namespace Aeshnidae.Leaderboard;

public static class Commands
{
    [CommandHandler("top", AccessLevel.Player, CommandHandlerFlag.RequiresWorld, -1,
        "Leaderboards: who is highest, richest, deadliest and most enlightened.",
        "/top                     the boards, with who leads each\n" +
        "/top <board> [n]         the top n of one board (default 10)\n" +
        "/top me                  where you stand on every board\n" +
        "/top <board> me          where you stand on one\n" +
        "/top movers [board] [24h|7d] [n]   who gained most on a board over the last day or week\n" +
        "/top history <name> [board] [days]  a character's value day by day, from the snapshots")]
    public static void HandleTop(Session session, params string[] parameters)
    {
        var player = session.Player;

        if (player is null)
            return;

        if (!Db.Ready)
        {
            Reply(session, $"Leaderboards are unavailable: {Db.LastError}");
            return;
        }

        if (Boards.Snapshot.Count == 0)
        {
            Reply(session, "The boards are still being built - try again in a moment.");
            return;
        }

        if (parameters.Length == 0)
        {
            Overview(session);
            return;
        }

        var first = parameters[0].ToLowerInvariant();

        switch (first)
        {
            case "me":
                Me(session, player.Name);
                return;

            case "movers":
                Movers(session, parameters.Skip(1).ToArray(), player.Name);
                return;

            case "history":
                HistoryOf(session, parameters.Skip(1).ToArray());
                return;

            case "writehistory" when session.AccessLevel >= AccessLevel.Admin:
                History.WriteDailyFilesNow();
                Reply(session, $"Wrote {History.HistoryJsonPath} and today's file from the table.");
                return;

            case "refresh" when session.AccessLevel >= AccessLevel.Admin:
                Mod.RefreshNow();
                Reply(session, $"Refreshed: {Boards.CharacterCount} characters{(Boards.LastRefreshError.Length > 0 ? $" - {Boards.LastRefreshError}" : "")}.");
                return;

            case "post" when session.AccessLevel >= AccessLevel.Admin:
                Discord.PostNow();
                Reply(session, "Posting to Discord - /top hooks shows the result in a moment.");
                return;

            case "hooks" when session.AccessLevel >= AccessLevel.Admin:
                var sb = new StringBuilder();
                sb.AppendLine($"Last refresh {Boards.LastRefreshUtc:HH:mm:ss} UTC, {Boards.CharacterCount} characters. Discord: {Discord.LastResult}. Alerts: {Discord.LastAlertResult}.");
                sb.AppendLine($"History: last snapshot {(History.LastSnapshotUtc is { } snap ? snap.ToString("yyyy-MM-dd HH:mm") + " UTC" : "none")}, {History.Movers.Count} movers tables{(History.LastError.Length > 0 ? $", last error: {History.LastError}" : "")}.");
                foreach (var s in Hooks.Status)
                    sb.AppendLine($"  {(s.Bound ? "ok " : "-- ")} {s.Target}: {s.Note}");
                Reply(session, sb.ToString().TrimEnd());
                return;
        }

        // /top <board> [n | me]
        var count = Mod.Settings.Rows;
        var rest = parameters.ToList();
        var mine = false;

        if (rest.Count > 1 && rest[^1].Equals("me", StringComparison.OrdinalIgnoreCase))
        {
            mine = true;
            rest.RemoveAt(rest.Count - 1);
        }
        else if (rest.Count > 1 && int.TryParse(rest[^1], out var n))
        {
            count = Math.Clamp(n, 1, Mod.Settings.MaxRows);
            rest.RemoveAt(rest.Count - 1);
        }

        var board = Boards.Find(string.Join(" ", rest));

        if (board is null)
        {
            Reply(session, $"No board called '{string.Join(" ", rest)}'. Boards: {string.Join(", ", Boards.All.Select(b => b.Key))}.");
            return;
        }

        if (mine)
        {
            var pos = Boards.Position(board.Key, player.Name);
            Reply(session, pos is null
                ? $"{board.Title}: you are not on it yet."
                : $"{board.Title}: you are #{pos.Rank} of {Boards.Snapshot[board.Key].Count} with {pos.Value:N0} {board.Unit}{(pos.Extra.Length > 0 ? $" ({pos.Extra})" : "")}.");
            return;
        }

