Include answer probabilities in FreeResponse API results (#526)

* Include answer probabilities in FreeResponse API results

* Appease ESLint

web/lib/firebase/contracts.ts

@@ -18,7 +18,7 @@ import { range, sortBy, sum } from 'lodash'
 
 import { app } from './init'
 import { getValues, listenForValue, listenForValues } from './utils'
-import { BinaryContract, Contract, FreeResponseContract } from 'common/contract'
+import { BinaryContract, Contract } from 'common/contract'
 import { getDpmProbability } from 'common/calculate-dpm'
 import { createRNG, shuffle } from 'common/util/random'
 import { getCpmmProbability } from 'common/calculate-cpmm'
@@ -28,7 +28,7 @@ import { MAX_FEED_CONTRACTS } from 'common/recommended-contracts'
 import { Bet } from 'common/bet'
 import { Comment } from 'common/comment'
 import { ENV_CONFIG } from 'common/envs/constants'
-export type { Contract, FreeResponseContract }
+export type { Contract }
 
 export function contractPath(contract: Contract) {
   return `/${contract.creatorUsername}/${contract.slug}`

web/pages/api/v0/_types.ts

@@ -1,6 +1,6 @@
 import { Bet } from 'common/bet'
 import { Answer } from 'common/answer'
-import { getProbability } from 'common/calculate'
+import { getOutcomeProbability, getProbability } from 'common/calculate'
 import { Comment } from 'common/comment'
 import { Contract } from 'common/contract'
 import { removeUndefinedProps } from 'common/util/object'
@@ -38,10 +38,14 @@ export type LiteMarket = {
   resolutionTime?: number
 }
 
+export type ApiAnswer = Answer & {
+  probability?: number
+}
+
 export type FullMarket = LiteMarket & {
   bets: Exclude<Bet, 'userId'>[]
   comments: Comment[]
-  answers?: Answer[]
+  answers?: ApiAnswer[]
 }
 
 export type ApiError = {
@@ -104,3 +108,35 @@ export function toLiteMarket(contract: Contract): LiteMarket {
     resolutionTime,
   })
 }
+
+export function toFullMarket(
+  contract: Contract,
+  comments: Comment[],
+  bets: Bet[]
+): FullMarket {
+  const liteMarket = toLiteMarket(contract)
+  const answers =
+    contract.outcomeType === 'FREE_RESPONSE'
+      ? contract.answers.map((answer) =>
+          augmentAnswerWithProbability(contract, answer)
+        )
+      : undefined
+
+  return {
+    ...liteMarket,
+    answers,
+    comments,
+    bets,
+  }
+}
+
+function augmentAnswerWithProbability(
+  contract: Contract,
+  answer: Answer
+): ApiAnswer {
+  const probability = getOutcomeProbability(contract, answer.id)
+  return {
+    ...answer,
+    probability,
+  }
+}

web/pages/api/v0/market/[id].ts

@@ -1,12 +1,9 @@
 import { NextApiRequest, NextApiResponse } from 'next'
 import { Bet, listAllBets } from 'web/lib/firebase/bets'
 import { listAllComments } from 'web/lib/firebase/comments'
-import {
-  getContractFromId,
-  FreeResponseContract,
-} from 'web/lib/firebase/contracts'
+import { getContractFromId } from 'web/lib/firebase/contracts'
 import { applyCorsHeaders, CORS_UNRESTRICTED } from 'web/lib/api/cors'
-import { FullMarket, ApiError, toLiteMarket } from '../_types'
+import { FullMarket, ApiError, toFullMarket } from '../_types'
 
 export default async function handler(
   req: NextApiRequest,
@@ -28,8 +25,6 @@ export default async function handler(
     'userId'
   >[]
 
-  const answers = (contract as FreeResponseContract).answers
-
   if (!contract) {
     res.status(404).json({ error: 'Contract not found' })
     return
@@ -37,10 +32,5 @@ export default async function handler(
 
   // Cache on Vercel edge servers for 2min
   res.setHeader('Cache-Control', 'max-age=0, s-maxage=120')
-  return res.status(200).json({
-    ...toLiteMarket(contract),
-    bets,
-    comments,
-    answers,
-  })
+  return res.status(200).json(toFullMarket(contract, comments, bets))
 }

web/pages/api/v0/slug/[slug].ts

@@ -2,11 +2,8 @@ import { NextApiRequest, NextApiResponse } from 'next'
 import { applyCorsHeaders, CORS_UNRESTRICTED } from 'web/lib/api/cors'
 import { Bet, listAllBets } from 'web/lib/firebase/bets'
 import { listAllComments } from 'web/lib/firebase/comments'
-import {
-  getContractFromSlug,
-  FreeResponseContract,
-} from 'web/lib/firebase/contracts'
-import { FullMarket, ApiError, toLiteMarket } from '../_types'
+import { getContractFromSlug } from 'web/lib/firebase/contracts'
+import { FullMarket, ApiError, toFullMarket } from '../_types'
 
 export default async function handler(
   req: NextApiRequest,
@@ -27,8 +24,6 @@ export default async function handler(
     listAllComments(contract.id),
   ])
 
-  const answers = (contract as FreeResponseContract).answers
-
   // eslint-disable-next-line @typescript-eslint/no-unused-vars
   const bets = allBets.map(({ userId, ...bet }) => bet) as Exclude<
     Bet,
@@ -37,10 +32,5 @@ export default async function handler(
 
   // Cache on Vercel edge servers for 2min
   res.setHeader('Cache-Control', 'max-age=0, s-maxage=120')
-  return res.status(200).json({
-    ...toLiteMarket(contract),
-    bets,
-    comments,
-    answers,
-  })
+  return res.status(200).json(toFullMarket(contract, comments, bets))
 }