using LiteNetLib;
using LiteNetLib.Utils;
using MMOserver.Api;
using MMOserver.Game.Channel;
using MMOserver.Packet;
using MMOserver.Utils;
using ProtoBuf;
using Serilog;
using ServerLib.Packet;
using ServerLib.Service;

namespace MMOserver.Game;

public class GameServer : ServerBase
{
    private readonly Dictionary<ushort, Action<NetPeer, long, byte[]>> packetHandlers;

    public GameServer(int port, string connectionString) : base(port, connectionString)
    {
        packetHandlers = new Dictionary<ushort, Action<NetPeer, long, byte[]>>
        {
            [(ushort)PacketCode.INTO_CHANNEL] = OnIntoChannel,
            [(ushort)PacketCode.EXIT_CHANNEL] = OnExitChannel,
            [(ushort)PacketCode.TRANSFORM_PLAYER] = OnTransformPlayer,
            [(ushort)PacketCode.ACTION_PLAYER] = OnActionPlayer,
            [(ushort)PacketCode.STATE_PLAYER] = OnStatePlayer,
        };
    }

    protected override void HandleEcho(NetPeer peer, byte[] payload)
    {
        if (payload.Length < 4)
        {
            Log.Warning("[Server] Echo 페이로드 크기 오류 PeerId={Id} Length={Len}", peer.Id, payload.Length);
            return;
        }

        // 세션에 넣지는 않는다.
        NetDataReader reader = new NetDataReader(payload);
        short code = reader.GetShort();
        short bodyLength = reader.GetShort();

        EchoPacket echoPacket = Serializer.Deserialize<EchoPacket>(payload.AsMemory(4));
        Log.Debug("[Echo] : addr={Addr}, str={Str}", peer.Address, echoPacket.Str);
        // Echo메시지는 순서보장 안함 HOL Blocking 제거
        SendTo(peer, payload, DeliveryMethod.ReliableUnordered);
    }

    protected override void HandleAuthDummy(NetPeer peer, byte[] payload)
    {
        DummyAccTokenPacket accTokenPacket = Serializer.Deserialize<DummyAccTokenPacket>(new ReadOnlyMemory<byte>(payload));
        long hashKey = accTokenPacket.Token;

        if (sessions.TryGetValue(hashKey, out NetPeer? existing))
        {
            // WiFi → LTE 전환 등 재연결: 이전 피어 교체
            existing.Tag = null;
            sessions.Remove(hashKey);
            Log.Information("[Server] 재연결 HashKey={Key} Old={Old} New={New}", hashKey, existing.Id, peer.Id);
            existing.Disconnect();
        }

        peer.Tag = new Session(hashKey, peer);
        sessions[hashKey] = peer;
        pendingPeers.Remove(peer.Id);

        if (hashKey <= 1000)
        {
            // 더미 클라다.
            ChannelManager cm = ChannelManager.Instance;
            cm.AddUser(1, hashKey, new Player());
        }
        else
        {
            Log.Error("[Server] Dummy 클라이언트가 아닙니다. 연결을 종료합니다. HashKey={Key} PeerId={Id}", hashKey, peer.Id);
            peer.Disconnect();
            return;
        }

        Log.Information("[Server] 인증 완료 HashKey={Key} PeerId={Id}", hashKey, peer.Id);
        OnSessionConnected(peer, hashKey);
    }

    protected override async void HandleAuth(NetPeer peer, byte[] payload)
    {
        AccTokenPacket accTokenPacket = Serializer.Deserialize<AccTokenPacket>(new ReadOnlyMemory<byte>(payload));
        string token = accTokenPacket.Token;
        tokenHash.TryGetValue(token, out long hashKey);
        if (hashKey <= 1000)
        {
            hashKey = UuidGeneratorManager.Instance.Create();
        }

