using Akka.Actor;
using Microsoft.AspNetCore.SignalR;
using Microsoft.Extensions.DependencyInjection;
using Moq;
using Shouldly;
using Xunit;
using ZB.MOM.WW.OtOpcUa.AdminUI.Hubs;
using ZB.MOM.WW.OtOpcUa.Commons.Interfaces;
using ZB.MOM.WW.OtOpcUa.Commons.Messages.Admin;
using ZB.MOM.WW.OtOpcUa.Commons.Messages.Drivers;
using ZB.MOM.WW.OtOpcUa.Configuration.Entities;
using ZB.MOM.WW.OtOpcUa.Configuration.Enums;

namespace ZB.MOM.WW.OtOpcUa.Host.IntegrationTests;

/// <summary>
///     E2E integration coverage for the <c>ReconnectDriver</c> command path through
///     <see cref="IAdminOperationsClient"/>.
///
///     <para>The first two tests verify the message round-trip through the
///     <c>AdminOperationsActor</c> singleton against a non-deployed instance id: the command is
///     accepted, persisted as a <c>ConfigEdit</c> audit row, and the reply carries
///     <c>Ok = true</c> with the matching <c>CorrelationId</c>.</para>
///
///     <para><see cref="Reconnect_DeployedDriver_TransitionsThroughReconnectingBackToHealthy"/>
///     goes the full distance: it deploys a real driver (via the opt-in
///     <see cref="FakeReconnectDriverFactory"/> wired into the harness) so the
///     <c>DriverHostActor</c> spawns a managed <c>DriverInstanceActor</c>, then drives the
///     end-to-end reconnect path —
///     <c>ReconnectDriver → AdminOperationsActor → DriverHostActor.HandleReconnectDriver →
///     DriverInstanceActor.ForceReconnect (FSM) → PublishHealthSnapshot → driver-health DPS topic →
///     DriverStatusSignalRBridge → snapshot store / hub push</c> — and asserts the published health
///     transitions Healthy → Reconnecting → Healthy.</para>
/// </summary>
[Trait("Category", "Integration")]
public sealed class DriverReconnectE2eTests
{
    private static CancellationToken Ct => TestContext.Current.CancellationToken;

    /// <summary>
    ///     Verifies that a <see cref="ReconnectDriver"/> message dispatched through
    ///     <see cref="IAdminOperationsClient.AskAsync{T}"/> returns a
    ///     <see cref="ReconnectDriverResult"/> with <c>Ok = true</c> and the matching
    ///     correlation ID, confirming the cluster-singleton round-trip works end-to-end.
    ///
    ///     <para>The instance ID used here ("reconnect-e2e-nonexistent") does not correspond
    ///     to a deployed driver, so no <c>DriverInstanceActor</c> will act on the DPS
    ///     broadcast — the test is validating the command ingestion and reply path only.</para>
    /// </summary>
    [Fact]
    public async Task Reconnect_RoundTrip_ReturnsOk()
    {
        await using var harness = await TwoNodeClusterHarness.StartAsync();
        await using var scope = harness.NodeA.Services.CreateAsyncScope();
        var client = scope.ServiceProvider.GetRequiredService<IAdminOperationsClient>();

        var correlationId = Guid.NewGuid();
        var msg = new ReconnectDriver(
            ClusterId: "cluster-e2e-test",
            DriverInstanceId: "reconnect-e2e-nonexistent",
            ActorByUserName: "e2e-test-runner",
            CorrelationId: correlationId);

        var result = await client.AskAsync<ReconnectDriverResult>(msg, Ct);

        result.CorrelationId.ShouldBe(correlationId);
        result.Ok.ShouldBeTrue($"ReconnectDriver round-trip failed: {result.Message}");
        result.Message.ShouldBeNull();
    }

    /// <summary>
    ///     Verifies that a second <see cref="ReconnectDriver"/> for the same instance ID
    ///     is also accepted (idempotent at the actor layer — the actor simply re-broadcasts
    ///     to DPS and writes another <c>ConfigEdit</c> row).
    /// </summary>
    [Fact]
    public async Task Reconnect_IsIdempotent_SecondCallAlsoReturnsOk()
    {
        await using var harness = await TwoNodeClusterHarness.StartAsync();
        await using var scope = harness.NodeA.Services.CreateAsyncScope();
        var client = scope.ServiceProvider.GetRequiredService<IAdminOperationsClient>();

        const string instanceId = "reconnect-idempotency-test";

