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