Create rating systems

createSystems.ts

const symmetricRatingSystem = createRatingSystem()

const playerKFactor = 32
const questionKFactor = 4
const asymmetricKFactorFn: KFactorFunctionWithPlayers = (rating, playerIndex) => {
    let kFactor = playerIndex === 0
        ? playerKFactor
        : questionKFactor

    if (rating > 6000) {
        kFactor = Math.ceil(kFactor / 2)
    }
    else if (rating > 4000) {
        kFactor = Math.ceil(kFactor / 1.5)
    }

    return kFactor
}

const asymmetricRatingSystem = createRatingSystem(asymmetricKFactorFn)