using System.Collections.Generic;
using Xunit;
using XWorld.Framework;
using XWorld.Framework.Protocol;
using XWorld.Server.Host;
using XWorld.Server.Gateway;

namespace XWorld.Server.Gateway.Tests
{
    public class ServerLoopTests
    {
        private static ServerLoop NewLoop(long reconnectWindow = 100)
            => new ServerLoop(TestGames.Root, new ConsoleLogger("[loop]"), reconnectWindow);

        private static byte[] JoinFrame(string gameId, int version)
            => FrameCodec.Encode(new Frame(Channel.Framework, (ushort)FrameworkOpcode.MatchRequest,
                new MatchRequestMsg { GameId = gameId, Version = version }.Encode()));

        private static Frame LobbyJoinFrame(string name)
            => new Frame(Channel.Framework, (ushort)FrameworkOpcode.LobbyJoin,
                new LobbyJoinMsg { Name = name, Figure = 1 }.Encode());

        private static Frame LobbyMoveFrame(float x, float z, bool moving)
            => new Frame(Channel.Framework, (ushort)FrameworkOpcode.LobbyMove,
                new LobbyMoveMsg
                {
                    X = x,
                    Y = 0f,
                    Z = z,
                    DirX = 1f,
                    DirZ = 0f,
                    Moving = moving
                }.Encode());

        private static Frame WorldChatFrame(string text)
            => new Frame(Channel.Framework, (ushort)FrameworkOpcode.WorldChatSend,
                new WorldChatSendMsg { Text = text }.Encode());

        private static List<Frame> Frames(FakeConnection c)
        {
            var list = new List<Frame>();
            foreach (var bytes in c.Sent) list.Add(FrameCodec.Decode(bytes));
            return list;
        }

        [Fact]
        public void Heartbeat_IsEchoed()
        {
            var loop = NewLoop();
            var c = new FakeConnection(1);
            loop.Submit(new ConnectCommand { PlayerId = 1, Connection = c });
            var hb = new HeartbeatMsg { ClientTimeMs = 123456789L };
            loop.Submit(new FrameCommand { PlayerId = 1,
                Frame = new Frame(Channel.Framework, (ushort)FrameworkOpcode.Heartbeat, hb.Encode()) });

            loop.DrainAndTick(0f);

            var echo = Frames(c).Find(f => f.Channel == Channel.Framework && f.Opcode == (ushort)FrameworkOpcode.Heartbeat);
            Assert.NotEqual(default, echo);
            Assert.Equal(123456789L, HeartbeatMsg.Decode(echo.Payload).ClientTimeMs);
        }

        [Fact]
        public void LobbyMove_IsBroadcastToAllLobbyPlayers()
        {
            var loop = NewLoop();
            var c1 = new FakeConnection(1);
            var c2 = new FakeConnection(2);
            loop.Submit(new ConnectCommand { PlayerId = 1, Connection = c1 });
            loop.Submit(new ConnectCommand { PlayerId = 2, Connection = c2 });
            loop.Submit(new FrameCommand { PlayerId = 1, Frame = LobbyJoinFrame("editor") });
            loop.Submit(new FrameCommand { PlayerId = 2, Frame = LobbyJoinFrame("android") });
            loop.DrainAndTick(0f);

            c1.Sent.Clear();
            c2.Sent.Clear();
            loop.Submit(new FrameCommand { PlayerId = 1, Frame = LobbyMoveFrame(3f, 4f, true) });
            loop.DrainAndTick(0f);

            Frame moveToSelf = Frames(c1).Find(f => f.Channel == Channel.Framework && f.Opcode == (ushort)FrameworkOpcode.LobbyMove);
            Frame moveToOther = Frames(c2).Find(f => f.Channel == Channel.Framework && f.Opcode == (ushort)FrameworkOpcode.LobbyMove);
            Assert.NotEqual(default, moveToSelf);
            Assert.NotEqual(default, moveToOther);

            LobbyMoveMsg decoded = LobbyMoveMsg.Decode(moveToOther.Payload);
            Assert.Equal(1, decoded.PlayerId);
            Assert.Equal(3f, decoded.X);
            Assert.Equal(4f, decoded.Z);
            Assert.True(decoded.Moving);
        }

