HokmPlay/server/src/Hokm.Server/Profiles/Gamification.cs

namespace Hokm.Server.Profiles;

/// <summary>Server-side port of src/lib/online/gamification.ts.</summary>
public static class Gamification
{
    private static readonly (string id, int floor)[] Tiers =
        { ("bronze", 0), ("silver", 1100), ("gold", 1300), ("platinum", 1500), ("diamond", 1700), ("master", 1900) };

    private static int RankValue(int rating)
    {
        int idx = 0;
        for (int i = 0; i < Tiers.Length; i++) if (rating >= Tiers[i].floor) idx = i;
        if (idx == Tiers.Length - 1) return idx * 10;
        double floor = Tiers[idx].floor, next = Tiers[idx + 1].floor, third = (next - floor) / 3.0;
        double within = rating - floor;
        int division = within < third ? 3 : within < 2 * third ? 2 : 1;
        return idx * 10 - division;
    }

    private const int K = 32;

    public static int RatingDelta(MatchSummaryDto s, int my, int opp)
    {
        if (!s.Ranked) return 0;
        double expected = 1.0 / (1.0 + Math.Pow(10, (opp - my) / 400.0));
        double delta = K * ((s.Won ? 1 : 0) - expected);
        if (s.Won && s.KotFor) delta += 8;
        if (!s.Won && s.KotAgainst) delta -= 8;
        int r = (int)Math.Round(delta);
        return s.Won ? Math.Max(1, r) : Math.Min(-1, r);
    }

    public static int CoinDelta(MatchSummaryDto s)
    {
        if (!s.Ranked) return 0;
        int kot = s.Won && s.KotFor ? 40 : 0;
        return (s.Won ? s.Stake : -s.Stake) + kot;
    }

    public static int XpForLevel(int level) => 100 * level;
    public static int MatchXp(MatchSummaryDto s) =>
        40 + (s.Won ? 80 : 0) + s.TricksWon * 5 + (s.KotFor ? 30 : 0);

    private record AchDef(string Id, string NameFa, string NameEn, string Icon, int Goal, int Coin);
    private static readonly AchDef[] Achs =
    {
        new("first_win", "اولین برد", "First Win", "🥇", 1, 100),
        new("first_kot", "اولین کُت", "First Kot", "🔥", 1, 150),
        new("wins_10", "۱۰ برد", "10 Wins", "🎯", 10, 300),
        new("wins_100", "۱۰۰ برد", "100 Wins", "👑", 100, 2000),
        new("streak_5", "نوار ۵ برد", "5 Win Streak", "⚡", 5, 400),
        new("reach_gold", "رسیدن به طلا", "Reach Gold", "🏅", 1, 500),
        new("games_50", "۵۰ بازی", "50 Games", "🎮", 50, 350),
    };

    private static int AchProgress(string id, StatsDto st, int rating) => id switch
    {
        "first_win" => Math.Min(1, st.Wins),
        "first_kot" => Math.Min(1, st.KotsFor),
        "wins_10" => Math.Min(10, st.Wins),
        "wins_100" => Math.Min(100, st.Wins),
        "streak_5" => Math.Min(5, st.BestWinStreak),
        "reach_gold" => rating >= 1300 ? 1 : 0,
        "games_50" => Math.Min(50, st.Games),
        _ => 0,
    };

    private record TitleDef(string Id, string NameFa, string NameEn);
    private static readonly TitleDef[] Titles =
    {
        new("novice", "تازه‌کار", "Novice"), new("winner", "برنده", "Winner"),
        new("kot_master", "استاد کُت", "Kot Master"), new("veteran", "کهنه‌کار", "Veteran"),
        new("champion", "قهرمان", "Champion"), new("legend", "اسطوره", "Legend"),
    };

    private static bool TitleUnlocked(string id, StatsDto st, int rating, int level) => id switch
    {
        "novice" => true,
        "winner" => st.Wins >= 10,
        "kot_master" => st.KotsFor >= 10,
        "veteran" => level >= 20,
        "champion" => rating >= 1300,
        "legend" => rating >= 1900,
        _ => false,
    };

    private static (int level, int xp, bool up) AddXp(int level, int xp, int gain)
    {
        bool up = false;
        xp += gain;
        while (xp >= XpForLevel(level)) { xp -= XpForLevel(level); level++; up = true; }
        return (level, xp, up);
    }

    /// <summary>Applies a finished match to the profile (mutates it) and returns the reward breakdown.</summary>
    public static RewardResultDto ApplyMatch(ProfileDto p, MatchSummaryDto s, int oppRating)
    {
        int ratingBefore = p.Rating, coinsBefore = p.Coins, levelBefore = p.Level;
        int rDelta = RatingDelta(s, p.Rating, oppRating);
        int ratingAfter = Math.Max(0, ratingBefore + rDelta);
        int cDelta = CoinDelta(s);
        var lvl = AddXp(p.Level, p.Xp, MatchXp(s));

        var st = p.Stats;
        int cur = s.Won ? st.CurrentWinStreak + 1 : 0;
        st.Games += 1;
        st.Wins += s.Won ? 1 : 0;
        st.Losses += s.Won ? 0 : 1;
        st.KotsFor += s.KotFor ? 1 : 0;
        st.KotsAgainst += s.KotAgainst ? 1 : 0;
        st.Tricks += s.TricksWon;
        st.CurrentWinStreak = cur;
        st.BestWinStreak = Math.Max(st.BestWinStreak, cur);

        var newAch = new List<AchievementUnlockDto>();
        int achCoins = 0;
        foreach (var d in Achs)
        {
            int prog = AchProgress(d.Id, st, ratingAfter);
            p.Achievements[d.Id] = prog;
            if (prog >= d.Goal && !p.Unlocked.Contains(d.Id))
            {
                p.Unlocked.Add(d.Id);
                achCoins += d.Coin;
                newAch.Add(new() { Id = d.Id, NameFa = d.NameFa, NameEn = d.NameEn, Icon = d.Icon, CoinReward = d.Coin });
            }
        }
        int coinsAfter = Math.Max(0, coinsBefore + cDelta + achCoins);

        var newTitles = new List<TitleUnlockDto>();
        foreach (var td in Titles)
            if (TitleUnlocked(td.Id, st, ratingAfter, lvl.level) && !p.OwnedTitles.Contains(td.Id))
            {
                p.OwnedTitles.Add(td.Id);
                newTitles.Add(new() { Id = td.Id, NameFa = td.NameFa, NameEn = td.NameEn });
            }

        bool promoted = RankValue(ratingAfter) > RankValue(ratingBefore);
        bool demoted = RankValue(ratingAfter) < RankValue(ratingBefore);

        p.Rating = ratingAfter;
        p.Coins = coinsAfter;
        p.Level = lvl.level;
        p.Xp = lvl.xp;

        return new RewardResultDto
        {
            RatingBefore = ratingBefore,
            RatingAfter = ratingAfter,
            RatingDelta = ratingAfter - ratingBefore,
            CoinsBefore = coinsBefore,
            CoinsAfter = coinsAfter,
            CoinsDelta = coinsAfter - coinsBefore,
            XpGained = MatchXp(s),
            LevelBefore = levelBefore,
            LevelAfter = lvl.level,
            LeveledUp = lvl.level > levelBefore,
            NewAchievements = newAch,
            NewTitles = newTitles,
            Promoted = promoted,
            Demoted = demoted,
        };
    }
}