using System.Collections.Concurrent;
using System.Net.WebSockets;
using System.Text.Json.Nodes;

namespace JJServiceManagerRelay;

/// <summary>접속 중인 대상 PC</summary>
public sealed class AgentConn
{
    public Guid DeviceId { get; init; }
    public string Name { get; set; }
    public string Hostname { get; set; }
    public WsJson Ws { get; init; }
    public string PublicIp { get; init; }
    public JsonArray LanIps { get; set; } = new();
    public JsonObject ActiveListen { get; set; }
    public string AppVersion { get; set; } = "";
    public DateTime ConnectedAt { get; } = DateTime.UtcNow;
    public CancellationTokenSource Cts { get; } = new();
    public JsonObject PendingReply { get; set; }
    public bool NotifyDevicesChanged { get; set; }
}

/// <summary>로그인한 관리 PC</summary>
public sealed class ManagerConn
{
    public Guid Id { get; } = Guid.NewGuid();
    public UserRow User { get; set; }
    public byte[] TokenHash { get; set; }
    public WsJson Ws { get; init; }
    public string Ip { get; init; }
    public string Host { get; set; } = "";
    public Dictionary<Guid, Perm> Perms { get; set; } = new();
    public DateTime LastExtend { get; set; } = DateTime.UtcNow;
    public CancellationTokenSource Cts { get; } = new();
    public JsonObject PendingReply { get; set; }

    public Perm PermFor(Guid deviceId) =>
        User.IsAdmin ? Perm.All : Perms.TryGetValue(deviceId, out var p) ? p : Perm.None;
}

/// <summary>관리 PC ↔ 대상 PC 연결 하나 (중개 → 직접 또는 중계)</summary>
public sealed class RelaySession
{
    public Guid Id { get; } = Guid.NewGuid();
    public Guid DeviceId { get; init; }
    public string DeviceName { get; init; }
    public long UserId { get; init; }
    public string Username { get; init; }
    public Guid ManagerConnId { get; init; }
    public string ManagerToken { get; } = Secrets.NewToken();
    public string AgentToken { get; } = Secrets.NewToken();
    public DateTime CreatedAt { get; } = DateTime.UtcNow;

    public readonly object Lock = new();
    public WebSocket ManagerWs;
    public WebSocket AgentWs;
    public bool ManagerUsed, AgentUsed;
    public bool Paired;
    public bool Direct;          // 관리 PC가 직접 연결에 성공했다고 알림
    public bool Finished;
    public long BytesToDevice, BytesFromDevice;
    public readonly TaskCompletionSource Done = new(TaskCreationOptions.RunContinuationsAsynchronously);
    /// <summary>직접 연결 성공 → 중계 통로에서 기다리던 쪽을 깨움</summary>
    public readonly TaskCompletionSource Wake = new(TaskCreationOptions.RunContinuationsAsynchronously);
}

/// <summary>서버 전체 상태</summary>
public sealed class Hub
{
    public Db Db { get; }
    public ServerConfig Config { get; }
    public ServerLog Log { get; }
    public TicketSigner Signer { get; set; }
    public Throttle Throttle { get; } = new();
    public DateTime StartedAt { get; } = DateTime.UtcNow;
    public string Version { get; } = typeof(Hub).Assembly.GetName().Version?.ToString(3) ?? "1.0.0";

    public ConcurrentDictionary<Guid, AgentConn> Agents { get; } = new();
    public ConcurrentDictionary<Guid, ManagerConn> Managers { get; } = new();
    public ConcurrentDictionary<Guid, RelaySession> Sessions { get; } = new();

    public Hub(Db db, ServerConfig config, ServerLog log)
    {
        Db = db;
        Config = config;
        Log = log;
    }

    public bool IsOnline(Guid deviceId) => Agents.ContainsKey(deviceId);

