using ErsatzTV.Controllers;
using ErsatzTV.Core.Domain;
using ErsatzTV.Core.Interfaces.Streaming;
using ErsatzTV.Core.Streaming;
using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Mvc;
using Microsoft.AspNetCore.Routing;
using Microsoft.Extensions.DependencyInjection;
using NSubstitute;
using NUnit.Framework;
using Shouldly;

namespace ErsatzTV.Tests.Controllers;

[TestFixture]
public class TrackedFileStreamResultTests
{
    [Test]
    public async Task Should_Track_Session_Only_While_Result_Executes()
    {
        var tracker = new DirectStreamSessionTracker();
        var stream = new BlockingReadStream();
        TrackedFileStreamResult result = new(
            stream,
            "video/mp2t",
            tracker,
            "1",
            StreamingMode.TransportStream);

        ActionContext context = GetActionContext();

        tracker.IsActive("1").ShouldBeFalse();

        Task execute = result.ExecuteResultAsync(context);
        await stream.WaitForRead();

        tracker.IsActive("1").ShouldBeTrue();
        tracker.GetViewerCount("1").ShouldBe(1);

        stream.Complete();
        await execute;

        tracker.IsActive("1").ShouldBeFalse();
        tracker.GetViewerCount("1").ShouldBe(0);
    }

    [Test]
    public async Task Should_Remove_Session_When_Response_Stream_Fails()
    {
        var tracker = new DirectStreamSessionTracker();
        TrackedFileStreamResult result = new(
            new ThrowingReadStream(new IOException("stream failed")),
            "video/mp2t",
            tracker,
            "1",
            StreamingMode.HttpLiveStreamingDirect);

        Func<Task> execute = () => result.ExecuteResultAsync(GetActionContext());

        await execute.ShouldThrowAsync<IOException>();

        tracker.IsActive("1").ShouldBeFalse();
        tracker.GetViewerCount("1").ShouldBe(0);
    }

    [Test]
    public async Task Should_Remove_Session_When_Response_Stream_Is_Aborted()
    {
        var tracker = new DirectStreamSessionTracker();
        TrackedFileStreamResult result = new(
            new ThrowingReadStream(new OperationCanceledException("client aborted")),
            "video/mp2t",
            tracker,
            "1",
            StreamingMode.HttpLiveStreamingDirect);

        await result.ExecuteResultAsync(GetActionContext());

        tracker.IsActive("1").ShouldBeFalse();
        tracker.GetViewerCount("1").ShouldBe(0);
    }

    [Test]
    public async Task Should_Not_Track_Session_For_Head_Request()
    {
        IDirectStreamSessionTracker tracker = Substitute.For<IDirectStreamSessionTracker>();
        var stream = new BlockingReadStream();
        TrackedFileStreamResult result = new(
            stream,
            "video/mp2t",
            tracker,
            "1",
            StreamingMode.TransportStream);

        await result.ExecuteResultAsync(GetActionContext(HttpMethods.Head));

        tracker.DidNotReceive().Register(Arg.Any<string>(), Arg.Any<StreamingMode>());
    }

    private static ActionContext GetActionContext(string method = "GET")
    {
        var httpContext = new DefaultHttpContext();
        httpContext.Request.Method = method;
        httpContext.RequestServices = new ServiceCollection()
            .AddLogging()
            .AddControllers()
            .Services
            .BuildServiceProvider();
        httpContext.Response.Body = new MemoryStream();

        return new ActionContext(httpContext, new RouteData(), new Microsoft.AspNetCore.Mvc.Abstractions.ActionDescriptor());
    }

    private sealed class BlockingReadStream : Stream
    {
        private readonly TaskCompletionSource _continue = new(TaskCreationOptions.RunContinuationsAsynchronously);
        private readonly TaskCompletionSource _readStarted = new(TaskCreationOptions.RunContinuationsAsynchronously);

        public override bool CanRead => true;
        public override bool CanSeek => false;
        public override bool CanWrite => false;
        public override long Length => 0;
        public override long Position { get; set; }

        public Task WaitForRead() => _readStarted.Task.WaitAsync(TimeSpan.FromSeconds(5));

        public void Complete() => _continue.SetResult();

        public override ValueTask<int> ReadAsync(Memory<byte> buffer, CancellationToken cancellationToken = default)
        {
            _readStarted.TrySetResult();
            return ReadAfterContinue();
        }

        public override Task<int> ReadAsync(byte[] buffer, int offset, int count, CancellationToken cancellationToken) =>
            ReadAsync(buffer.AsMemory(offset, count), cancellationToken).AsTask();

        public override int Read(byte[] buffer, int offset, int count) => throw new NotSupportedException();

        public override void Flush()
        {
        }

        public override long Seek(long offset, SeekOrigin origin) => throw new NotSupportedException();

        public override void SetLength(long value) => throw new NotSupportedException();

        public override void Write(byte[] buffer, int offset, int count) => throw new NotSupportedException();

        private async ValueTask<int> ReadAfterContinue()
        {
            await _continue.Task;
            return 0;
        }
    }

    private sealed class ThrowingReadStream(Exception exception) : Stream
    {
        public override bool CanRead => true;
        public override bool CanSeek => false;
        public override bool CanWrite => false;
        public override long Length => 0;
        public override long Position { get; set; }

        public override ValueTask<int> ReadAsync(Memory<byte> buffer, CancellationToken cancellationToken = default) =>
            ValueTask.FromException<int>(exception);

        public override Task<int> ReadAsync(byte[] buffer, int offset, int count, CancellationToken cancellationToken) =>
            ReadAsync(buffer.AsMemory(offset, count), cancellationToken).AsTask();

        public override int Read(byte[] buffer, int offset, int count) => throw exception;

        public override void Flush()
        {
        }

        public override long Seek(long offset, SeekOrigin origin) => throw new NotSupportedException();

        public override void SetLength(long value) => throw new NotSupportedException();

        public override void Write(byte[] buffer, int offset, int count) => throw new NotSupportedException();
    }
}