using Akka.Actor;
using Microsoft.Extensions.Logging.Abstractions;
using Shouldly;
using Xunit;
using ZB.MOM.WW.OtOpcUa.Runtime.Drivers;
using ZB.MOM.WW.OtOpcUa.Runtime.Tests.Harness;

namespace ZB.MOM.WW.OtOpcUa.Runtime.Tests.Drivers;

/// <summary>
///     Verifies the <see cref="ActorNodeWriteGateway"/> adapter: it implements the Commons
///     <c>IOpcUaNodeWriteGateway</c> by lazily resolving the <see cref="DriverHostActor"/> and Asking it a
///     <see cref="DriverHostActor.RouteNodeWrite"/>, translating the actor's
///     <see cref="DriverHostActor.NodeWriteResult"/> reply into a Commons <c>NodeWriteOutcome</c>. A
///     <c>TestProbe</c> stands in for the DriverHostActor (passed via <c>resolveDriverHost</c>) so the
///     gateway can be driven without the full driver harness.
/// </summary>
public sealed class ActorNodeWriteGatewayTests : RuntimeActorTestBase
{
    /// <summary>Probe receives the RouteNodeWrite and replies success → the outcome is (true, null).</summary>
    [Fact]
    public async Task Success_reply_maps_to_successful_outcome()
    {
        var probe = CreateTestProbe();
        var gateway = new ActorNodeWriteGateway(resolveDriverHost: () => probe.Ref, NullLogger.Instance);

        var writeTask = gateway.WriteAsync("eq-1/speed", 123.0, CancellationToken.None);

        var routed = probe.ExpectMsg<DriverHostActor.RouteNodeWrite>(TimeSpan.FromSeconds(5));
        routed.NodeId.ShouldBe("eq-1/speed");
        routed.Value.ShouldBe(123.0);
        probe.Reply(new DriverHostActor.NodeWriteResult(true, null));

        var outcome = await writeTask;
        outcome.Success.ShouldBeTrue();
        outcome.Reason.ShouldBeNull();
    }

    /// <summary>Probe replies failure → the outcome carries the same (false, reason) verbatim.</summary>
    [Fact]
    public async Task Failure_reply_maps_to_failure_outcome_with_reason()
    {
        var probe = CreateTestProbe();
        var gateway = new ActorNodeWriteGateway(resolveDriverHost: () => probe.Ref, NullLogger.Instance);

        var writeTask = gateway.WriteAsync("eq-1/speed", 123.0, CancellationToken.None);

        probe.ExpectMsg<DriverHostActor.RouteNodeWrite>(TimeSpan.FromSeconds(5));
        probe.Reply(new DriverHostActor.NodeWriteResult(false, "not primary"));

        var outcome = await writeTask;
        outcome.Success.ShouldBeFalse();
        outcome.Reason.ShouldBe("not primary");
    }

    /// <summary>The probe never replies; a short Ask timeout makes the gateway fast-fail with a negative,
    /// non-null-reason outcome rather than hanging.</summary>
    [Fact]
    public async Task No_reply_within_timeout_maps_to_negative_outcome()
    {
        var probe = CreateTestProbe();
        var gateway = new ActorNodeWriteGateway(
            resolveDriverHost: () => probe.Ref, NullLogger.Instance,
            askTimeout: TimeSpan.FromMilliseconds(200));

        var outcome = await gateway.WriteAsync("eq-1/speed", 123.0, CancellationToken.None);

        outcome.Success.ShouldBeFalse();
        outcome.Reason.ShouldNotBeNull();
        outcome.Reason.ShouldBe("write timeout");
    }

    /// <summary>When no DriverHostActor is registered (resolver returns null), the gateway short-circuits
    /// to (false, "writes unavailable") and never messages any actor.</summary>
    [Fact]
    public async Task No_actor_registered_maps_to_writes_unavailable()
    {
        var gateway = new ActorNodeWriteGateway(resolveDriverHost: () => null, NullLogger.Instance);

        var outcome = await gateway.WriteAsync("eq-1/speed", 123.0, CancellationToken.None);

        outcome.Success.ShouldBeFalse();
        outcome.Reason.ShouldBe("writes unavailable");
    }
}