    // ───────────────────────── 알림 ─────────────────────────

    /// <summary>기기 온라인/오프라인을 볼 수 있는 관리 PC에 알림</summary>
    public async Task NotifyPresenceAsync(Guid deviceId, string name, string hostname, bool online)
    {
        var msg = new JsonObject
        {
            ["event"] = "presence",
            ["deviceId"] = deviceId.ToString(),
            ["name"] = name,
            ["hostname"] = hostname,
            ["online"] = online,
            ["at"] = Db.Iso(DateTime.UtcNow)
        };
        foreach (var m in Managers.Values)
        {
            if (m.User.MustChangePassword) continue;
            if (!m.PermFor(deviceId).Any) continue;
            await m.Ws.TrySendAsync((JsonObject)msg.DeepClone());
        }
    }

    /// <summary>기기 목록·권한이 바뀜 → 관리 PC들이 목록을 다시 받게</summary>
    public async Task NotifyDevicesChangedAsync()
    {
        foreach (var m in Managers.Values)
        {
            try
            {
                if (!m.User.IsAdmin) m.Perms = await Db.GetPermsForUserAsync(m.User.Id);
            }
            catch { }
            await m.Ws.TrySendAsync(new JsonObject { ["event"] = "devicesChanged" });
        }
    }

    /// <summary>사용자 계정이 바뀜 (사용 안 함·역할 변경) → 그 사용자의 연결을 다시 확인</summary>
    public async Task RefreshUserAsync(long userId, string kickReason = null)
    {
        var user = await Db.GetUserAsync(userId);
        foreach (var m in Managers.Values.Where(x => x.User.Id == userId).ToList())
        {
            if (user == null || !user.Enabled || kickReason != null)
            {
                await m.Ws.TrySendAsync(new JsonObject { ["event"] = "loggedOut", ["reason"] = kickReason ?? "계정을 사용할 수 없습니다." });
                m.Cts.Cancel();
                continue;
            }
            m.User = user;
            m.Perms = user.IsAdmin ? new() : await Db.GetPermsForUserAsync(user.Id);
            await m.Ws.TrySendAsync(new JsonObject { ["event"] = "devicesChanged" });
        }
    }

    /// <summary>기기를 사용 안 함/삭제 → 접속 중이면 끊음</summary>
    public async Task KickAgentAsync(Guid deviceId, string reason)
    {
        if (Agents.TryGetValue(deviceId, out var a))
        {
            await a.Ws.TrySendAsync(new JsonObject { ["event"] = "disabled", ["reason"] = reason });
            a.Cts.Cancel();
        }
    }

    // ───────────────────────── 연결 세션 정리 ─────────────────────────

    public async Task FinishSessionAsync(RelaySession s, string mode, string reason)
    {
        lock (s.Lock)
        {
            if (s.Finished) return;
            s.Finished = true;
        }
        Sessions.TryRemove(s.Id, out _);
        s.Done.TrySetResult();
        s.Wake.TrySetResult();
        await Db.ConnectionEndAsync(s.Id, mode, s.BytesToDevice, s.BytesFromDevice, reason);
    }

    /// <summary>30초마다: 아무도 붙지 않은 세션 정리, 만료 토큰 정리</summary>
    public async Task HousekeepingLoopAsync(CancellationToken ct)
    {
        var lastPurge = DateTime.MinValue;
        while (!ct.IsCancellationRequested)
        {
            try
            {
                await Task.Delay(TimeSpan.FromSeconds(10), ct);
                var now = DateTime.UtcNow;
                foreach (var s in Sessions.Values)
                {
                    bool stale;
                    lock (s.Lock) stale = !s.Paired && !s.Direct && now - s.CreatedAt > TimeSpan.FromSeconds(60);
                    if (stale) await FinishSessionAsync(s, "failed", "시간 초과 (양쪽이 연결되지 않음)");
                }
                if (now - lastPurge > TimeSpan.FromHours(1))
                {
                    lastPurge = now;
                    await Db.PurgeExpiredSessionsAsync();
                }
            }
            catch (OperationCanceledException) { break; }
            catch (Exception ex) { Log.Error("정리 작업 오류: " + ex.Message); }
        }
    }
}