75 lines
2.4 KiB
TypeScript
75 lines
2.4 KiB
TypeScript
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import * as functions from 'firebase-functions'
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import * as admin from 'firebase-admin'
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import { Contract } from './types/contract'
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import { User } from './types/user'
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import { Bet } from './types/bet'
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export const placeBet = functions.https.onCall(async (data: {
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amount: number
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outcome: string
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contractId: string
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}, context) => {
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const userId = context?.auth?.uid
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if (!userId)
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return { status: 'error', message: 'Not authorized' }
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const { amount, outcome, contractId } = data
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if (outcome !== 'YES' && outcome !== 'NO')
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return { status: 'error', message: 'Invalid outcome' }
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// run as transaction to prevent race conditions
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return await firestore.runTransaction(async transaction => {
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const userDoc = firestore.doc(`users/${userId}`)
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const userSnap = await transaction.get(userDoc)
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if (!userSnap.exists) return { status: 'error', message: 'User not found' }
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const user = userSnap.data() as User
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if (user.balanceUsd < amount)
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return { status: 'error', message: 'Insufficient balance' }
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const contractDoc = firestore.doc(`contracts/${contractId}`)
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const contractSnap = await transaction.get(contractDoc)
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if (!contractSnap.exists) return { status: 'error', message: 'Invalid contract' }
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const contract = contractSnap.data() as Contract
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const newBetDoc = firestore.collection(`contracts/${contractId}/bets`).doc()
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const { newBet, newPot, newBalance } = getNewBetInfo(user, outcome, amount, contract, newBetDoc.id)
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transaction.create(newBetDoc, newBet)
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transaction.update(contractDoc, { pot: newPot })
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transaction.update(userDoc, { balanceUsd: newBalance })
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return { status: 'success' }
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})
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})
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const firestore = admin.firestore()
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const getNewBetInfo = (user: User, outcome: 'YES' | 'NO', amount: number, contract: Contract, newBetId: string) => {
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const { YES: yesPot, NO: noPot } = contract.pot
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const dpmWeight = outcome === 'YES'
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? amount * Math.pow(noPot, 2) / (Math.pow(yesPot, 2) + amount * yesPot)
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: amount * Math.pow(yesPot, 2) / (Math.pow(noPot, 2) + amount * noPot)
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const newBet: Bet = {
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id: newBetId,
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userId: user.id,
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contractId: contract.id,
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amount,
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dpmWeight,
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outcome,
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createdTime: Date.now()
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}
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const newPot = outcome === 'YES'
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? { YES: yesPot + amount, NO: noPot }
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: { YES: yesPot, NO: noPot + amount }
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const newBalance = user.balanceUsd - amount
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return { newBet, newPot, newBalance }
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}
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