        var first = new ReconnectDriver("cluster-1", instanceId, "runner", Guid.NewGuid());
        var second = new ReconnectDriver("cluster-1", instanceId, "runner", Guid.NewGuid());

        var r1 = await client.AskAsync<ReconnectDriverResult>(first, Ct);
        var r2 = await client.AskAsync<ReconnectDriverResult>(second, Ct);

        r1.Ok.ShouldBeTrue($"First call failed: {r1.Message}");
        r2.Ok.ShouldBeTrue($"Second call failed: {r2.Message}");
        r1.CorrelationId.ShouldBe(first.CorrelationId);
        r2.CorrelationId.ShouldBe(second.CorrelationId);
    }

    private const string ClusterId = "RECONNECT-E2E";
    private const string DriverId = "drv-modbus";

    /// <summary>
    ///     Full-stack reconnect: deploys a real driver (the in-process
    ///     <see cref="FakeReconnectDriverFactory"/>), proves it reaches Healthy on the driver-health DPS
    ///     topic, simulates a lost connection (<see cref="FakeReconnectDriver.ReportReconnecting"/>), issues
    ///     a <see cref="ReconnectDriver"/> through <see cref="IAdminOperationsClient"/>, and asserts the
    ///     published health walks Healthy → Reconnecting → Healthy — captured at the
    ///     <see cref="DriverStatusSignalRBridge"/> hub-push seam. Confirms the operator Reconnect threads
    ///     the whole cluster path and genuinely re-initialises the driver (<c>InitializeCount ≥ 2</c>).
    /// </summary>
    [Fact]
    public async Task Reconnect_DeployedDriver_TransitionsThroughReconnectingBackToHealthy()
    {
        var factory = new FakeReconnectDriverFactory();
        await using var harness = await TwoNodeClusterHarness.StartAsync(driverFactory: factory);

        var store = harness.NodeA.Services.GetRequiredService<IDriverStatusSnapshotStore>();

        // Capture every DriverHealthChanged the bridge pushes to the hub (the first SendCoreAsync arg).
        var captured = new List<DriverHealthChanged>();
        var captureLock = new object();
        var mockClients = new Mock<IHubClients>();
        var mockClientProxy = new Mock<IClientProxy>();
        mockClients.Setup(c => c.Group(It.IsAny<string>())).Returns(mockClientProxy.Object);
        mockClientProxy
            .Setup(p => p.SendCoreAsync(It.IsAny<string>(), It.IsAny<object?[]>(), It.IsAny<CancellationToken>()))
            .Callback<string, object?[], CancellationToken>((_, args, _) =>
            {
                if (args.FirstOrDefault() is DriverHealthChanged hc)
                    lock (captureLock) captured.Add(hc);
            })
            .Returns(Task.CompletedTask);
        var mockHub = new Mock<IHubContext<DriverStatusHub>>();
        mockHub.Setup(h => h.Clients).Returns(mockClients.Object);

        // Spawn the bridge + wait for its DPS SubscribeAck BEFORE deploying, so it catches the initial
        // Healthy publish (DPS is fire-and-forget with no replay, and repeat publishes are deduped).
        var bridge = harness.NodeASystem.ActorOf(
            DriverStatusSignalRBridge.Props(mockHub.Object, store),
            $"test-reconnect-bridge-{Guid.NewGuid():N}");
        await Task.Delay(TimeSpan.FromSeconds(2), Ct);

        try
        {
            // Validator-clean seed: a single cluster bound to NodeA with one enabled Modbus driver, no
            // equipment/tags (tags would trip DraftValidator → deploy Rejected).
            await SeedSingleDriverClusterAsync(harness);

            await using var scope = harness.NodeA.Services.CreateAsyncScope();
            var client = scope.ServiceProvider.GetRequiredService<IAdminOperationsClient>();

            var deploy = await client.StartDeploymentAsync(createdBy: "e2e", Ct);
            deploy.Outcome.ShouldBe(StartDeploymentOutcome.Accepted, $"Deploy not accepted: {deploy.Message}");

            // Wait until the driver is spawned (factory recorded it) AND reached Healthy in the store.
            await WaitForAsync(() => Task.FromResult(
                    factory.Created.TryGetValue(DriverId, out _)
                    && store.TryGet(DriverId, out var s) && s.State == "Healthy"),
                TimeSpan.FromSeconds(20));