        if (sessions.TryGetValue(hashKey, out NetPeer? existing))
        {
            // WiFi → LTE 전환 등 재연결: 이전 피어 교체 (토큰 재검증 불필요)
            existing.Tag = null;
            sessions.Remove(hashKey);
            Log.Information("[Server] 재연결 HashKey={Key} Old={Old} New={New}", hashKey, existing.Id, peer.Id);
            existing.Disconnect();
        }
        else
        {
            // 신규 연결: 웹서버에 JWT 검증 요청
            string? username = await RestApi.Instance.VerifyTokenAsync(token);
            if (username == null)
            {
                Log.Warning("[Server] 토큰 검증 실패 - 연결 거부 PeerId={Id}", peer.Id);
                UuidGeneratorManager.Instance.Release(hashKey);
                peer.Disconnect();
                return;
            }

            Log.Information("[Server] 토큰 검증 성공 Username={Username} PeerId={Id}", username, peer.Id);
        }

        peer.Tag = new Session(hashKey, peer);
        ((Session)peer.Tag).Token = token;
        sessions[hashKey] = peer;
        tokenHash[token] = hashKey;
        pendingPeers.Remove(peer.Id);

        Log.Information("[Server] 인증 완료 HashKey={Key} PeerId={Id}", hashKey, peer.Id);
        OnSessionConnected(peer, hashKey);
    }

    protected override void OnSessionConnected(NetPeer peer, long hashKey)
    {
        Log.Information("[GameServer] 세션 연결 HashKey={Key} PeerId={Id}", hashKey, peer.Id);

        // 만약 wifi-lte 로 바꿔졌다 이때 이미 로비에 들어가 있다면 넘긴다.
        ChannelManager cm = ChannelManager.Instance;
        int channelId = cm.HasUser(hashKey);

        if (channelId >= 0)
        {
            // 재연결: 채널 유저 목록 전송 (채널 선택 스킵, 바로 마을로)
            SendIntoChannelPacket(peer, hashKey);
        }
        else
        {
            // 모든 채널 정보 던진다
            SendLoadChannelPacket(peer, hashKey);
        }
    }

    protected override void OnSessionDisconnected(NetPeer peer, long hashKey, DisconnectInfo info)
    {
        ChannelManager cm = ChannelManager.Instance;
        if (cm.RemoveUser(hashKey))
        {
            Log.Information("[GameServer] 세션 해제 HashKey={Key} Reason={Reason}", hashKey, info.Reason);
        }
        UuidGeneratorManager.Instance.Release(hashKey);
    }

    protected override void HandlePacket(NetPeer peer, long hashKey, ushort type, byte[] payload)
    {
        if (packetHandlers.TryGetValue(type, out Action<NetPeer, long, byte[]>? handler))
        {
            handler(peer, hashKey, payload);
        }
        else
        {
            Log.Warning("[GameServer] 알 수 없는 패킷 Type={Type}", type);
        }
    }

    // ============================================================
    // 보내는 패킷
    // ============================================================

    private void SendLoadChannelPacket(NetPeer peer, long hashKey)
    {
        LoadChannelPacket loadChannelPacket = new LoadChannelPacket();
        foreach (Channel.Channel channel in ChannelManager.Instance.GetChannels())
        {
            ChannelInfo info = new ChannelInfo();
            info.ChannelId = channel.ChannelId;
            info.ChannelUserConut = channel.UserCount;
            info.ChannelUserMax = channel.UserCountMax;
            loadChannelPacket.Channels.Add(info);
        }

        byte[] data = PacketSerializer.Serialize<LoadChannelPacket>((ushort)PacketCode.LOAD_CHANNEL, loadChannelPacket);
        SendTo(peer, data);
    }

    // 나간 유저를 같은 채널 유저들에게 알림 (UPDATE_CHANNEL_USER IsAdd=false)
    private void SendExitChannelPacket(NetPeer peer, long hashKey, int channelId, Player player)
    {
        UpdateChannelUserPacket packet = new UpdateChannelUserPacket
        {
            Players = ToPlayerInfo(player),
            IsAdd = false
        };
        byte[] data = PacketSerializer.Serialize<UpdateChannelUserPacket>((ushort)PacketCode.UPDATE_CHANNEL_USER, packet);
        // 이미 채널에서 제거된 후라 나간 본인에게는 전송되지 않음
        BroadcastToChannel(channelId, data);
    }

