetDoc.id
                 ) as any)
+            : outcomeType === 'NUMERIC' && mechanism === 'dpm-2'
+            ? getNumericBetsInfo(user, outcome, amount, contract)
             : getNewMultiBetInfo(
                 user,
                 outcome,
@@ -119,7 +123,17 @@ export const placeBet = functions.runWith({ minInstances: 1 }).https.onCall(
           }
         }
 
-        transaction.create(newBetDoc, newBet)
+        if (newBet) transaction.create(newBetDoc, newBet)
+
+        if (newBets) {
+          for (let newBet of newBets) {
+            const newBetDoc = firestore
+              .collection(`contracts/${contractId}/bets`)
+              .doc()
+
+            transaction.create(newBetDoc, { id: newBetDoc.id, ...newBet })
+          }
+        }
 
         transaction.update(
           contractDoc,