using WxAgent.Core;
using Xunit;

namespace WxAgent.Core.Tests;

public sealed class InterprocessCommandGateTests
{
    [Fact]
    public async Task SeparateInstancesShareAnExclusiveLease()
    {
        var path = Path.Combine(Path.GetTempPath(), "wx-gate-" + Guid.NewGuid(), "commands.lock");
        try
        {
            using var first = new InterprocessCommandGate(path);
            using var second = new InterprocessCommandGate(path);
            using var timeout = new CancellationTokenSource(TimeSpan.FromSeconds(5));
            await first.WaitAsync(timeout.Token);
            var waiting = second.WaitAsync(timeout.Token);
            Assert.False(waiting.IsCompleted);
            first.Release();
            await waiting;
            second.Release();
        }
        finally { Directory.Delete(Path.GetDirectoryName(path)!, recursive: true); }
    }

    [Fact]
    public async Task CancelledContentionDoesNotPoisonTheLocalQueue()
    {
        var path = Path.Combine(Path.GetTempPath(), "wx-gate-" + Guid.NewGuid(), "commands.lock");
        try
        {
            using var first = new InterprocessCommandGate(path);
            using var second = new InterprocessCommandGate(path);
            using var timeout = new CancellationTokenSource(TimeSpan.FromSeconds(5));
            await first.WaitAsync(timeout.Token);
            using var cancelled = new CancellationTokenSource(TimeSpan.FromMilliseconds(100));
            await Assert.ThrowsAnyAsync<OperationCanceledException>(() => second.WaitAsync(cancelled.Token));
            first.Release();
            await second.WaitAsync(timeout.Token);
            second.Release();
        }
        finally { Directory.Delete(Path.GetDirectoryName(path)!, recursive: true); }
    }

    [Fact]
    public async Task NonContentionIoErrorsAreNotRetried()
    {
        var path = Path.Combine(Path.GetTempPath(), "wx-gate-" + Guid.NewGuid(), "commands.lock");
        Directory.CreateDirectory(path); // A directory cannot be opened as the lock file.
        try
        {
            using var gate = new InterprocessCommandGate(path);
            using var timeout = new CancellationTokenSource(TimeSpan.FromSeconds(5));
            var error = await Record.ExceptionAsync(() => gate.WaitAsync(timeout.Token));
            Assert.True(error is IOException or UnauthorizedAccessException);
            Directory.Delete(path);
            await gate.WaitAsync(timeout.Token);
            gate.Release();
        }
        finally { Directory.Delete(Path.GetDirectoryName(path)!, recursive: true); }
    }
}