    // 채널 입장 시 패킷 전송
    //  - 새 유저에게 : 기존 채널 유저 목록 (INTO_CHANNEL)
    //  - 기존 유저들에게 : 새 유저 입장 알림 (UPDATE_CHANNEL_USER IsAdd=true)
    private void SendIntoChannelPacket(NetPeer peer, long hashKey)
    {
        ChannelManager cm = ChannelManager.Instance;
        int channelId = cm.HasUser(hashKey);
        if (channelId < 0)
        {
            return;
        }

        Channel.Channel channel = cm.GetChannel(channelId);
        Player? myPlayer = channel.GetPlayer(hashKey);

        // 1. 새 유저에게: 자신을 제외한 기존 채널 유저 목록 전송
        IntoChannelPacket response = new IntoChannelPacket { ChannelId = channelId };
        foreach (long userId in channel.GetConnectUsers())
        {
            if (userId == hashKey)
            {
                continue;
            }

            Player? p = channel.GetPlayer(userId);
            if (p != null)
            {
                response.Players.Add(ToPlayerInfo(p));
            }
        }

        byte[] toNewUser = PacketSerializer.Serialize<IntoChannelPacket>((ushort)PacketCode.INTO_CHANNEL, response);
        SendTo(peer, toNewUser);

        // 2. 기존 유저들에게: 새 유저 입장 알림
        if (myPlayer != null)
        {
            UpdateChannelUserPacket notify = new UpdateChannelUserPacket
            {
                Players = ToPlayerInfo(myPlayer),
                IsAdd = true
            };
            byte[] toOthers = PacketSerializer.Serialize<UpdateChannelUserPacket>((ushort)PacketCode.UPDATE_CHANNEL_USER, notify);
            BroadcastToChannel(channelId, toOthers, peer);
        }
    }

    // ============================================================
    // 채널 브로드캐스트 헬퍼
    // ============================================================

    // 특정 채널의 모든 유저에게 전송 (exclude 지정 시 해당 피어 제외)
    private void BroadcastToChannel(int channelId, byte[] data, NetPeer? exclude = null)
    {
        Channel.Channel channel = ChannelManager.Instance.GetChannel(channelId);
        foreach (long userId in channel.GetConnectUsers())
        {
            if (!sessions.TryGetValue(userId, out NetPeer? targetPeer))
            {
                continue;
            }

            if (exclude != null && targetPeer.Id == exclude.Id)
            {
                continue;
            }

            SendTo(targetPeer, data);
        }
    }

    // ============================================================
    // Player ↔ PlayerInfo 변환 (패킷 전송 시에만 사용)
    // ============================================================

    private static PlayerInfo ToPlayerInfo(Player player)
    {
        return new PlayerInfo
        {
            PlayerId = player.PlayerId,
            Nickname = player.Nickname,
            Level = player.Level,
            Hp = player.Hp,
            MaxHp = player.MaxHp,
            Mp = player.Mp,
            MaxMp = player.MaxMp,
            Position = new Vector3 { X = player.PosX, Y = player.PosY, Z = player.PosZ },
            RotY = player.RotY,
        };
    }

    // ============================================================
    // 패킷 핸들러
    // ============================================================

    private void OnIntoChannel(NetPeer peer, long hashKey, byte[] payload)
    {
        IntoChannelPacket packet = Serializer.Deserialize<IntoChannelPacket>(new ReadOnlyMemory<byte>(payload));

        ChannelManager cm = ChannelManager.Instance;

        // TODO: 실제 서비스에서는 DB/세션에서 플레이어 정보 로드 필요
        Player newPlayer = new Player
        {
            HashKey = hashKey,
            PlayerId = (int)(hashKey & 0x7FFFFFFF),
        };

        cm.AddUser(packet.ChannelId, hashKey, newPlayer);
        Log.Debug("[GameServer] INTO_CHANNEL HashKey={Key} ChannelId={ChannelId}", hashKey, packet.ChannelId);