        ShowBoard(session, board, count, player.Name);
    }

    [CommandHandler("top-reload", AccessLevel.Admin, CommandHandlerFlag.None, 0,
        "Restart the Aeshnidae.Leaderboard mod, re-reading Settings.json.",
        "/top-reload")]
    public static void HandleReload(Session session, params string[] parameters)
    {
        var container = Mod.Container;

        if (container is null)
        {
            Reply(session, $"{Mod.Name} is not loaded.");
            return;
        }

        container.Restart();
        Reply(session, $"{Mod.Name} restarted.");
    }

    /// <summary>/top movers [board] [24h|7d] [n]: the movers of one board, or the leader of each.</summary>
    private static void Movers(Session session, string[] args, string self)
    {
        var window = "24h";
        var count = Mod.Settings.Rows;
        var rest = args.ToList();
        for (var i = rest.Count - 1; i >= 0; i--)
        {
            if (rest[i].Equals("24h", StringComparison.OrdinalIgnoreCase) || rest[i].Equals("7d", StringComparison.OrdinalIgnoreCase))
            {
                window = rest[i].ToLowerInvariant();
                rest.RemoveAt(i);
            }
            else if (int.TryParse(rest[i], out var n))
            {
                count = Math.Clamp(n, 1, Mod.Settings.MaxRows);
                rest.RemoveAt(i);
            }
        }

        if (History.Movers.Count == 0)
        {
            Reply(session, "No movers yet - the first snapshot is less than an hour old, or the history is off.");
            return;
        }

        var sb = new StringBuilder();
        if (rest.Count == 0)
        {
            sb.AppendLine($"Most gained in the last {window} - /top movers <board> {window} for the rest of a board:");
            foreach (var board in Boards.All)
            {
                var m = History.Find(board.Key, window);
                var top = m?.Rows.FirstOrDefault();
                sb.AppendLine(top is null
                    ? $"  {board.Key,-17} {board.Title}: nobody"
                    : $"  {board.Key,-17} {board.Title}: {top.Name} +{top.Delta:N0}");
            }
            Reply(session, sb.ToString().TrimEnd());
            return;
        }

        var wanted = Boards.Find(string.Join(" ", rest));
        if (wanted is null)
        {
            Reply(session, $"No board called '{string.Join(" ", rest)}'. Boards: {string.Join(", ", Boards.All.Select(b => b.Key))}.");
            return;
        }
        var movers = History.Find(wanted.Key, window);
        if (movers is null || movers.Rows.Count == 0)
        {
            Reply(session, $"{wanted.Title}: nobody gained anything in the last {window}.");
            return;
        }

        sb.AppendLine($"{wanted.Title} - most gained in the last {window} (since {movers.BaselineTakenUtc:d MMM HH:mm} UTC), top {Math.Min(count, movers.Rows.Count)} of {movers.Rows.Count}:");
        foreach (var row in movers.Rows.Take(count))
        {
            var you = row.Name.Equals(self, StringComparison.OrdinalIgnoreCase) ? "  <- you" : "";
            sb.AppendLine($"  {row.Rank,3}. {row.Name,-24} +{row.Delta,15:N0}  ({row.From:N0} -> {row.To:N0}){(row.IsNew ? "  new" : "")}{you}");
        }
        Reply(session, sb.ToString().TrimEnd());
    }

    /// <summary>/top history &lt;name&gt; [board] [days]: what the snapshots say a name had, day by day.</summary>
    private static void HistoryOf(Session session, string[] args)
    {
        var days = 14;
        var rest = args.ToList();
        if (rest.Count > 1 && int.TryParse(rest[^1], out var n))
        {
            days = Math.Clamp(n, 1, 400);
            rest.RemoveAt(rest.Count - 1);
        }
        if (rest.Count == 0)
        {
            Reply(session, "usage: /top history <name> [board] [days]");
            return;
        }

        // The name may be several words; a trailing board key is taken off it.
        Board? board = null;
        if (rest.Count > 1 && Boards.Find(rest[^1]) is { } found && found.Key.StartsWith(rest[^1].ToLowerInvariant().Replace(' ', '-')))
        {
            board = found;
            rest.RemoveAt(rest.Count - 1);
        }
        var name = string.Join(" ", rest);

