namespace FozFc.Api.Domain;

/// <summary>
/// Fan-rank tiers and XP model (mirrors the values previously used client-side).
/// </summary>
public static class FanRank
{
    public const int XpPerEuroSpent = 10;
    public const int XpPerMembershipMonth = 120;

    public sealed record Tier(string Rank, int MinXp);

    public static readonly IReadOnlyList<Tier> Tiers = new List<Tier>
    {
        new("Copper", 0),
        new("Bronze", 600),
        new("Silver", 1800),
        new("Gold", 4200),
        new("Platinium", 7800),
        new("Diamond", 12500),
    };

    public sealed record RankProgress(string FanRank, string? NextRank, int XpToNextRank, int XpProgressPercent);

    public static RankProgress Compute(int xp)
    {
        var safeXp = Math.Max(0, xp);
        Tier current = Tiers[0];
        Tier? next = null;

        for (var i = 0; i < Tiers.Count; i++)
        {
            var upcoming = i + 1 < Tiers.Count ? Tiers[i + 1] : null;
            if (safeXp >= Tiers[i].MinXp)
            {
                current = Tiers[i];
                next = upcoming;
            }
        }

        if (next is null)
        {
            return new RankProgress(current.Rank, null, 0, 100);
        }

        var range = Math.Max(1, next.MinXp - current.MinXp);
        var within = Math.Max(0, safeXp - current.MinXp);
        var percent = Math.Clamp((int)Math.Round((double)within / range * 100), 0, 100);
        return new RankProgress(current.Rank, next.Rank, Math.Max(0, next.MinXp - safeXp), percent);
    }
}