using System.Text.Json;
using CounterStrikeSharp.API;
using CounterStrikeSharp.API.Modules.Cvars;
using CounterStrikeSharp.API.Modules.Timers;
using Microsoft.Extensions.Logging;
using Outnumbered.Domain;
using Outnumbered.Engine;

namespace Outnumbered;

// The local API: one Unix domain socket per instance (<SocketDir>/<ServerId>.sock). Three READ verbs —
//   status  : live server snapshot (map, counts, humans, mode extras), rebuilt on a ~2s game-thread timer
//   balance : the EFFECTIVE in-memory config (mode-resolved handicap) + dense neutral curves, rebuilt at load + !og_reload
//   top     : the three leaderboards, queried per request (repository methods are contractually off-thread, DB-only)
// — plus ONE operator verb, drain (announce + kick all humans so a pending SIGINT "shutdown when empty" completes
// cleanly; the deploy flow's kick-before-stop). The socket's 0660 file mode is the drain verb's entire access control:
// only the cs2 user (the site + the deploy scripts) can connect. The socket thread NEVER touches game state directly:
// reads serve pre-serialized byte[]; drain marshals through Server.NextFrame. Every payload carries V + GeneratedAtMs.
public sealed partial class OutnumberedPlugin
{
    private const int ApiSchemaVersion = 1;
    private const float StatusRebuildSeconds = 2.0f;
    private const int ApiTopN = 50;
    private const int CurveSteps = 200; // t = -1..+1 inclusive -> 201 samples at 0.01

    private UdsServer? _api;
    private CounterStrikeSharp.API.Modules.Timers.Timer? _statusTimer;
    private volatile byte[] _statusJson = ApiErr("not-ready");  // served until the first game-thread rebuild lands
    private volatile byte[] _balanceJson = ApiErr("not-ready");
    private bool _engineReady;      // set once SetupMap has run — engine statics (Server.MapName etc.) crash before that
    private bool _apiErrLogged;     // one socket-error log line per load, not one per request
    private string _apiServerId = "";
    private int _apiPort;

    private static byte[] ApiErr(string code) => JsonSerializer.SerializeToUtf8Bytes(new { Err = code });

    private void Initialize_Api()
    {
        if (!Config.Api.Enabled) return;
        _apiServerId = ServerId();
        var args = CommandLineArgs(); // same -port -> +hostport fallback chain ServerId() resolves with
        _apiPort = int.TryParse(ArgValue(args, "port") ?? ArgValue(args, "hostport"), out int port) ? port : 0;
        RebuildBalancePayload(); // config + domain math only — engine-safe at Load

        string path = Path.Combine(Config.Api.SocketDir, _apiServerId + ".sock");
        try
        {
            _api = new UdsServer(path, HandleApiRequest, ex =>
            {
                if (_apiErrLogged) return;
                _apiErrLogged = true;
                Logger.LogWarning(ex, "Outnumbered API socket error (further ones suppressed this load)");
            });
        }
        catch (Exception ex)
        {
            // Missing/unwritable socket dir (dev box without the tmpfiles.d entry) — the API is optional, the game isn't.
            Logger.LogWarning(ex, "Outnumbered API disabled: cannot bind {Path}", path);
            return;
        }
        _statusTimer = AddTimer(StatusRebuildSeconds, RebuildStatusPayload, TimerFlags.REPEAT);
        Logger.LogInformation("Outnumbered API listening on {Path}", path);
    }

    private void Shutdown_Api()
    {
        _statusTimer?.Kill();
        _api?.Dispose(); // closes the listener + unlinks the socket file, so a hot-reload can re-bind
        _api = null;
    }

    // Socket-thread dispatch: cached bytes for status/balance; top is the one per-request worker (DB-only).
    private Task<byte[]> HandleApiRequest(string verb) => verb switch
    {
        "status" => Task.FromResult(_statusJson),
        "balance" => Task.FromResult(_balanceJson),
        "top" => BuildTopPayload(),
        "drain" => Drain(),
        _ => Task.FromResult(ApiErr("unknown-verb")),
    };

    private const float DrainKickDelaySeconds = 5.0f; // long enough to read the announce, short enough for a deploy

    // Deploy-flow kick: announce, then kick every human, so the engine's SIGINT "shutdown when empty" completes with a
    // CLEAN plugin unload (persistence flush) instead of the stop timeout's SIGKILL. Bots don't block shutdown.
    // Replies immediately; the caller sleeps past the delay before systemctl stop.
    private Task<byte[]> Drain()
    {
        Server.NextFrame(() =>
        {
            if (!_live) return;
            Server.PrintToChatAll(" [Outnumbered] Server is restarting for an update — reconnect in a minute!");
            AddTimer(DrainKickDelaySeconds, () =>
            {
                if (!_live) return;
                foreach (var p in Utilities.GetPlayers())
                    if (IsHuman(p) && p.UserId is { } uid)
                        Server.ExecuteCommand($"kickid {uid} \"Server updating - back in a minute!\"");
            });
        });
        return Task.FromResult(JsonSerializer.SerializeToUtf8Bytes(new { Ok = true, KickInSeconds = (int)DrainKickDelaySeconds }));
    }

