manifold/web/lib/service/create-contract.ts
2021-12-17 17:40:32 -06:00

63 lines
1.5 KiB
TypeScript

import {
Contract,
getContractFromSlug,
pushNewContract,
setContract,
} from '../firebase/contracts'
import { User } from '../firebase/users'
import { randomString } from '../util/random-string'
import { slugify } from '../util/slugify'
// consider moving to cloud function for security
export async function createContract(
question: string,
description: string,
initialProb: number,
creator: User
) {
const proposedSlug = slugify(question).substring(0, 35)
const preexistingContract = await getContractFromSlug(proposedSlug)
const slug = preexistingContract
? proposedSlug + '-' + randomString()
: proposedSlug
const { startYes, startNo } = calcStartPool(initialProb)
const contract: Omit<Contract, 'id'> = {
slug,
outcomeType: 'BINARY',
creatorId: creator.id,
creatorName: creator.name,
question: question.trim(),
description: description.trim(),
startPool: { YES: startYes, NO: startNo },
pool: { YES: startYes, NO: startNo },
dpmWeights: { YES: 0, NO: 0 },
isResolved: false,
// TODO: Set create time to Firestore timestamp
createdTime: Date.now(),
lastUpdatedTime: Date.now(),
}
return await pushNewContract(contract)
}
export function calcStartPool(initialProb: number, initialCapital = 200) {
const p = initialProb / 100.0
const startYes =
p === 0.5
? p * initialCapital
: -(initialCapital * (-p + Math.sqrt((-1 + p) * -p))) / (-1 + 2 * p)
const startNo = initialCapital - startYes
return { startYes, startNo }
}