        [Fact]
        public void WorldChat_IsBroadcastToAllConnectedPlayers()
        {
            var loop = NewLoop();
            var c1 = new FakeConnection(1);
            var c2 = new FakeConnection(2);
            loop.Submit(new ConnectCommand { PlayerId = 1, Connection = c1 });
            loop.Submit(new ConnectCommand { PlayerId = 2, Connection = c2 });
            loop.Submit(new FrameCommand { PlayerId = 1, Frame = LobbyJoinFrame("Alice") });
            loop.Submit(new FrameCommand { PlayerId = 2, Frame = LobbyJoinFrame("Bob") });
            loop.DrainAndTick(0f);

            c1.Sent.Clear();
            c2.Sent.Clear();
            loop.Submit(new FrameCommand { PlayerId = 1, Frame = WorldChatFrame("hello world") });
            loop.DrainAndTick(0f);

            Frame selfFrame = Frames(c1).Find(f => f.Channel == Channel.Framework && f.Opcode == (ushort)FrameworkOpcode.WorldChatMessage);
            Frame otherFrame = Frames(c2).Find(f => f.Channel == Channel.Framework && f.Opcode == (ushort)FrameworkOpcode.WorldChatMessage);
            Assert.NotEqual(default, selfFrame);
            Assert.NotEqual(default, otherFrame);

            WorldChatMessageMsg message = WorldChatMessageMsg.Decode(otherFrame.Payload);
            Assert.Equal(1, message.PlayerId);
            Assert.Equal("Alice", message.PlayerName);
            Assert.Equal("hello world", message.Text);
            Assert.True(message.ServerTimeMs > 0);
        }

        [Fact]
        public void Reconnect_ReroutesRoomOutputToNewConnection()
        {
            var loop = NewLoop(reconnectWindow: 100);
            var c1 = new FakeConnection(1);
            var c2 = new FakeConnection(2);
            loop.Submit(new ConnectCommand { PlayerId = 1, Connection = c1 });
            loop.Submit(new ConnectCommand { PlayerId = 2, Connection = c2 });
            loop.Submit(new FrameCommand { PlayerId = 1, Frame = FrameCodec.Decode(JoinFrame("rps", 1)) });
            loop.Submit(new FrameCommand { PlayerId = 2, Frame = FrameCodec.Decode(JoinFrame("rps", 1)) });
            loop.DrainAndTick(1f); // 2 人成团：c1/c2 收到 MatchFound + 快照
            Assert.True(c1.Sent.Count >= 2);

            // pid=1 断线后重连到新连接 c1b
            loop.Submit(new DisconnectCommand { PlayerId = 1, Connection = c1 });
            var c1b = new FakeConnection(1);
            loop.Submit(new ConnectCommand { PlayerId = 1, Connection = c1b });
            loop.DrainAndTick(1f); // 房间仍在跑（60s 未到）：下一快照应发往 c1b

            Assert.Contains(Frames(c1b), f => f.Channel == Channel.Game);
        }

        [Fact]
        public void Reconnect_ReplaysMatchFoundAndLatestGameSnapshot()
        {
            var loop = NewLoop(reconnectWindow: 100);
            var c1 = new FakeConnection(1);
            var c2 = new FakeConnection(2);
            loop.Submit(new ConnectCommand { PlayerId = 1, Connection = c1 });
            loop.Submit(new ConnectCommand { PlayerId = 2, Connection = c2 });
            loop.Submit(new FrameCommand { PlayerId = 1, Frame = FrameCodec.Decode(JoinFrame("rps", 1)) });
            loop.Submit(new FrameCommand { PlayerId = 2, Frame = FrameCodec.Decode(JoinFrame("rps", 1)) });
            loop.DrainAndTick(1f);

            loop.Submit(new DisconnectCommand { PlayerId = 1, Connection = c1 });
            loop.DrainAndTick(1f);

            var c1b = new FakeConnection(1);
            loop.Submit(new ConnectCommand { PlayerId = 1, Connection = c1b });
            loop.DrainAndTick(0f);

            Frame resumeFrame = Frames(c1b).Find(f =>
                f.Channel == Channel.Framework && f.Opcode == (ushort)FrameworkOpcode.MatchFound);
            Assert.NotEqual(default, resumeFrame);
            MatchFoundMsg resume = MatchFoundMsg.Decode(resumeFrame.Payload);
            Assert.Equal("rps", resume.GameId);
            Assert.Equal(1, resume.Version);
            Assert.Equal(1, resume.SelfPlayerId);
            Assert.Equal(2, resume.Players.Count);
            Assert.Contains(Frames(c1b), f => f.Channel == Channel.Game);
        }

        [Fact]
        public void DefaultReconnectWindow_IsThreeMinutesAtDefaultTickRate()
        {
            Assert.Equal(1800, ServerLoop.DefaultReconnectWindowTicks);
        }

