// Copyright 2012-2026 The NATS Authors
// Licensed under the Apache License, Version 2.0

using System.Reflection;
using System.Text;
using System.Linq;
using Shouldly;
using ZB.MOM.NatsNet.Server;
using ZB.MOM.NatsNet.Server.Internal;

namespace ZB.MOM.NatsNet.Server.Tests;

public sealed class ClientConnectionStubFeaturesTests
{
    [Fact]
    public void ProcessConnect_ProcessPong_AndTimers_ShouldBehave()
    {
        var (server, err) = NatsServer.NewServer(new ServerOptions
        {
            PingInterval = TimeSpan.FromMilliseconds(20),
            AuthTimeout = 0.1,
        });
        err.ShouldBeNull();

        using var ms = new MemoryStream();
        var c = new ClientConnection(ClientKind.Client, server, ms)
        {
            Cid = 9,
            Trace = true,
        };

        var connectJson = Encoding.UTF8.GetBytes("{\"echo\":false,\"headers\":true,\"name\":\"unit\"}");
        c.ProcessConnect(connectJson);
        c.Opts.Name.ShouldBe("unit");
        c.Echo.ShouldBeFalse();
        c.Headers.ShouldBeTrue();

        c.RttStart = DateTime.UtcNow - TimeSpan.FromMilliseconds(50);
        c.ProcessPong();
        c.GetRttValue().ShouldBeGreaterThan(TimeSpan.Zero);

        c.SetPingTimer();
        GetTimer(c, "_pingTimer").ShouldNotBeNull();

        c.SetAuthTimer(TimeSpan.FromMilliseconds(20));
        GetTimer(c, "_atmr").ShouldNotBeNull();

        c.TraceMsg(Encoding.UTF8.GetBytes("MSG"));
        c.FlushSignal();
        c.UpdateS2AutoCompressionLevel();

        c.SetExpirationTimer(TimeSpan.Zero);
        c.IsClosed().ShouldBeTrue();
    }

    private static Timer? GetTimer(ClientConnection c, string field)
    {
        return (Timer?)typeof(ClientConnection)
            .GetField(field, BindingFlags.Instance | BindingFlags.NonPublic)!
            .GetValue(c);
    }

    [Fact]
    public void QueueOutbound_ChunkingAndPendingBytes_ShouldTrackState()
    {
        var c = new ClientConnection(ClientKind.Client)
        {
            OutMp = 100_000,
        };

        c.QueueOutbound(new byte[70_000]);

        c.OutPb.ShouldBe(70_000);
        c.OutNb.Count.ShouldBeGreaterThan(1);
        c.OutNb.Sum(chunk => chunk.Count).ShouldBe(70_000);
    }

    [Fact]
    public void FlushOutbound_WithoutServerOrConn_ShouldNoOpTrue()
    {
        var c = new ClientConnection(ClientKind.Client);
        c.QueueOutbound(Encoding.ASCII.GetBytes("hello"));

        c.FlushOutbound().ShouldBeTrue();
        c.OutPb.ShouldBe(5);
    }

    [Fact]
    public void HandleWriteTimeout_ClosePolicy_ShouldMarkClosed()
    {
        var c = new ClientConnection(ClientKind.Client)
        {
            OutWtp = WriteTimeoutPolicy.Close,
        };

        c.HandleWriteTimeout(0, 100, 1).ShouldBeTrue();
        c.Flags.IsSet(ClientFlags.ConnMarkedClosed).ShouldBeTrue();
        c.Flags.IsSet(ClientFlags.SkipFlushOnClose).ShouldBeTrue();
    }

    [Fact]
    public void HandleWriteTimeout_RetryPolicy_ShouldSetSlowConsumerFlag()
    {
        var c = new ClientConnection(ClientKind.Client)
        {
            OutWtp = WriteTimeoutPolicy.Retry,
        };

        c.HandleWriteTimeout(1, 100, 2).ShouldBeFalse();
        c.Flags.IsSet(ClientFlags.IsSlowConsumer).ShouldBeTrue();
    }

    [Fact]
    public void ProcessPubAndHeaderPubWrappers_ShouldPopulateParseContext()
    {
        var c = new ClientConnection(ClientKind.Client)
        {
            Headers = true,
        };

        c.ProcessPub(Encoding.ASCII.GetBytes("foo 5")).ShouldBeNull();
        Encoding.ASCII.GetString(c.ParseCtx.Pa.Subject!).ShouldBe("foo");
        c.ParseCtx.Pa.Size.ShouldBe(5);

        c.ProcessHeaderPub(Encoding.ASCII.GetBytes("foo 3 5"), null).ShouldBeNull();
        Encoding.ASCII.GetString(c.ParseCtx.Pa.Subject!).ShouldBe("foo");
        c.ParseCtx.Pa.HeaderSize.ShouldBe(3);
        c.ParseCtx.Pa.Size.ShouldBe(5);
    }

    [Fact]
    public void SplitArgParseSubAndProcessSub_ShouldCreateSubscriptions()
    {
        var tokens = ClientConnection.SplitArg(Encoding.ASCII.GetBytes("foo   queue  sid\r\n"));
        tokens.Count.ShouldBe(3);
        Encoding.ASCII.GetString(tokens[0]).ShouldBe("foo");
        Encoding.ASCII.GetString(tokens[1]).ShouldBe("queue");
        Encoding.ASCII.GetString(tokens[2]).ShouldBe("sid");

        var c = new ClientConnection(ClientKind.Client);
        c.ParseSub(Encoding.ASCII.GetBytes("foo queue sid"), noForward: true).ShouldBeNull();
        c.Subs.Count.ShouldBe(1);

        var result = c.ProcessSubEx(
            Encoding.ASCII.GetBytes("bar"),
            null,
            Encoding.ASCII.GetBytes("sid2"),
            noForward: false,
            si: false,
            rsi: false);
        result.err.ShouldBeNull();
        result.sub.ShouldNotBeNull();
        c.Subs.Count.ShouldBe(2);
    }
}