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;
        // Kot bonus scales with the league stake (mirrors gamification.ts).
        int kot = s.Won && s.KotFor ? (int)Math.Round(s.Stake * 0.4) : 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);

    // metric: wins|kotsFor|bestWinStreak|shutoutWins|games|tricks|level ; ratingFloor>0 = rank ach.
    private record AchDef(string Id, string? Metric, int RatingFloor, int Goal, int Coin, string NameFa, string NameEn, string Icon);
    // Mirrors src/lib/online/gamification.ts (same ids/goals/coins/metrics).
    private static int Coin(int g) => Math.Max(100, (int)Math.Floor((80.0 + g * 12) / 50.0 + 0.5) * 50);
    private static string Fa(int n) =>
        new string(n.ToString().Select(c => c is >= '0' and <= '9' ? "۰۱۲۳۴۵۶۷۸۹"[c - '0'] : c).ToArray());

    private static AchDef[] Tier(string metric, string prefix, string icon, int[] goals, Func<int, string> faName, Func<int, string> enName)
        => goals.Select(g => new AchDef($"{prefix}_{g}", metric, 0, g, Coin(g), faName(g), enName(g), icon)).ToArray();

    private static readonly AchDef[] Achs = BuildAchs();
    private static AchDef[] BuildAchs()
    {
        var l = new List<AchDef>();
        l.AddRange(Tier("wins", "wins", "🏆", new[] { 1, 5, 10, 25, 50, 75, 100, 150, 200, 250, 300, 400, 500, 750, 1000, 2000 }, g => $"{Fa(g)} برد", g => $"{g} Wins"));
        l.AddRange(Tier("shutoutWins", "shutout", "🧹", new[] { 1, 3, 5, 10, 25, 50, 100 }, g => $"{Fa(g)} بار هفت–هیچ", g => $"{g}× Sweep"));
        l.AddRange(Tier("kotsFor", "kot", "🔥", new[] { 1, 3, 5, 10, 25, 50, 75, 100, 150, 200, 300, 500 }, g => $"{Fa(g)} کُت", g => $"{g} Kots"));
        l.AddRange(Tier("bestWinStreak", "streak", "⚡", new[] { 2, 3, 5, 7, 10, 15, 20, 25, 30, 40 }, g => $"{Fa(g)} برد پیاپی", g => $"{g} Win Streak"));
        l.AddRange(Tier("hakemRounds", "hakem", "👑", new[] { 7, 25, 50, 100, 250, 500, 1000 }, g => $"{Fa(g)} بار حاکم", g => $"Hakem {g}×"));
        l.AddRange(Tier("level", "level", "⭐", new[] { 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 60, 70, 80, 90, 100 }, g => $"سطح {Fa(g)}", g => $"Level {g}"));
        l.AddRange(Tier("games", "games", "🎮", new[] { 10, 25, 50, 100, 200, 300, 500, 750, 1000, 2000, 5000 }, g => $"{Fa(g)} بازی", g => $"{g} Games"));
        l.AddRange(Tier("roundsWon", "rounds", "🎴", new[] { 25, 100, 250, 500, 1000, 2000, 5000 }, g => $"{Fa(g)} دست برده", g => $"{g} Rounds Won"));
        l.AddRange(Tier("tricks", "tricks", "🗂️", new[] { 50, 100, 250, 500, 1000, 2500, 5000, 10000 }, g => $"{Fa(g)} دست‌برد", g => $"{g} Tricks"));
        l.AddRange(Tier("losses", "grit", "🛡️", new[] { 10, 50, 100 }, g => $"{Fa(g)} باخت", g => $"{g} Losses"));
        l.Add(new AchDef("reach_silver", null, 1100, 1, 200, "لیگ نقره", "Reach Silver", "🥈"));
        l.Add(new AchDef("reach_gold", null, 1300, 1, 500, "لیگ طلا", "Reach Gold", "🥇"));
        l.Add(new AchDef("reach_platinum", null, 1500, 1, 1000, "لیگ پلاتین", "Reach Platinum", "🛡️"));
        l.Add(new AchDef("reach_diamond", null, 1700, 1, 2000, "لیگ الماس", "Reach Diamond", "💠"));
        l.Add(new AchDef("reach_master", null, 1900, 1, 4000, "لیگ استاد", "Reach Master", "👑"));
        return l.ToArray();
    }

    private static int Metric(string m, StatsDto st, int level) => m switch
    {
        "wins" => st.Wins,
        "losses" => st.Losses,
        "kotsFor" => st.KotsFor,
        "bestWinStreak" => st.BestWinStreak,
        "shutoutWins" => st.ShutoutWins,
        "games" => st.Games,
        "tricks" => st.Tricks,
        "hakemRounds" => st.HakemRounds,
        "roundsWon" => st.RoundsWon,
        "level" => level,
        _ => 0,
    };

    private static int AchProgress(AchDef d, StatsDto st, int rating, int level)
    {
        if (d.RatingFloor > 0) return rating >= d.RatingFloor ? d.Goal : 0;
        if (d.Metric == null) return 0;
        return Math.Min(d.Goal, Metric(d.Metric, st, level));
    }

    private record TitleDef(string Id, string NameFa, string NameEn);
    private static readonly TitleDef[] Titles =
    {
        new("novice", "تازه‌کار", "Novice"), new("winner", "برنده", "Winner"),
        new("expert", "خبره", "Expert"), new("kot_master", "استاد کُت", "Kot Master"),
        new("professional", "حرفه‌ای", "Professional"), new("veteran", "کهنه‌کار", "Veteran"),
        new("captain", "کاپیتان", "Captain"), new("champion", "قهرمان", "Champion"),
        new("leader", "فرمانده", "Leader"), new("legend", "اسطوره", "Legend"),
    };

    private static bool TitleUnlocked(string id, StatsDto st, int rating, int level) => id switch
    {
        "novice" => true,
        "winner" => st.Wins >= 10,
        "expert" => level >= 25,
        "kot_master" => st.KotsFor >= 25,
        "professional" => st.Wins >= 50,
        "veteran" => level >= 30,
        "captain" => st.Wins >= 100,
        "champion" => rating >= 1300,
        "leader" => st.Wins >= 250,
        "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);
        st.ShutoutWins += s.Won && s.Shutout ? 1 : 0;
        st.HakemRounds += s.HakemRounds;
        st.RoundsWon += s.RoundsWon;

        var newAch = new List<AchievementUnlockDto>();
        int achCoins = 0;
        foreach (var d in Achs)
        {
            int prog = AchProgress(d, st, ratingAfter, lvl.level);
            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,
        };
    }
}