        // 접속된 모든 유저 정보 전달
        SendIntoChannelPacket(peer, hashKey);
    }

    private void OnExitChannel(NetPeer peer, long hashKey, byte[] payload)
    {
        ExitChannelPacket packet = Serializer.Deserialize<ExitChannelPacket>(new ReadOnlyMemory<byte>(payload));

        ChannelManager cm = ChannelManager.Instance;

        // 제거 전에 채널/플레이어 정보 저장 (브로드캐스트에 필요)
        int channelId = cm.HasUser(hashKey);
        Player? player = channelId >= 0 ? cm.GetChannel(channelId).GetPlayer(hashKey) : null;

        cm.RemoveUser(hashKey);
        Log.Debug("[GameServer] EXIT_CHANNEL HashKey={Key} PlayerId={PlayerId}", hashKey, packet.PlayerId);

        // 같은 채널 유저들에게 나갔다고 알림
        if (channelId >= 0 && player != null)
        {
            SendExitChannelPacket(peer, hashKey, channelId, player);
        }
    }

    private void OnTransformPlayer(NetPeer peer, long hashKey, byte[] payload)
    {
        TransformPlayerPacket packet = Serializer.Deserialize<TransformPlayerPacket>(new ReadOnlyMemory<byte>(payload));

        ChannelManager cm = ChannelManager.Instance;
        int channelId = cm.HasUser(hashKey);
        if (channelId < 0)
        {
            return;
        }

        // 채널 내 플레이어 위치/방향 상태 갱신
        Player? player = cm.GetChannel(channelId).GetPlayer(hashKey);
        if (player != null)
        {
            player.PosX = packet.Position.X;
            player.PosY = packet.Position.Y;
            player.PosZ = packet.Position.Z;
            player.RotY = packet.RotY;
        }

        // 같은 채널 유저들에게 위치/방향 브로드캐스트 (나 제외)
        byte[] data = PacketSerializer.Serialize<TransformPlayerPacket>((ushort)PacketCode.TRANSFORM_PLAYER, packet);
        BroadcastToChannel(channelId, data, peer);
    }

    private void OnActionPlayer(NetPeer peer, long hashKey, byte[] payload)
    {
        ActionPlayerPacket packet = Serializer.Deserialize<ActionPlayerPacket>(new ReadOnlyMemory<byte>(payload));

        ChannelManager cm = ChannelManager.Instance;
        int channelId = cm.HasUser(hashKey);
        if (channelId < 0)
        {
            return;
        }

        // 같은 채널 유저들에게 행동 브로드캐스트 (나 제외)
        byte[] data = PacketSerializer.Serialize<ActionPlayerPacket>((ushort)PacketCode.ACTION_PLAYER, packet);
        BroadcastToChannel(channelId, data, peer);
    }

    private void OnStatePlayer(NetPeer peer, long hashKey, byte[] payload)
    {
        StatePlayerPacket packet = Serializer.Deserialize<StatePlayerPacket>(new ReadOnlyMemory<byte>(payload));

        ChannelManager cm = ChannelManager.Instance;
        int channelId = cm.HasUser(hashKey);
        if (channelId < 0)
        {
            return;
        }

        // 채널 내 플레이어 HP/MP 상태 갱신
        Player? player = cm.GetChannel(channelId).GetPlayer(hashKey);
        if (player != null)
        {
            player.Hp = packet.Hp;
            player.MaxHp = packet.MaxHp;
            player.Mp = packet.Mp;
            player.MaxMp = packet.MaxMp;
        }

        // 같은 채널 유저들에게 스테이트 브로드캐스트 (나 제외)
        byte[] data = PacketSerializer.Serialize<StatePlayerPacket>((ushort)PacketCode.STATE_PLAYER, packet);
        BroadcastToChannel(channelId, data, peer);
    }
}