using System.Text.Json;
using CounterStrikeSharp.API;
using CounterStrikeSharp.API.Core;
using CounterStrikeSharp.API.Core.Attributes.Registration;
using CounterStrikeSharp.API.Core.Capabilities;
using CounterStrikeSharp.API.Modules.Admin;
using CounterStrikeSharp.API.Modules.Commands;
using CounterStrikeSharp.API.Modules.Entities;
using CounterStrikeSharp.API.Modules.Timers;
using CounterStrikeSharp.API.Modules.UserMessages;
using CounterStrikeSharp.API.Modules.Utils;
using CounterStrikeSharp.API.ValveConstants.Protobuf;
using CS2_SimpleAdminApi;
using Microsoft.Extensions.Logging;

namespace AdminStealth;

// Companion to CS2-SimpleAdmin's css_hide. When an admin hides, everyone else sees them leave the
// server, and nothing the hide does afterwards (the suicide, the team changes, their real
// disconnect later) is announced. Hidden admins stay hidden across reconnects and map changes, and
// can't join a team until they unhide. Also blocks the status command for players, which would
// otherwise still list a hidden admin.
public class AdminStealth : BasePlugin
{
    public override string ModuleName => "AdminStealth";
    public override string ModuleVersion => "0.3.15";
    public override string ModuleAuthor => "astra";
    public override string ModuleDescription => "Makes CS2-SimpleAdmin's css_hide look like leaving, and keeps it";

    // css_hide's own permission, unless admin_overrides.json overrides css_hide (see CanHide).
    // Restoring waits for it, since SimpleAdmin loads admins after connect.
    private const string HidePermission = "@css/kick";
    private const float RestoreDelay = 2f;
    private const int RestoreAttempts = 5;
    // How soon after connecting a hidden admin is moved to spectators, past the team select screen.
    private const float SkipTeamSelectDelay = 0.1f;
    // CS_UM_VGUIMenu: how the server opens the team select screen, as name "team". CS2 opens it
    // whatever the message's "show" says (the server doesn't even set it), so it can't close one.
    private const int VguiMenuMessage = 301;

    private static readonly PluginCapability<ICS2_SimpleAdminApi> SimpleAdminCapability = new("simpleadmin:api");
    private ICS2_SimpleAdminApi? _simpleAdmin;

    // SteamID64s of admins who hid and haven't unhidden, kept in hidden.json.
    private readonly HashSet<ulong> _hidden = [];
    private string[] _hideAliases = ["css_hide", "css_stealth"];

    // Slot -> tick a hide alias was typed, to tell an admin unhiding themselves from SimpleAdmin
    // unhiding them because they joined a team.
    private readonly Dictionary<int, int> _hideTyped = [];
    // Slots with a restore timer running, and slots whose hide was run by us rather than typed.
    private readonly HashSet<int> _restoreScheduled = [];
    private readonly HashSet<int> _restoring = [];

    private static string ConfigDirectory => Path.Combine(Server.GameDirectory, "csgo", "addons", "counterstrikesharp",
        "configs", "plugins");

    private static string HiddenPath => Path.Combine(ConfigDirectory, "AdminStealth", "hidden.json");

    public override void Load(bool hotReload)
    {
        LoadHidden();
        _hideAliases = ReadHideAliases();
        // Each listener needs its own delegate: CSS keys a plugin's listeners by handler, so adding
        // the same method twice orphans the first registration, which then blocks its command
        // without ever calling us.
        foreach (var alias in _hideAliases)
            AddCommandListener(alias, (player, command) => OnHideTyped(player, command));
        // Players who may not hide get no reply at all, not even CSS's missing-permission one. Only
        // a catch-all listener runs before every plugin's command handler, for console and chat.
        AddCommandListener(null, OnAnyCommand);
        // Joining any team, spectators included, would make SimpleAdmin unhide them.
        AddCommandListener("jointeam", (player, command) => OnJoinTeam(player, command));
        AddCommandListener("spectate", (player, command) => OnJoinTeam(player, command));
        // M. Hidden admins have no team, and the game won't let a player with no team close the
        // team screen without picking one, so don't let it open.
        AddCommandListener("teammenu", OnTeamMenu);
        AddCommandListener("status", OnStatus);
        HookUserMessage(VguiMenuMessage, OnVguiMenu);

