import * as functions from 'firebase-functions'
import * as admin from 'firebase-admin'
import * as _ from 'lodash'

import { Contract } from './types/contract'
import { User } from './types/user'
import { Bet } from './types/bet'

export const PLATFORM_FEE = 0.01 // 1%
export const CREATOR_FEE = 0.01 // 1%

export const resolveMarket = functions
  .runWith({ minInstances: 1 })
  .https
  .onCall(async (data: {
    outcome: string
    contractId: string
  }, context) => {
    const userId = context?.auth?.uid
    if (!userId) return { status: 'error', message: 'Not authorized' }

    const { outcome, contractId } = data

    if (!['YES', 'NO', 'CANCEL'].includes(outcome))
      return { status: 'error', message: 'Invalid outcome' }

    const contractDoc = firestore.doc(`contracts/${contractId}`)
    const contractSnap = await contractDoc.get()
    if (!contractSnap.exists)
      return { status: 'error', message: 'Invalid contract' }
    const contract = contractSnap.data() as Contract

    if (contract.creatorId !== userId)
      return { status: 'error', message: 'User not creator of contract' }

    if (contract.resolution)
      return { status: 'error', message: 'Contract already resolved' }

    await contractDoc.update({
      isResolved: true,
      resolution: outcome,
      resolutionTime: Date.now()
    })

    console.log('contract ', contractId, 'resolved to:', outcome)

    const betsSnap = await firestore.collection(`contracts/${contractId}/bets`).get()
    const bets = betsSnap.docs.map(doc => doc.data() as Bet)

    const payouts = outcome === 'CANCEL'
      ? bets.map(bet => ({
        userId: bet.userId,
        payout: bet.amount
      }))

      : getPayouts(outcome, contract, bets)

    console.log('payouts:', payouts)

    const groups = _.groupBy(payouts, payout => payout.userId)
    const userPayouts = _.mapValues(groups, group => _.sumBy(group, g => g.payout))

    const payoutPromises = Object
      .entries(userPayouts)
      .map(payUser)

    return await Promise.all(payoutPromises)
      .catch(e => ({ status: 'error', message: e }))
      .then(() => ({ status: 'success' }))
  })

const firestore = admin.firestore()

const getPayouts = (outcome: string, contract: Contract, bets: Bet[]) => {
  const [yesBets, noBets] = _.partition(bets, bet => bet.outcome === 'YES')

  const [pot, winningBets] = outcome === 'YES'
    ? [contract.pot.NO, yesBets]
    : [contract.pot.YES, noBets]

  const finalPot = (1 - PLATFORM_FEE - CREATOR_FEE) * pot
  const creatorPayout = CREATOR_FEE * pot
  console.log('final pot:', finalPot, 'creator fee:', creatorPayout)

  const sumWeights = _.sumBy(winningBets, bet => bet.dpmWeight)

  const winnerPayouts = winningBets.map(bet => ({
    userId: bet.userId,
    payout: bet.amount + (bet.dpmWeight / sumWeights * finalPot)
  }))

  return winnerPayouts
    .concat([{ userId: contract.creatorId, payout: creatorPayout }]) // add creator fee
}

const payUser = ([userId, payout]: [string, number]) => {
  return firestore.runTransaction(async transaction => {
    const userDoc = firestore.doc(`users/${userId}`)
    const userSnap = await transaction.get(userDoc)
    if (!userSnap.exists) return
    const user = userSnap.data() as User

    const newUserBalance = user.balance + payout
    transaction.update(userDoc, { balance: newUserBalance })
  })
}