using Luna.Channels.Abstractions;
using Luna.Channels.Tests.Stubs;
using Luna.Core.Abstractions;
using Luna.Shared;
using Microsoft.Extensions.Logging;
using Moq;

namespace Luna.Channels.Tests;

[TestFixture]
[Category("Unit")]
public class ChannelManagerTests
{
    private readonly Mock<ILogger<ChannelManager>> loggerMock = new();
    
    private static Mock<IChannel> BuildChannelMock(string id)
    {
        var mock = new Mock<IChannel>();
        mock.Setup(c => c.ChannelId).Returns(id);
        mock.Setup(c => c.ChannelType).Returns("test");
        mock.Setup(c => c.DisplayName).Returns($"Channel {id}");
        mock.Setup(c => c.IsConnected).Returns(true);
        mock.Setup(c => c.SendStreamingMessageAsync(
                It.IsAny<IAsyncEnumerable<ChatStreamUpdate>>(),
                It.IsAny<CancellationToken>()))
            .Returns(Task.CompletedTask);
        return mock;
    }

    private static ChannelMessage BuildMessage(string content = "Hello") =>
        new ChannelMessage(
            Guid.NewGuid().ToString(),
            Guid.NewGuid().ToString(),
            "sender-1",
            "Sender Name",
            content,
            DateTimeOffset.UtcNow);

    [Test]
    public void RegisterChannel_AddsToRegistry_GetChannel_ReturnsIt()
    {
        var sessionManagerMock = new Mock<ISessionManager>();
        var sut = new ChannelManager(sessionManagerMock.Object, loggerMock.Object);
        var mockChannel = BuildChannelMock("ch-reg-1");

        sut.RegisterChannel(mockChannel.Object);
        var result = sut.GetChannel("ch-reg-1");

        Assert.That(result, Is.SameAs(mockChannel.Object));
    }

    [Test]
    public void RegisterChannel_DuplicateId_Throws_InvalidOperationException()
    {
        var sessionManagerMock = new Mock<ISessionManager>();
        var sut = new ChannelManager(sessionManagerMock.Object, loggerMock.Object);
        var mockChannel = BuildChannelMock("ch-dup-1");

        sut.RegisterChannel(mockChannel.Object);

        Assert.That(
            () => sut.RegisterChannel(mockChannel.Object),
            Throws.TypeOf<InvalidOperationException>());
    }

    [Test]
    public void UnregisterChannel_RemovesChannel_GetChannel_ReturnsNull()
    {
        var sessionManagerMock = new Mock<ISessionManager>();
        var sut = new ChannelManager(sessionManagerMock.Object, loggerMock.Object);
        var mockChannel = BuildChannelMock("ch-rem-1");

        sut.RegisterChannel(mockChannel.Object);
        sut.UnregisterChannel("ch-rem-1");
        var result = sut.GetChannel("ch-rem-1");

        Assert.That(result, Is.Null);
    }

    [Test]
    public void UnregisterChannel_UnknownId_NoOp()
    {
        var sessionManagerMock = new Mock<ISessionManager>();
        var sut = new ChannelManager(sessionManagerMock.Object, loggerMock.Object);

        Assert.That(() => sut.UnregisterChannel("does-not-exist"), Throws.Nothing);
    }

    [Test]
    public void GetAllChannels_ReturnsAllRegistered()
    {
        var sessionManagerMock = new Mock<ISessionManager>();
        var sut = new ChannelManager(sessionManagerMock.Object, loggerMock.Object);

        for (var i = 0; i < 3; i++)
            sut.RegisterChannel(new CliChannelStub { ChannelId = i.ToString() });

        var all = sut.GetAllChannels();

