text: import util, { score } from '../util'
  import constants from '../constants'
  
  export default (game, options = {}) => {
    const { TWOBETASQ, EPSILON } = constants(options)
    const { teamRating, gamma } = util(options)
    const teamRatings = teamRating(game)
  
    return teamRatings.map((iTeamRating, i) => {
      const [iMu, iSigmaSq, iTeam, iRank] = iTeamRating
      const [iOmega, iDelta] = teamRatings
        .filter((_, q) => q !== i)
        .reduce(
          ([omega, delta], [qMu, qSigmaSq, _qTeam, qRank]) => {
            const ciq = Math.sqrt(iSigmaSq + qSigmaSq + TWOBETASQ)
            const piq = 1 / (1 + Math.exp((qMu - iMu) / ciq))
            const sigSqToCiq = iSigmaSq / ciq
            const iGamma = gamma(ciq, teamRatings.length, ...iTeamRating)
  
            return [
              omega + sigSqToCiq * (score(qRank, iRank) - piq),
              delta + ((iGamma * sigSqToCiq) / ciq) * piq * (1 - piq),
            ]
          },
          [0, 0]
        )
  
      return iTeam.map(({ mu, sigma }) => {
        const sigmaSq = sigma * sigma
        return {
          mu: mu + (sigmaSq / iSigmaSq) * iOmega,
          sigma:
            sigma *
            Math.sqrt(Math.max(1 - (sigmaSq / iSigmaSq) * iDelta, EPSILON)),
        }
      })
    })
  }
  