        RegisterListener<Listeners.OnMapStart>(_ =>
        {
            _hideTyped.Clear();
            _restoreScheduled.Clear();
            _restoring.Clear();
            _closingTeamScreen.Clear();
        });
    }

    public override void OnAllPluginsLoaded(bool hotReload)
    {
        try
        {
            _simpleAdmin = SimpleAdminCapability.Get();
        }
        catch (KeyNotFoundException)
        {
        }

        if (_simpleAdmin == null)
        {
            Logger.LogError("CS2-SimpleAdmin's API isn't available, so hiding won't look like leaving or last");
            return;
        }
        _simpleAdmin.OnAdminToggleSilent += OnAdminToggleSilent;

        if (hotReload)
        {
            foreach (var player in Utilities.GetPlayers())
            {
                if (player is { IsValid: true, IsBot: false } && _hidden.Contains(player.SteamID))
                    ScheduleRestore(player, RestoreDelay);
            }
        }
    }

    public override void Unload(bool hotReload)
    {
        if (_simpleAdmin != null)
            _simpleAdmin.OnAdminToggleSilent -= OnAdminToggleSilent;
    }

    // Players get nothing back. The server console and RCON still work.
    private HookResult OnStatus(CCSPlayerController? player, CommandInfo command)
    {
        return player == null ? HookResult.Continue : HookResult.Stop;
    }

    private HookResult OnAnyCommand(CCSPlayerController? player, CommandInfo command)
    {
        if (player is not { IsValid: true, IsBot: false } ||
            !_hideAliases.Contains(command.GetArg(0), StringComparer.OrdinalIgnoreCase) || CanHide(player))
            return HookResult.Continue;
        return HookResult.Stop;
    }

    private HookResult OnHideTyped(CCSPlayerController? player, CommandInfo command)
    {
        if (player is { IsValid: true } && !_restoring.Contains(player.Slot))
            _hideTyped[player.Slot] = Server.TickCount;
        return HookResult.Continue;
    }

    private HookResult OnJoinTeam(CCSPlayerController? player, CommandInfo command)
    {
        if (!IsHidden(player))
            return HookResult.Continue;

        player!.PrintToChat($" You're hidden, so you can't join a team. Type {ChatAlias()} to show yourself.");

        CloseTeamScreen(player);
        return HookResult.Stop;
    }

    // M opens the team screen on the client, where the server can't block it, and a player with no
    // team (as hidden admins are) can't close it without picking. Telling only their client they
    // joined spectators doesn't close it (tried live), so do what css_hide does: really move them
    // to spectators and back to no team, with the team screen disabled around it. Their team
    // events aren't broadcast while hidden (OnPlayerTeam), and our SimpleAdmin fork doesn't unhide
    // for spectators.
    private readonly HashSet<int> _closingTeamScreen = [];

    private void CloseTeamScreen(CCSPlayerController player)
    {
        var slot = player.Slot;
        if (!_closingTeamScreen.Add(slot))
            return;

        Server.ExecuteCommand("sv_disable_teamselect_menu 1");
        Server.NextFrame(() =>
        {
            var p = Utilities.GetPlayerFromSlot(slot);
            if (p is { IsValid: true } && IsHidden(p) && p.TeamNum == (byte)CsTeam.None)
                p.ChangeTeam(CsTeam.Spectator);
        });
        AddTimer(0.15f, () =>
        {
            var p = Utilities.GetPlayerFromSlot(slot);
            if (p is { IsValid: true } && IsHidden(p) && p.TeamNum == (byte)CsTeam.Spectator)
                p.ChangeTeam(CsTeam.None);
        }, TimerFlags.STOP_ON_MAPCHANGE);
        AddTimer(0.5f, () =>
        {
            _closingTeamScreen.Remove(slot);
            Server.ExecuteCommand("sv_disable_teamselect_menu 0");
        }, TimerFlags.STOP_ON_MAPCHANGE);
    }

    private HookResult OnTeamMenu(CCSPlayerController? player, CommandInfo command)
    {
        if (!IsHidden(player))
            return HookResult.Continue;

