using Elsa.Workflows.Runtime.HealthChecks;
using Medallion.Threading;
using Microsoft.Extensions.Diagnostics.HealthChecks;
using NSubstitute;

namespace Elsa.Workflows.Runtime.UnitTests.HealthChecks;

public class ElsaDistributedLockHealthCheckTests
{
    private static readonly TimeSpan ExpectedLockAcquisitionTimeout = TimeSpan.FromSeconds(1);
    private readonly IDistributedLockProvider _distributedLockProvider = Substitute.For<IDistributedLockProvider>();
    private readonly IDistributedLock _distributedLock = Substitute.For<IDistributedLock>();
    private readonly ElsaDistributedLockHealthCheck _sut;

    public ElsaDistributedLockHealthCheckTests()
    {
        _distributedLockProvider.CreateLock(Arg.Any<string>()).Returns(_distributedLock);
        _distributedLock.TryAcquireAsync(Arg.Any<TimeSpan>(), Arg.Any<CancellationToken>())
            .Returns(new ValueTask<IDistributedSynchronizationHandle?>(Substitute.For<IDistributedSynchronizationHandle>()));
        _sut = new ElsaDistributedLockHealthCheck(_distributedLockProvider);
    }

    [Fact]
    public async Task ReturnsHealthyWhenProbeLockCanBeAcquired()
    {
        var result = await _sut.CheckHealthAsync(new HealthCheckContext());

        Assert.Equal(HealthStatus.Healthy, result.Status);
        Assert.Equal("distributed-locks", result.Data["category"]);
        _distributedLockProvider.Received(1).CreateLock(Arg.Is<string>(x => x.StartsWith("elsa-health-check-", StringComparison.Ordinal)));
        await _distributedLock.Received(1).TryAcquireAsync(ExpectedLockAcquisitionTimeout, Arg.Any<CancellationToken>());
    }

    [Fact]
    public async Task ReturnsDegradedWhenProbeLockCannotBeAcquired()
    {
        _distributedLock.TryAcquireAsync(Arg.Any<TimeSpan>(), Arg.Any<CancellationToken>())
            .Returns(new ValueTask<IDistributedSynchronizationHandle?>((IDistributedSynchronizationHandle?)null));

        var result = await _sut.CheckHealthAsync(new HealthCheckContext());

        Assert.Equal(HealthStatus.Degraded, result.Status);
        Assert.Equal("distributed-locks", result.Data["category"]);
    }

    [Fact]
    public async Task ReturnsUnhealthyWhenProviderThrows()
    {
        _distributedLockProvider.CreateLock(Arg.Any<string>()).Returns<IDistributedLock>(_ => throw new InvalidOperationException("lock backend unavailable"));

        var result = await _sut.CheckHealthAsync(new HealthCheckContext());

        Assert.Equal(HealthStatus.Unhealthy, result.Status);
        Assert.Equal("distributed-locks", result.Data["category"]);
    }
}