    // Game-thread timer (~2s): mirrors the HUD gather (materialized roster -> IsHuman -> _players). Allocation per
    // rebuild is fine at this cadence. Per-player handicap bands are deliberately NOT exposed.
    private void RebuildStatusPayload()
    {
        if (!_engineReady) return; // pre-first-map: keep serving not-ready instead of crashing on engine statics
        var players = Utilities.GetPlayers();
        var humans = new List<object>(players.Count);
        int bots = 0;
        foreach (var p in players)
        {
            if (IsBot(p)) { bots++; continue; }
            if (!IsHuman(p)) continue;
            var sid = p.AuthorizedSteamID?.SteamId64;
            if (sid is null || !_players.TryGetValue(sid.Value, out var pd)) continue;
            humans.Add(new
            {
                pd.Name,
                pd.Level,
                pd.Prestige,
                pd.Kills,
                pd.Deaths,
                pd.Streak,
                Rung = pd.GgRung, // site maps Rung -> weapon via the GG StatusExtra ladder; harmless zero in other modes
            });
        }
        _statusJson = JsonSerializer.SerializeToUtf8Bytes(new
        {
            V = ApiSchemaVersion,
            GeneratedAtMs = DateTimeOffset.UtcNow.ToUnixTimeMilliseconds(),
            ServerId = _apiServerId,
            Mode = _driver.Id,
            Map = Server.MapName,
            Hostname = ConVar.Find("hostname")?.StringValue ?? "",
            Port = _apiPort,
            MaxHumans = _driver.MaxHumansOnCt,
            Bots = bots,
            Humans = humans,
            Extra = _driver.StatusExtra(),
        });
    }

    // The effective balance: the LIVE Config (post-!og_reload) with the mode-resolved handicap, plus neutral curves
    // sampled through the same compiled HandicapModel code that scales damage. EXPLICIT allowlist of blocks — never
    // the root Config (Database carries credentials). Called at Initialize_Api and from Cmd_ReloadConfig.
    internal void RebuildBalancePayload()
    {
        // Guarded end-to-end: pathological config (e.g. Curve <= 0 -> Pow(0, neg) = Infinity -> the serializer throws
        // on non-finite doubles) must degrade the API verb, never the plugin — the live damage path tolerates the same
        // config without throwing, and this runs unguarded inside Load.
        try
        {
            _balanceJson = BuildBalanceJson();
        }
        catch (Exception ex)
        {
            Logger.LogWarning(ex, "Outnumbered API balance payload rebuild failed — serving 'balance-unavailable'");
            _balanceJson = ApiErr("balance-unavailable");
        }
    }

    private byte[] BuildBalanceJson()
    {
        var t = new double[CurveSteps + 1];
        var deal = new double[CurveSteps + 1];
        var take = new double[CurveSteps + 1];
        var xp = new double[CurveSteps + 1];
        for (int i = 0; i <= CurveSteps; i++)
        {
            t[i] = -1.0 + i * (2.0 / CurveSteps);
            HandicapModel.BandsFromT(t[i], _hcap, out deal[i], out take[i], out xp[i]);
        }
        return JsonSerializer.SerializeToUtf8Bytes(new
        {
            V = ApiSchemaVersion,
            GeneratedAtMs = DateTimeOffset.UtcNow.ToUnixTimeMilliseconds(),
            ServerId = _apiServerId,
            Mode = _driver?.Id ?? Config.Mode, // driver not yet selected only if called before Initialize_Driver
            Match = Config.Match,
            Stats = Config.Stats,
            Progression = Config.Progression,
            Abilities = Config.Abilities,
            GunGame = Config.GunGame,
            Survival = Config.Survival,
            EffectiveHandicap = _hcap.Config,
            Curves = new { T = t, Deal = deal, Take = take, Xp = xp },
        });
    }

    // Socket thread: repository calls only (no game objects), mirroring the Cmd_Top precedent. A failure (boot race
    // with the fire-and-forget EnsureSchema, DB down) degrades to an err payload — the site renders last-good.
    private async Task<byte[]> BuildTopPayload()
    {
        try
        {
            var levels = await _repo.GetTopAsync(ApiTopN);
            var waves = await _repo.GetTopWavesAsync(ApiTopN);
            var ggTimes = await _repo.GetTopGgAsync(ApiTopN);
            return JsonSerializer.SerializeToUtf8Bytes(new
            {
                V = ApiSchemaVersion,
                GeneratedAtMs = DateTimeOffset.UtcNow.ToUnixTimeMilliseconds(),
                Levels = levels,
                Waves = waves,
                GgTimes = ggTimes,
            });
        }
        catch (Exception ex)
        {
            if (!_apiErrLogged) { _apiErrLogged = true; Logger.LogWarning(ex, "Outnumbered API top query failed"); }
            return ApiErr("db");
        }
    }
}