        Logger.LogInformation("Blocked teammenu from hidden admin {Name}", player!.PlayerName);
        player.PrintToChat($" You're hidden, so you can't join a team. Type {ChatAlias()} to show yourself.");
        return HookResult.Stop;
    }

    // Keeps the team select screen from ever opening for a hidden admin.
    private HookResult OnVguiMenu(UserMessage message)
    {
        try
        {
            if (message.ReadString("name") != "team")
                return HookResult.Continue;
        }
        catch (Exception ex)
        {
            WarnMenuOnce($"Couldn't read the team menu message ({message.DebugString}): {ex.Message}");
            return HookResult.Continue;
        }

        foreach (var player in message.Recipients.ToList())
        {
            if (!IsHidden(player))
                continue;
            message.Recipients.Remove(player);
            Logger.LogInformation("Kept the team menu from hidden admin {Name}", player.PlayerName);
        }
        return HookResult.Continue;
    }

    private bool _menuWarned;

    private void WarnMenuOnce(string warning)
    {
        if (_menuWarned)
            return;
        _menuWarned = true;
        Logger.LogWarning("{Warning}", warning);
    }

    private void OnAdminToggleSilent(int slot, bool hidden)
    {
        // The typed command's listener may run before or after SimpleAdmin's handler, which fires
        // this, so decide on the next frame, once both have run.
        var tick = Server.TickCount;
        Server.NextFrame(() => ResolveToggle(slot, hidden, tick));
    }

    private void ResolveToggle(int slot, bool hidden, int tick)
    {
        var typed = _hideTyped.Remove(slot, out var typedTick) && typedTick == tick;

        var admin = Utilities.GetPlayerFromSlot(slot);
        if (admin is not { IsValid: true, IsBot: false })
            return;

        if (hidden)
        {
            if (_restoring.Remove(slot))
            {
                admin.PrintToChat($" You're still hidden. Type {ChatAlias()} to show yourself.");
                return;
            }
            if (_hidden.Add(admin.SteamID))
                SaveHidden();
            SendFakeLeave(admin);
            return;
        }

        if (typed)
        {
            if (_hidden.Remove(admin.SteamID))
                SaveHidden();
        }
        else if (_hidden.Contains(admin.SteamID))
        {
            // SimpleAdmin unhides anyone who joins a team, e.g. when the game auto-assigns them.
            ScheduleRestore(admin, 0.1f);
        }
    }

    // A fake player_disconnect, sent to each client rather than fired on the server, so no plugin
    // (SimpleAdmin included) treats the admin as really gone.
    private static void SendFakeLeave(CCSPlayerController admin)
    {
        var leave = new EventPlayerDisconnect(true)
        {
            Userid = admin,
            Playerid = admin.Slot,
            Name = admin.PlayerName,
            Networkid = new SteamID(admin.SteamID).SteamId3,
            Xuid = admin.SteamID,
            Reason = (int)NetworkDisconnectionReason.NETWORK_DISCONNECT_DISCONNECT_BY_USER,
            EverFullyConnected = true,
        };
        foreach (var player in Utilities.GetPlayers())
        {
            if (player is { IsValid: true, IsBot: false, IsHLTV: false } && player.Slot != admin.Slot)
                leave.FireEventToClient(player);
        }
        leave.Free();
    }

    private void ScheduleRestore(CCSPlayerController player, float delay)
    {
        var slot = player.Slot;
        var steamId = player.SteamID;
        if (!_restoreScheduled.Add(slot))
            return;
        AddTimer(delay, () => TryRestore(slot, steamId, 1), TimerFlags.STOP_ON_MAPCHANGE);
    }

    // Hides the admin again with SimpleAdmin's own command, retrying until their permissions load.
    private void TryRestore(int slot, ulong steamId, int attempt)
    {
        var player = Utilities.GetPlayerFromSlot(slot);
        if (player is not { IsValid: true, IsBot: false } || player.SteamID != steamId ||
            !_hidden.Contains(steamId) || _simpleAdmin == null)
        {
            _restoreScheduled.Remove(slot);
            _restoring.Remove(slot);
            return;
        }

        if (_simpleAdmin.IsAdminSilent(player))
        {
            _restoreScheduled.Remove(slot);
            _restoring.Remove(slot);
            MoveOffTeams(player);
            return;
        }