        [Fact]
        public void ExpiredSession_IsSwept()
        {
            var loop = NewLoop(reconnectWindow: 2);
            var c = new FakeConnection(1);
            loop.Submit(new ConnectCommand { PlayerId = 1, Connection = c });
            loop.DrainAndTick(1f); // _tick: 0→1
            loop.Submit(new DisconnectCommand { PlayerId = 1, Connection = c });
            loop.DrainAndTick(1f); // 排空时 _tick=1 → DisconnectedAtTick=1；随后 _tick→2
            loop.DrainAndTick(1f); // _tick→3：3-1=2，不 >2，保留
            loop.DrainAndTick(1f); // _tick→4：4-1=3 >2 → 过期清除
            Assert.False(loop.HasSession(1));
        }

        [Fact]
        public void DuplicateMatchRequest_WhileInRoom_IsRejectedWithError()
        {
            var loop = NewLoop();
            var c1 = new FakeConnection(1);
            var c2 = new FakeConnection(2);
            loop.Submit(new ConnectCommand { PlayerId = 1, Connection = c1 });
            loop.Submit(new ConnectCommand { PlayerId = 2, Connection = c2 });
            loop.Submit(new FrameCommand { PlayerId = 1, Frame = FrameCodec.Decode(JoinFrame("rps", 1)) });
            loop.Submit(new FrameCommand { PlayerId = 2, Frame = FrameCodec.Decode(JoinFrame("rps", 1)) });
            loop.DrainAndTick(1f); // 2 人入房

            // 已在房间内再次 join → 回 Error
            loop.Submit(new FrameCommand { PlayerId = 1, Frame = FrameCodec.Decode(JoinFrame("rps", 1)) });
            loop.DrainAndTick(1f);

            Assert.Contains(Frames(c1), f => f.Channel == Channel.Framework && f.Opcode == (ushort)FrameworkOpcode.Error);
        }

        [Fact]
        public void MatchCancel_WhileQueued_CancelsQueuedMatchAndAllowsPlayerToMatchAgain()
        {
            var loop = NewLoop();
            var c = new FakeConnection(1);
            loop.Submit(new ConnectCommand { PlayerId = 1, Connection = c });
            loop.Submit(new FrameCommand { PlayerId = 1, Frame = FrameCodec.Decode(JoinFrame("rps", 1)) });
            loop.DrainAndTick(1f);

            c.Sent.Clear();
            loop.Submit(new FrameCommand { PlayerId = 1, Frame = new Frame(Channel.Framework, (ushort)FrameworkOpcode.MatchCancel, System.Array.Empty<byte>()) });
            loop.Submit(new FrameCommand { PlayerId = 1, Frame = new Frame(Channel.Framework, (ushort)FrameworkOpcode.RandomMatchRequest, System.Array.Empty<byte>()) });
            loop.DrainAndTick(1f);

            Assert.Contains(Frames(c), f => f.Channel == Channel.Framework && f.Opcode == (ushort)FrameworkOpcode.MatchAssigned);
            Assert.DoesNotContain(Frames(c), f =>
                f.Channel == Channel.Framework &&
                f.Opcode == (ushort)FrameworkOpcode.Error &&
                ErrorMsg.Decode(f.Payload).Message == "already in room or queue");
        }

        [Fact]
        public void GameFrame_WithNoRoom_IsIgnoredSafely()
        {
            var loop = NewLoop();
            var c = new FakeConnection(1);
            loop.Submit(new ConnectCommand { PlayerId = 1, Connection = c });
            var w = new PacketWriter(); w.WriteVarInt(3);
            loop.Submit(new FrameCommand { PlayerId = 1, Frame = new Frame(Channel.Game, 0, w.ToArray()) });

            var ex = Record.Exception(() => loop.DrainAndTick(1f));
            Assert.Null(ex);       // 无房间的游戏帧被安全忽略，不抛
            Assert.Empty(c.Sent);  // 无任何输出
        }

        [Fact]
        public void MatchRequest_WithNoSession_IsIgnoredSafely()
        {
            var loop = NewLoop();
            // 未发 ConnectCommand，直接来一个 join 帧
            loop.Submit(new FrameCommand { PlayerId = 99, Frame = FrameCodec.Decode(JoinFrame("rps", 1)) });
            var ex = Record.Exception(() => loop.DrainAndTick(1f));
            Assert.Null(ex);
            Assert.False(loop.HasSession(99));
        }
    }
}