using Akka.Actor;
using Akka.TestKit.Xunit2;
using Microsoft.Extensions.Logging.Abstractions;
using Microsoft.Extensions.Options;
using ScadaLink.Commons.Messages.Deployment;
using ScadaLink.Commons.Messages.Notification;
using ScadaLink.Commons.Types.Notifications;

namespace ScadaLink.Communication.Tests;

/// <summary>
/// WP-2: Tests for CommunicationService initialization and state.
/// </summary>
public class CommunicationServiceTests : TestKit
{
    [Fact]
    public async Task BeforeInitialization_ThrowsOnUsage()
    {
        var options = Options.Create(new CommunicationOptions());
        var logger = NullLogger<CommunicationService>.Instance;
        var service = new CommunicationService(options, logger);

        // CommunicationService requires SetCommunicationActor before use
        await Assert.ThrowsAsync<InvalidOperationException>(() =>
            service.DeployInstanceAsync("site1",
                new DeployInstanceCommand(
                    "dep1", "inst1", "hash1", "{}", "admin", DateTimeOffset.UtcNow)));
    }

    [Fact]
    public void UnsubscribeDebugView_IsTellNotAsk()
    {
        // Verify the method signature is void (fire-and-forget Tell pattern)
        var method = typeof(CommunicationService).GetMethod("UnsubscribeDebugView");
        Assert.NotNull(method);
        Assert.Equal(typeof(void), method!.ReturnType);
    }

    // ── DeploymentManager-006: query-the-site-before-redeploy ──

    [Fact]
    public async Task QueryDeploymentStateAsync_BeforeInitialization_Throws()
    {
        var service = new CommunicationService(
            Options.Create(new CommunicationOptions()),
            NullLogger<CommunicationService>.Instance);

        await Assert.ThrowsAsync<InvalidOperationException>(() =>
            service.QueryDeploymentStateAsync("site1",
                new DeploymentStateQueryRequest("corr-1", "inst1", DateTimeOffset.UtcNow)));
    }

    [Fact]
    public async Task QueryDeploymentStateAsync_SendsEnvelopeAndReturnsResponse()
    {
        // The query must be dispatched as a SiteEnvelope over the existing
        // command/control transport, exactly like other site-directed commands,
        // and the typed response returned to the caller.
        var service = new CommunicationService(
            Options.Create(new CommunicationOptions()),
            NullLogger<CommunicationService>.Instance);

        // A probe stands in for CentralCommunicationActor: it asserts the
        // envelope shape and replies with a typed response.
        var commActor = Sys.ActorOf(Props.Create(() => new EchoStateQueryActor()));
        service.SetCommunicationActor(commActor);

        var request = new DeploymentStateQueryRequest("corr-9", "QueriedInst", DateTimeOffset.UtcNow);
        var response = await service.QueryDeploymentStateAsync("site-a", request);

        Assert.Equal("corr-9", response.CorrelationId);
        Assert.Equal("QueriedInst", response.InstanceUniqueName);
        Assert.True(response.IsDeployed);
        Assert.Equal("sha256:applied", response.AppliedRevisionHash);
    }

    // ── Notification Outbox: central-side outbox actor calls ──

    [Fact]
    public async Task QueryNotificationOutboxAsync_BeforeOutboxSet_Throws()
    {
        var service = new CommunicationService(
            Options.Create(new CommunicationOptions()),
            NullLogger<CommunicationService>.Instance);

        await Assert.ThrowsAsync<InvalidOperationException>(() =>
            service.QueryNotificationOutboxAsync(
                new NotificationOutboxQueryRequest(
                    "corr-1", null, null, null, null, false, null, null, null, 1, 50)));
    }

    [Fact]
    public async Task RetryNotificationAsync_BeforeOutboxSet_Throws()
    {
        var service = new CommunicationService(
            Options.Create(new CommunicationOptions()),
            NullLogger<CommunicationService>.Instance);

        await Assert.ThrowsAsync<InvalidOperationException>(() =>
            service.RetryNotificationAsync(new RetryNotificationRequest("corr-1", "n1")));
    }

    [Fact]
    public async Task DiscardNotificationAsync_BeforeOutboxSet_Throws()
    {
        var service = new CommunicationService(
            Options.Create(new CommunicationOptions()),
            NullLogger<CommunicationService>.Instance);

        await Assert.ThrowsAsync<InvalidOperationException>(() =>
            service.DiscardNotificationAsync(new DiscardNotificationRequest("corr-1", "n1")));
    }

    [Fact]
    public async Task GetNotificationKpisAsync_BeforeOutboxSet_Throws()
    {
        var service = new CommunicationService(
            Options.Create(new CommunicationOptions()),
            NullLogger<CommunicationService>.Instance);

        await Assert.ThrowsAsync<InvalidOperationException>(() =>
            service.GetNotificationKpisAsync(new NotificationKpiRequest("corr-1")));
    }

