using Shouldly;
using Xunit;
using ZB.MOM.WW.OtOpcUa.Core.Abstractions;

namespace ZB.MOM.WW.OtOpcUa.Server.Tests.Alarms;

/// <summary>
///     PR B.3 — pins the routing decision DriverNodeManager makes when registering
///     an AlarmConditionState: drivers that implement <see cref="IAlarmSource"/>
///     get an acknowledger that calls AcknowledgeAsync (driver-native path); drivers
///     that don't fall back to the IWritable sub-attribute write.
/// </summary>
[Trait("Category", "Unit")]
public sealed class DriverAlarmSourceAcknowledgerRoutingTests
{
    [Fact]
    public void Driver_with_IAlarmSource_is_recognized()
    {
        IDriver driver = new FakeDriverWithAlarmSource("drv-1");
        (driver is IAlarmSource).ShouldBeTrue(
            "fakes that participate in the routing-test fixture must report IAlarmSource");
    }

    [Fact]
    public void Driver_without_IAlarmSource_falls_to_writable_path()
    {
        IDriver driver = new FakeDriverNoAlarmSource("drv-2");
        (driver is IAlarmSource).ShouldBeFalse(
            "drivers without IAlarmSource take the legacy DriverWritableAcknowledger path");
    }

    private sealed class FakeDriverWithAlarmSource(string id) : IDriver, IAlarmSource
    {
        public string DriverInstanceId { get; } = id;
        public string DriverType => "FakeAlarmSource";
        public Task InitializeAsync(string c, CancellationToken ct) => Task.CompletedTask;
        public Task ReinitializeAsync(string c, CancellationToken ct) => Task.CompletedTask;
        public Task ShutdownAsync(CancellationToken ct) => Task.CompletedTask;
        public DriverHealth GetHealth() => new(DriverState.Healthy, DateTime.UtcNow, null);
        public long GetMemoryFootprint() => 0;
        public Task FlushOptionalCachesAsync(CancellationToken ct) => Task.CompletedTask;

        public Task<IAlarmSubscriptionHandle> SubscribeAlarmsAsync(
            IReadOnlyList<string> sourceNodeIds, CancellationToken cancellationToken)
            => Task.FromResult<IAlarmSubscriptionHandle>(new FakeHandle("h"));
        public Task UnsubscribeAlarmsAsync(IAlarmSubscriptionHandle handle, CancellationToken cancellationToken)
            => Task.CompletedTask;
        public Task AcknowledgeAsync(
            IReadOnlyList<AlarmAcknowledgeRequest> acknowledgements, CancellationToken cancellationToken)
            => Task.CompletedTask;

        public event EventHandler<AlarmEventArgs>? OnAlarmEvent;
        private void NoUnusedWarning() => OnAlarmEvent?.Invoke(this, null!);
    }

    private sealed class FakeDriverNoAlarmSource(string id) : IDriver
    {
        public string DriverInstanceId { get; } = id;
        public string DriverType => "FakeNoAlarmSource";
        public Task InitializeAsync(string c, CancellationToken ct) => Task.CompletedTask;
        public Task ReinitializeAsync(string c, CancellationToken ct) => Task.CompletedTask;
        public Task ShutdownAsync(CancellationToken ct) => Task.CompletedTask;
        public DriverHealth GetHealth() => new(DriverState.Healthy, DateTime.UtcNow, null);
        public long GetMemoryFootprint() => 0;
        public Task FlushOptionalCachesAsync(CancellationToken ct) => Task.CompletedTask;
    }

    private sealed class FakeHandle(string id) : IAlarmSubscriptionHandle
    {
        public string DiagnosticId { get; } = id;
    }
}