using System;
using System.Threading;
using System.Threading.Tasks;
using FluentAssertions;
using Xunit;
using ZB.MOM.WW.LmxProxy.Host.MxAccess;

namespace ZB.MOM.WW.LmxProxy.Host.Tests.MxAccess
{
    public class StaDispatchThreadTests
    {
        [Fact]
        public async Task DispatchAsync_ExecutesOnStaThread()
        {
            using var sta = new StaDispatchThread("Test-STA");
            var threadId = await sta.DispatchAsync(() => Thread.CurrentThread.ManagedThreadId);
            threadId.Should().NotBe(Thread.CurrentThread.ManagedThreadId);
        }

        [Fact]
        public async Task DispatchAsync_ReturnsResult()
        {
            using var sta = new StaDispatchThread("Test-STA");
            var result = await sta.DispatchAsync(() => 42);
            result.Should().Be(42);
        }

        [Fact]
        public async Task DispatchAsync_PropagatesException()
        {
            using var sta = new StaDispatchThread("Test-STA");
            Func<Task> act = () => sta.DispatchAsync<int>(() => throw new InvalidOperationException("test error"));
            await act.Should().ThrowAsync<InvalidOperationException>().WithMessage("test error");
        }

        [Fact]
        public async Task DispatchAsync_Action_Completes()
        {
            using var sta = new StaDispatchThread("Test-STA");
            int value = 0;
            await sta.DispatchAsync(() => { value = 99; });
            value.Should().Be(99);
        }

        [Fact]
        public void Dispose_CompletesGracefully()
        {
            var sta = new StaDispatchThread("Test-STA");
            sta.Dispose(); // Should not throw
        }

        [Fact]
        public void DispatchAfterDispose_ThrowsObjectDisposedException()
        {
            var sta = new StaDispatchThread("Test-STA");
            sta.Dispose();
            Func<Task> act = () => sta.DispatchAsync(() => 42);
            act.Should().ThrowAsync<ObjectDisposedException>();
        }

        [Fact]
        public async Task MultipleDispatches_ExecuteInOrder()
        {
            using var sta = new StaDispatchThread("Test-STA");
            var results = new System.Collections.Concurrent.ConcurrentBag<int>();

            var tasks = new Task[10];
            for (int i = 0; i < 10; i++)
            {
                int idx = i;
                tasks[i] = sta.DispatchAsync(() => { results.Add(idx); });
            }

            await Task.WhenAll(tasks);
            results.Count.Should().Be(10);
        }

        [Fact]
        public async Task StaThread_HasStaApartmentState()
        {
            using var sta = new StaDispatchThread("Test-STA");
            var apartmentState = await sta.DispatchAsync(() => Thread.CurrentThread.GetApartmentState());
            apartmentState.Should().Be(ApartmentState.STA);
        }
    }
}