        // css_hide toggles, so running it again after it didn't seem to take could unhide them. That
        // happens when SimpleAdmin was hot-reloaded: CSS keeps handing out the old instance's API.
        if (_restoring.Contains(slot))
        {
            _restoreScheduled.Remove(slot);
            _restoring.Remove(slot);
            Logger.LogWarning("Ran css_hide for {Name} ({SteamId}) but SimpleAdmin doesn't report them hidden. " +
                              "If CS2-SimpleAdmin was reloaded without a server restart, restart the server.",
                player.PlayerName, steamId);
            return;
        }

        if (attempt > RestoreAttempts)
        {
            _restoreScheduled.Remove(slot);
            _restoring.Remove(slot);
            _hidden.Remove(steamId);
            SaveHidden();
            player.PrintToChat(" You couldn't be hidden again, so you're visible now.");
            Logger.LogWarning("Couldn't hide {Name} ({SteamId}) again; forgot they were hidden", player.PlayerName, steamId);
            return;
        }

        if (CanHide(player))
        {
            _restoring.Add(slot);
            player.ExecuteClientCommandFromServer(_hideAliases[0]);
        }
        AddTimer(RestoreDelay, () => TryRestore(slot, steamId, attempt + 1), TimerFlags.STOP_ON_MAPCHANGE);
    }

    // Whether the player may use css_hide: an admin_overrides.json override of it wins, checked the way
    // CSS checks the typed command ("all" needs every flag, anything else one of them).
    private bool CanHide(CCSPlayerController player)
    {
        var command = _hideAliases[0];
        var data = AdminManager.GetCommandOverrideData(command);
        if (data == null || !data.Enabled)
            return AdminManager.PlayerHasPermissions(player, HidePermission);

        var flags = data.Flags.ToArray();
        BaseRequiresPermissions check = data.CheckType == "all"
            ? new RequiresPermissions(flags)
            : new RequiresPermissionsOr(flags);
        check.Command = command;
        return check.CanExecuteCommand(player);
    }

    // For an admin SimpleAdmin still counts as hidden who ended up on a team anyway.
    private static void MoveOffTeams(CCSPlayerController player)
    {
        if (player.TeamNum <= (byte)CsTeam.Spectator)
            return;

        if (player.PlayerPawn.Value is { IsValid: true, LifeState: (byte)LifeState_t.LIFE_ALIVE } pawn)
            pawn.CommitSuicide(true, false);
        player.ChangeTeam(CsTeam.Spectator);
        Server.NextFrame(() =>
        {
            if (player.IsValid)
                player.ChangeTeam(CsTeam.None);
        });
    }

    [GameEventHandler(HookMode.Pre)]
    public HookResult OnPlayerConnect(EventPlayerConnect @event, GameEventInfo info)
    {
        if (!@event.Bot && _hidden.Contains(@event.Xuid))
            info.DontBroadcast = true;
        return HookResult.Continue;
    }

    // Also fires for everyone on a map change, which is when SimpleAdmin forgets who was hidden.
    [GameEventHandler(HookMode.Pre)]
    public HookResult OnPlayerConnectFull(EventPlayerConnectFull @event, GameEventInfo info)
    {
        var player = @event.Userid;
        if (player is not { IsValid: true, IsBot: false } || !_hidden.Contains(player.SteamID))
            return HookResult.Continue;

        info.DontBroadcast = true;
        ScheduleRestore(player, RestoreDelay);

        // Put them in spectators straight away so they skip the team select screen, rather than
        // waiting for the restore. SimpleAdmin doesn't count them as hidden yet, so this doesn't
        // unhide them; the restore then moves them from spectators to hidden.
        var slot = player.Slot;
        var steamId = player.SteamID;
        AddTimer(SkipTeamSelectDelay, () =>
        {
            var p = Utilities.GetPlayerFromSlot(slot);
            if (p is { IsValid: true } && p.SteamID == steamId && _hidden.Contains(steamId) &&
                p.TeamNum == (byte)CsTeam.None && _simpleAdmin?.IsAdminSilent(p) != true)
            {
                p.ChangeTeam(CsTeam.Spectator);
            }
        }, TimerFlags.STOP_ON_MAPCHANGE);
        return HookResult.Continue;
    }

