using System;
using System.Collections.Generic;
using UnityEngine;
using XWorld.Framework;
using XWorld.Framework.Protocol;

namespace XGame.MiniGame
{
    // 客户端到服务端的帧通道。每帧轮询底层 socket，解码出的帧分发：
    //   Game 帧 -> OnGameMessage(NetMessage)（交给 IGameClient.OnNetMessage）
    //   Framework 帧 -> OnFrameworkFrame(Frame)（宿主处理 MatchFound/RoomEnd 等）
    public sealed class MiniGameNetChannel
    {
        private readonly XWebSocket _sock;
        private readonly List<byte> _recvBuffer = new List<byte>(4096);
        public Action<NetMessage> OnGameMessage;
        public Action<Frame> OnFrameworkFrame;

        public MiniGameNetChannel(XWebSocket sock) { _sock = sock; }

        public bool IsConnected => _sock != null && _sock.IsConected();

        // 业务输入：IGameClient 调 ctx.Send(NetMessage) -> 这里包成 Game 帧发出
        public void SendGame(NetMessage msg)
        {
            byte[] frame = FrameCodec.Encode(new Frame(Channel.Game, msg.Opcode, msg.Payload));
            SendRaw(frame);
        }

        public void SendFramework(FrameworkOpcode op, byte[] payload)
        {
            byte[] frame = FrameCodec.Encode(new Frame(Channel.Framework, (ushort)op, payload));
            SendRaw(frame);
        }

        private void SendRaw(byte[] frame)
        {
            string err = null;
            _sock.send(frame, null, ref err);
            if (!string.IsNullOrEmpty(err)) Debug.LogError("[MiniGameNetChannel] send err: " + err);
        }

        // 每帧由宿主调用：把底层收到的字节解出并分发。
        // XWebSocket 会把多条 WS 消息追加到同一个 buffer；Frame 自带 payloadLen，
        // 所以这里按 FrameCodec 的线网格式从累计字节流中拆出 0..N 帧。
        public void Pump()
        {
            if (_sock == null) return;
            string err = null;
            while (_sock.isDataRecv())
            {
                byte[] data = _sock.recv(ref err);
                if (!string.IsNullOrEmpty(err)) { Debug.LogError("[MiniGameNetChannel] recv err: " + err); break; }
                if (data == null || data.Length == 0) break;
                _recvBuffer.AddRange(data);
            }

            while (TryPopFrame(out var frameBytes))
            {
                Frame f;
                try { f = FrameCodec.Decode(frameBytes); }
                catch (FormatException) { Debug.LogWarning("[MiniGameNetChannel] 畸形帧，丢弃"); continue; }

                if (f.Channel == Channel.Game) OnGameMessage?.Invoke(new NetMessage(f.Opcode, f.Payload));
                else OnFrameworkFrame?.Invoke(f);
            }
        }

        private bool TryPopFrame(out byte[] frameBytes)
        {
            frameBytes = null;
            if (_recvBuffer.Count < 4) return false; // channel + opcode + at least 1-byte payload len

            int pos = 3;
            uint payloadLen = 0;
            int shift = 0;
            while (true)
            {
                if (pos >= _recvBuffer.Count) return false;
                if (shift > 28)
                {
                    Debug.LogWarning("[MiniGameNetChannel] payloadLen varuint too long, clear buffer");
                    _recvBuffer.Clear();
                    return false;
                }

                byte b = _recvBuffer[pos++];
                if (shift == 28 && (b & 0x70) != 0)
                {
                    Debug.LogWarning("[MiniGameNetChannel] payloadLen overflow, clear buffer");
                    _recvBuffer.Clear();
                    return false;
                }

                payloadLen |= (uint)(b & 0x7F) << shift;
                if ((b & 0x80) == 0) break;
                shift += 7;
            }

            if (payloadLen > 1024 * 1024)
            {
                Debug.LogWarning("[MiniGameNetChannel] frame too large, clear buffer");
                _recvBuffer.Clear();
                return false;
            }

            int totalLen = pos + (int)payloadLen;
            if (_recvBuffer.Count < totalLen) return false;

            frameBytes = _recvBuffer.GetRange(0, totalLen).ToArray();
            _recvBuffer.RemoveRange(0, totalLen);
            return true;
        }
    }
}