manifold/functions/src/cancel-bet.ts

import * as admin from 'firebase-admin'
import { z } from 'zod'
import { APIError, newEndpoint, validate } from './api'
import { LimitBet } from '../../common/bet'

const bodySchema = z.object({
  betId: z.string(),
})

export const cancelbet = newEndpoint({}, async (req, auth) => {
  const { betId } = validate(bodySchema, req.body)

  const result = await firestore.runTransaction(async (trans) => {
    const snap = await trans.get(
      firestore.collectionGroup('bets').where('id', '==', betId)
    )
    const betDoc = snap.docs[0]
    if (!betDoc?.exists) throw new APIError(400, 'Bet not found.')

    const bet = betDoc.data() as LimitBet
    if (bet.userId !== auth.uid)
      throw new APIError(400, 'Not authorized to cancel bet.')
    if (bet.limitProb === undefined)
      throw new APIError(400, 'Not a limit order: Cannot cancel.')
    if (bet.isCancelled) throw new APIError(400, 'Bet already cancelled.')

    trans.update(betDoc.ref, { isCancelled: true })

    return { ...bet, isCancelled: true }
  })

  return result
})

const firestore = admin.firestore()