        Dictionary<string, SortedDictionary<string, long>> daily;
        try { daily = Db.ReadDaily(name, days); }
        catch (Exception ex) { Reply(session, $"History unavailable: {ex.Message}"); return; }

        if (daily.Count == 0)
        {
            Reply(session, $"No snapshots have {name} on any board in the last {days} days.");
            return;
        }

        var sb = new StringBuilder();
        var boards = board is null ? Boards.All.Where(b => daily.ContainsKey(b.Key)).ToList() : new List<Board> { board };
        sb.AppendLine($"{name}, day by day (first snapshot of each UTC day), last {days} days:");
        foreach (var b in boards)
        {
            if (!daily.TryGetValue(b.Key, out var byDay) || byDay.Count == 0)
                continue;
            if (board is null)
            {
                // One line per board: the first and last day and the gain between them.
                var first = byDay.First();
                var last = byDay.Last();
                sb.AppendLine($"  {b.Title,-28} {first.Key} {first.Value,16:N0}  ->  {last.Key} {last.Value,16:N0}  (+{last.Value - first.Value:N0})");
                continue;
            }
            long? previous = null;
            foreach (var (day, value) in byDay)
            {
                sb.AppendLine($"  {day}  {value,16:N0}{(previous is { } p ? $"  {(value - p >= 0 ? "+" : "")}{value - p:N0}" : "")}");
                previous = value;
            }
        }
        if (board is null)
            sb.AppendLine("  /top history <name> <board> for every day of one board.");
        Reply(session, sb.ToString().TrimEnd());
    }

    private static void Overview(Session session)
    {
        var sb = new StringBuilder();
        sb.AppendLine($"Leaderboards - {Boards.CharacterCount} characters, refreshed {Ago(Boards.LastRefreshUtc)}. /top <board> for the top ten, /top me for yourself.");

        foreach (var board in Boards.All)
        {
            var leader = Boards.Snapshot.TryGetValue(board.Key, out var rows) && rows.Count > 0 ? rows[0] : null;
            sb.AppendLine(leader is null
                ? $"  {board.Key,-17} {board.Title}: nobody yet"
                : $"  {board.Key,-17} {board.Title}: {leader.Name}, {leader.Value:N0}");
        }

        Reply(session, sb.ToString().TrimEnd());
    }

    private static void ShowBoard(Session session, Board board, int count, string self)
    {
        var rows = Boards.Snapshot.TryGetValue(board.Key, out var list) ? list : new List<Row>();

        var sb = new StringBuilder();
        sb.AppendLine($"{board.Title} - top {Math.Min(count, rows.Count)} of {rows.Count}{(board.SinceInstall ? ", counted since 16 Sep 2026" : "")}{(board.PerAccount ? ", per account" : "")}:");

        if (rows.Count == 0)
            sb.AppendLine("  nobody yet.");

        foreach (var row in rows.Take(count))
        {
            var you = row.Name.Equals(self, StringComparison.OrdinalIgnoreCase) ? "  <- you" : "";
            sb.AppendLine($"  {row.Rank,3}. {row.Name,-24} {row.Value,16:N0}{(row.Extra.Length > 0 ? $"  {row.Extra}" : "")}{you}");
        }

        var mine = Boards.Position(board.Key, self);
        if (mine is not null && mine.Rank > count)
            sb.AppendLine($"  ...  you: #{mine.Rank} with {mine.Value:N0}");

        Reply(session, sb.ToString().TrimEnd());
    }

    private static void Me(Session session, string name)
    {
        var sb = new StringBuilder();
        sb.AppendLine($"{name} on the boards:");

        foreach (var board in Boards.All)
        {
            var pos = Boards.Position(board.Key, name);
            var total = Boards.Snapshot.TryGetValue(board.Key, out var rows) ? rows.Count : 0;
            sb.AppendLine(pos is null
                ? $"  {board.Title,-28} -"
                : $"  {board.Title,-28} #{pos.Rank} of {total}, {pos.Value:N0}");
        }

        Reply(session, sb.ToString().TrimEnd());
    }

    private static string Ago(DateTime utc)
    {
        if (utc == default) return "never";
        var span = DateTime.UtcNow - utc;
        return span.TotalMinutes < 1 ? "just now" : $"{span.TotalMinutes:N0} min ago";
    }

    private static void Reply(Session? session, string message)
    {
        if (session?.Player is null)
        {
            ModManager.Log(message);
            return;
        }

        foreach (var line in (message ?? "").Split('\n'))
        {
            var text = line.TrimEnd('\r');

            if (!string.IsNullOrWhiteSpace(text))
                session.Network.EnqueueSend(new GameMessageSystemChat(text, ChatMessageType.Broadcast));
        }
    }
}