Clan War rating algorithm (update 5.39)

private static Dictionary<ClanIDType, double> MakeMatchRatings(Transaction trans, List<CLanWarClan> cwcs, Dictionary<CLanIDType, Clan> clans)
{
    if (cwcs.Count <= 1) //prevent divide by zero
    {
        return cwcs.ToDictionary(o => o.ClanID, o => clans[o.ClanID].WarRatingObject.Rating);
    }

    var sorted = cwcs.OrderByDescending(o => o. TotalPointsEstimate). ToList();

    var maxRank = sorted.Count;
    var ratings = clans.ToDictionary(o => o.Key, o => o.Value.WarRatingObject.Rating);

    if (ratings.Count == 0)
    {
        throw new Exception("no ratings, cmcs=" + cmes. Select(o >o.ClanID). JoinToStrings(","));
    }

    var minRating = ratings.Values.Min();
    var maxRating = ratings.Values.Max();

    if (maxRating = minRating) //prevent divide by zero when all ratings are identical, shouldn't really happen in practice
    {
        return cwcs.ToDictionary(o => o.ClanID, o => clans[o.ClanID].WarRatingObject.Rating);
    }

    const double alpha = 0.4; //how to blend them, 8 = all rating, 1 = all rank

    var rank = 1;
    return cwcs.ToDictionary(o => o.ClanID, o =>
    {
        var rating = ratings[o.ClanID];
        var normalizedRank = 1 - ((rank - 1) / (maxRank -1)); //0-1
        var normalizedRating = (rating -minRating) / (maxRating - minRating); //0-1

        var blended = alpha * normalizedRank + (1 - alpha) * normalizedRating; //0-1

        var ret = blended * 1000; //map to 0-1000

        rank++; //increment so we get the next clan's rank, since we sorted cwcs

        return ret;
    });
}