        Assert.That(all.Count, Is.EqualTo(3));
    }

    [Test]
    public async Task MessageReceived_Routes_To_SessionManager()
    {
        var mockSession = new Mock<ISessionManager>();
        mockSession
            .Setup(s => s.RouteMessagesAsync(
                It.IsAny<string>(),
                It.IsAny<string>(),
                It.IsAny<string>(),
                It.IsAny<CancellationToken>()))
            .Returns(AsyncEnumerable.Empty<ChatStreamUpdate>());

        var sut = new ChannelManager(mockSession.Object, loggerMock.Object);
        var mockChannel = BuildChannelMock("ch-route-1");

        sut.RegisterChannel(mockChannel.Object);

        var message = BuildMessage("Hello from channel");
        mockChannel.Raise(c => c.MessageReceived += null, mockChannel.Object,
            new ChannelMessageReceivedEventArgs
            {
                Message = message,
                Channel = mockChannel.Object
            });

        await Task.Delay(100);

        mockSession.Verify(
            s => s.RouteMessagesAsync(
                message.Content,
                message.ConversationId,
                It.IsAny<string>(),
                It.IsAny<CancellationToken>()),
            Times.Once);
    }

    [Test]
    public async Task MessageReceived_Pipes_StreamingResponse_To_Channel()
    {
        async IAsyncEnumerable<ChatStreamUpdate> FakeStreamAsync()
        {
            yield return new ChatStreamUpdate(ChatStreamUpdateType.Text, "AI reply", null, false);
            yield return new ChatStreamUpdate(ChatStreamUpdateType.Complete, null, null, true);
        }

        var mockSession = new Mock<ISessionManager>();
        mockSession
            .Setup(s => s.RouteMessagesAsync(
                It.IsAny<string>(),
                It.IsAny<string>(),
                It.IsAny<string>(),
                It.IsAny<CancellationToken>()))
            .Returns(FakeStreamAsync());

        var sut = new ChannelManager(mockSession.Object, loggerMock.Object);
        var mockChannel = BuildChannelMock("ch-stream-1");

        sut.RegisterChannel(mockChannel.Object);

        await mockChannel.RaiseAsync(c => c.MessageReceived += null, mockChannel.Object,
            new ChannelMessageReceivedEventArgs
            {
                Message = BuildMessage("stream test"),
                Channel = mockChannel.Object
            });

        await Task.Delay(200);

        mockChannel.Verify(
            c => c.SendStreamingMessageAsync(
                It.IsAny<IAsyncEnumerable<ChatStreamUpdate>>(),
                It.IsAny<CancellationToken>()),
            Times.Once);
    }

    [Test]
    public async Task MessageReceived_IsHandled_True_SkipsRouting()
    {
        var mockSession = new Mock<ISessionManager>();

        var sut = new ChannelManager(mockSession.Object, loggerMock.Object);
        var mockChannel = BuildChannelMock("ch-handled-1");

        sut.RegisterChannel(mockChannel.Object);

        await mockChannel.RaiseAsync(c => c.MessageReceived += null, mockChannel.Object,
            new ChannelMessageReceivedEventArgs
            {
                Message = BuildMessage("already handled"),
                Channel = mockChannel.Object,
                IsHandled = true
            });

        await Task.Delay(100);

        mockSession.Verify(
            s => s.RouteMessagesAsync(
                It.IsAny<string>(),
                It.IsAny<string>(),
                It.IsAny<string>(),
                It.IsAny<CancellationToken>()),
            Times.Never);
    }

    [Test]
    public async Task RouteMessagesAsync_Throws_ChannelNotDisconnected()
    {
        var mockSession = new Mock<ISessionManager>();
        mockSession
            .Setup(s => s.RouteMessagesAsync(
                It.IsAny<string>(),
                It.IsAny<string>(),
                It.IsAny<string>(),
                It.IsAny<CancellationToken>()))
            .Throws(new Exception("Simulated routing failure"));

        var sut = new ChannelManager(mockSession.Object, loggerMock.Object);
        var mockChannel = BuildChannelMock("ch-err-1");
        mockChannel.Setup(c => c.IsConnected).Returns(true);

        sut.RegisterChannel(mockChannel.Object);

        Assert.That(
            async () =>
            {
                await mockChannel.RaiseAsync(c => c.MessageReceived += null, mockChannel.Object,
                    new ChannelMessageReceivedEventArgs
                    {
                        Message = BuildMessage("error trigger"),
                        Channel = mockChannel.Object
                    });
                await Task.Delay(200);
            },
            Throws.Nothing);

        Assert.That(mockChannel.Object.IsConnected, Is.True);
    }
}