            // Simulate the lost connection the operator Reconnect responds to.
            factory.Created[DriverId].ReportReconnecting();

            var result = await client.AskAsync<ReconnectDriverResult>(
                new ReconnectDriver(ClusterId, DriverId, "e2e", Guid.NewGuid()), Ct);
            result.Ok.ShouldBeTrue($"ReconnectDriver failed: {result.Message}");

            // The published health must walk Reconnecting → (later) Healthy for this driver.
            await WaitForAsync(() =>
            {
                lock (captureLock) return Task.FromResult(HasReconnectThenHealthy(captured));
            }, TimeSpan.FromSeconds(20));

            List<DriverHealthChanged> snapshot;
            lock (captureLock) snapshot = captured.Where(c => c.DriverInstanceId == DriverId).ToList();

            HasReconnectThenHealthy(snapshot).ShouldBeTrue(
                "Expected a Reconnecting push followed by a later Healthy push for the deployed driver. " +
                $"States seen: [{string.Join(", ", snapshot.Select(c => c.State))}]");

            store.TryGet(DriverId, out var final).ShouldBeTrue();
            final.State.ShouldBe("Healthy");

            // ≥ 2 proves the command genuinely re-initialised the driver via the full cluster path
            // (initial connect + at least one reconnect retry).
            factory.Created[DriverId].InitializeCount.ShouldBeGreaterThanOrEqualTo(2);
        }
        finally
        {
            harness.NodeASystem.Stop(bridge);
        }
    }

    /// <summary>
    ///     True when the captured pushes for <see cref="DriverId"/> contain a <c>Reconnecting</c> entry
    ///     followed by a strictly-later <c>Healthy</c> entry (the ordered sub-sequence the reconnect FSM
    ///     produces).
    /// </summary>
    private static bool HasReconnectThenHealthy(List<DriverHealthChanged> captured)
    {
        var states = captured.Where(c => c.DriverInstanceId == DriverId).Select(c => c.State).ToList();
        var reconnectAt = states.IndexOf("Reconnecting");
        if (reconnectAt < 0) return false;
        return states.Skip(reconnectAt + 1).Contains("Healthy");
    }

    /// <summary>
    ///     Seeds one single-node cluster bound to NodeA with one enabled Modbus <see cref="DriverInstance"/>
    ///     and no equipment/tags, so <c>StartDeploymentAsync</c> returns <c>Accepted</c> and NodeA's
    ///     <c>DriverHostActor</c> spawns the driver as a managed child. Mirrors
    ///     <c>MultiClusterScopingTests</c>'s validator-clean entity shapes.
    /// </summary>
    private static async Task SeedSingleDriverClusterAsync(TwoNodeClusterHarness harness)
    {
        await using var db = await harness.CreateConfigDbContextAsync();

        db.ServerClusters.Add(new ServerCluster
        {
            ClusterId = ClusterId,
            Name = "Reconnect E2E Cluster",
            Enterprise = "zb",
            Site = "central",
            NodeCount = 1,
            RedundancyMode = RedundancyMode.None,
            CreatedBy = "test",
        });

        db.Namespaces.Add(new Namespace
        {
            NamespaceId = "RECONNECT-E2E-equipment",
            ClusterId = ClusterId,
            Kind = NamespaceKind.Equipment,
            NamespaceUri = "urn:zb:reconnect-e2e:equipment",
        });

        db.ClusterNodes.Add(new ClusterNode
        {
            NodeId = harness.NodeANodeId,
            ClusterId = ClusterId,
            Host = TwoNodeClusterHarness.LoopbackHost,
            ApplicationUri = "urn:zb:reconnect-e2e:node-a",
            CreatedBy = "test",
        });

        db.DriverInstances.Add(new DriverInstance
        {
            DriverInstanceId = DriverId,
            ClusterId = ClusterId,
            NamespaceId = "RECONNECT-E2E-equipment",
            Name = DriverId,
            DriverType = "Modbus",
            Enabled = true,
            DriverConfig = "{}",
        });

        await db.SaveChangesAsync(Ct);
    }

    /// <summary>Polls <paramref name="condition"/> every 100 ms until it returns true or
    /// <paramref name="timeout"/> elapses (then throws <see cref="TimeoutException"/>).</summary>
    private static async Task WaitForAsync(Func<Task<bool>> condition, TimeSpan timeout)
    {
        var deadline = DateTime.UtcNow + timeout;
        while (DateTime.UtcNow < deadline)
        {
            if (await condition()) return;
            await Task.Delay(100);
        }
        throw new TimeoutException($"Condition not met within {timeout}");
    }
}