    [Fact]
    public async Task QueryNotificationOutboxAsync_AsksOutboxProxyDirectly()
    {
        // The outbox actor is central-local: the request must be Asked directly
        // to the outbox proxy (no SiteEnvelope wrapping).
        var service = new CommunicationService(
            Options.Create(new CommunicationOptions()),
            NullLogger<CommunicationService>.Instance);
        var probe = CreateTestProbe();
        service.SetNotificationOutbox(probe.Ref);

        var request = new NotificationOutboxQueryRequest(
            "corr-q", "Pending", null, null, null, true, "alarm", null, null, 2, 25);
        var task = service.QueryNotificationOutboxAsync(request);

        var received = probe.ExpectMsg<NotificationOutboxQueryRequest>();
        Assert.Same(request, received);
        var reply = new NotificationOutboxQueryResponse(
            "corr-q", true, null, Array.Empty<NotificationSummary>(), 0);
        probe.Reply(reply);

        Assert.Same(reply, await task);
    }

    [Fact]
    public async Task RetryNotificationAsync_AsksOutboxProxyDirectly()
    {
        var service = new CommunicationService(
            Options.Create(new CommunicationOptions()),
            NullLogger<CommunicationService>.Instance);
        var probe = CreateTestProbe();
        service.SetNotificationOutbox(probe.Ref);

        var request = new RetryNotificationRequest("corr-r", "n-7");
        var task = service.RetryNotificationAsync(request);

        var received = probe.ExpectMsg<RetryNotificationRequest>();
        Assert.Same(request, received);
        var reply = new RetryNotificationResponse("corr-r", true, null);
        probe.Reply(reply);

        Assert.Same(reply, await task);
    }

    [Fact]
    public async Task DiscardNotificationAsync_AsksOutboxProxyDirectly()
    {
        var service = new CommunicationService(
            Options.Create(new CommunicationOptions()),
            NullLogger<CommunicationService>.Instance);
        var probe = CreateTestProbe();
        service.SetNotificationOutbox(probe.Ref);

        var request = new DiscardNotificationRequest("corr-d", "n-9");
        var task = service.DiscardNotificationAsync(request);

        var received = probe.ExpectMsg<DiscardNotificationRequest>();
        Assert.Same(request, received);
        var reply = new DiscardNotificationResponse("corr-d", false, "already delivered");
        probe.Reply(reply);

        var result = await task;
        Assert.Same(reply, result);
        Assert.False(result.Success);
    }

    [Fact]
    public async Task GetNotificationKpisAsync_AsksOutboxProxyDirectly()
    {
        var service = new CommunicationService(
            Options.Create(new CommunicationOptions()),
            NullLogger<CommunicationService>.Instance);
        var probe = CreateTestProbe();
        service.SetNotificationOutbox(probe.Ref);

        var request = new NotificationKpiRequest("corr-k");
        var task = service.GetNotificationKpisAsync(request);

        var received = probe.ExpectMsg<NotificationKpiRequest>();
        Assert.Same(request, received);
        var reply = new NotificationKpiResponse("corr-k", true, null, 3, 1, 0, 12, TimeSpan.FromMinutes(5));
        probe.Reply(reply);

        var result = await task;
        Assert.Same(reply, result);
        Assert.Equal(3, result.QueueDepth);
    }

    [Fact]
    public async Task GetPerSiteNotificationKpisAsync_AsksOutboxProxyDirectly()
    {
        var service = new CommunicationService(
            Options.Create(new CommunicationOptions()),
            NullLogger<CommunicationService>.Instance);
        var probe = CreateTestProbe();
        service.SetNotificationOutbox(probe.Ref);

        var request = new PerSiteNotificationKpiRequest("corr-ps");
        var task = service.GetPerSiteNotificationKpisAsync(request);

        var received = probe.ExpectMsg<PerSiteNotificationKpiRequest>();
        Assert.Same(request, received);
        var reply = new PerSiteNotificationKpiResponse(
            "corr-ps", true, null,
            new[] { new SiteNotificationKpiSnapshot("plant-a", 2, 0, 0, 5, null) });
        probe.Reply(reply);

        var result = await task;
        Assert.Same(reply, result);
        Assert.True(result.Success);
        Assert.Single(result.Sites);
        Assert.Equal("plant-a", result.Sites[0].SourceSiteId);
    }

    /// <summary>
    /// Stand-in for CentralCommunicationActor: verifies the message is wrapped
    /// in a SiteEnvelope targeting the requested site and replies with a typed
    /// DeploymentStateQueryResponse.
    /// </summary>
    private class EchoStateQueryActor : ReceiveActor
    {
        public EchoStateQueryActor()
        {
            Receive<SiteEnvelope>(env =>
            {
                if (env is { SiteId: "site-a", Message: DeploymentStateQueryRequest req })
                {
                    Sender.Tell(new DeploymentStateQueryResponse(
                        req.CorrelationId, req.InstanceUniqueName, true,
                        "dep-applied", "sha256:applied", DateTimeOffset.UtcNow));
                }
            });
        }
    }
}