    [GameEventHandler(HookMode.Pre)]
    public HookResult OnPlayerTeam(EventPlayerTeam @event, GameEventInfo info)
    {
        var player = @event.Userid;
        if (!IsHidden(player))
            return HookResult.Continue;

        info.DontBroadcast = true;
        // Still tell the admin themselves: their client closes the team screen on it.
        SendTeamEvent(player!, @event.Team, @event.Oldteam);
        if (@event.Team > (int)CsTeam.Spectator && _hidden.Contains(player!.SteamID))
            ScheduleRestore(player, 0.1f);
        return HookResult.Continue;
    }

    private static void SendTeamEvent(CCSPlayerController player, int team, int oldTeam)
    {
        var copy = new EventPlayerTeam(true)
        {
            Userid = player,
            Team = team,
            Oldteam = oldTeam,
            Disconnect = false,
            Silent = true,
            Isbot = false,
            Name = player.PlayerName,
        };
        copy.FireEventToClient(player);
        copy.Free();
    }

    [GameEventHandler(HookMode.Pre)]
    public HookResult OnPlayerDeath(EventPlayerDeath @event, GameEventInfo info)
    {
        if (IsHidden(@event.Userid))
            info.DontBroadcast = true;
        return HookResult.Continue;
    }

    // Pre runs before SimpleAdmin's own handler forgets the player was hidden.
    [GameEventHandler(HookMode.Pre)]
    public HookResult OnPlayerDisconnect(EventPlayerDisconnect @event, GameEventInfo info)
    {
        var player = @event.Userid;
        if (IsHidden(player))
            info.DontBroadcast = true;
        if (player is { IsValid: true })
        {
            _hideTyped.Remove(player.Slot);
            _restoreScheduled.Remove(player.Slot);
            _restoring.Remove(player.Slot);
        }
        return HookResult.Continue;
    }

    private bool IsHidden(CCSPlayerController? player)
    {
        return player is { IsValid: true, IsBot: false } &&
               (_hidden.Contains(player.SteamID) || _simpleAdmin?.IsAdminSilent(player) == true);
    }

    private string ChatAlias()
    {
        var alias = _hideAliases[0];
        return alias.StartsWith("css_") ? "!" + alias[4..] : alias;
    }

    // SimpleAdmin lets Commands.json rename css_hide, so listen for whatever it's called there.
    private string[] ReadHideAliases()
    {
        var path = Path.Combine(ConfigDirectory, "CS2-SimpleAdmin", "Commands.json");
        try
        {
            using var doc = JsonDocument.Parse(File.ReadAllText(path));
            var aliases = doc.RootElement.GetProperty("commands").GetProperty("css_hide").GetProperty("aliases")
                .EnumerateArray().Select(a => a.GetString()).OfType<string>().ToArray();
            if (aliases.Length > 0)
                return aliases;
        }
        catch (Exception ex) when (ex is IOException or JsonException or KeyNotFoundException or InvalidOperationException)
        {
            Logger.LogWarning("Couldn't read css_hide's aliases from {Path} ({Error}); using css_hide and css_stealth",
                path, ex.Message);
        }
        return ["css_hide", "css_stealth"];
    }

    private void LoadHidden()
    {
        _hidden.Clear();
        if (!File.Exists(HiddenPath))
            return;
        try
        {
            _hidden.UnionWith(JsonSerializer.Deserialize<List<ulong>>(File.ReadAllText(HiddenPath)) ?? []);
        }
        catch (Exception ex) when (ex is IOException or JsonException)
        {
            Logger.LogError("Couldn't read {Path}: {Error}", HiddenPath, ex.Message);
        }
    }

    private void SaveHidden()
    {
        try
        {
            Directory.CreateDirectory(Path.GetDirectoryName(HiddenPath)!);
            File.WriteAllText(HiddenPath, JsonSerializer.Serialize(_hidden.Order().ToList()));
        }
        catch (IOException ex)
        {
            Logger.LogError("Couldn't write {Path}: {Error}", HiddenPath, ex.Message);
        }
    }
}