using Akka.Actor;
using Shouldly;
using Xunit;
using ZB.MOM.WW.OtOpcUa.Commons.Messages.Redundancy;
using ZB.MOM.WW.OtOpcUa.Commons.Types;
using ZB.MOM.WW.OtOpcUa.Runtime.Drivers;
using ZB.MOM.WW.OtOpcUa.Runtime.Redundancy;
using ZB.MOM.WW.OtOpcUa.Runtime.Tests.Harness;

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

/// <summary>
///     Gitea #537 — the bridge that carries the continuous-historization <b>capture</b> verdict out of
///     the actor and into <see cref="IHistorizationRoleView"/>, where the recorder reads it per value.
/// </summary>
/// <remarks>
///     <para>
///         Both nodes of a redundant pair serve the same address space and see the same dependency-mux
///         fan-out, so an ungated recorder writes every sample twice. Measured on the docker-dev central
///         pair against a real gateway: the write counter advanced twice per value, and halved when one
///         node was stopped.
///     </para>
///     <para>
///         These cases share the role rule with <see cref="DriverHostActorRoleViewTests"/> but differ on
///         which peer counts. The alarm queue replicates, so the relevant peer is whoever holds a copy
///         of this node's rows; historization is fleet-wide by historian tag name, so the relevant peer
///         is whoever records this node's refs — a partner in its own per-cluster mesh.
///     </para>
/// </remarks>
public sealed class DriverHostActorHistorizationRoleViewTests : RuntimeActorTestBase
{
    private static readonly NodeId TestNode = NodeId.Parse("driver-histview-test");
    private static readonly NodeId MeshPeer = NodeId.Parse("mesh-peer:4053");
    private static readonly NodeId ForeignNode = NodeId.Parse("other-cluster:4053");
    private static readonly TimeSpan Timeout = PresenceBudget;

    /// <summary>
    ///     Before any snapshot arrives the view must read open, not closed.
    /// </summary>
    /// <remarks>
    ///     A deployment that runs no redundancy never publishes here at all. Defaulting closed would
    ///     leave it with no trend data whatsoever and nothing to say why.
    /// </remarks>
    [Fact]
    public void An_unpublished_view_captures()
        => new RedundancyRoleView().ShouldRecordHistorizedValues.ShouldBeTrue();

    /// <summary>A Secondary stands down for a Primary in its own mesh — the duplicate-write case.</summary>
    [Fact]
    public void Secondary_stands_down_for_a_primary_in_its_own_mesh()
    {
        var view = new RecordingHistorizationView();
        SpawnHost(view, sharesScopeWith: MeshPeer).Tell(Snapshot(
            (TestNode, RedundancyRole.Secondary), (MeshPeer, RedundancyRole.Primary)));

        AwaitAssert(() => view.Published.ShouldBe([false]), duration: Timeout);
    }

    /// <summary>
    ///     A Secondary whose Primary is in ANOTHER cluster keeps capturing.
    /// </summary>
    /// <remarks>
    ///     That node runs a different configuration and records none of these tags, so standing down for
    ///     it would end this cluster's historization silently — the drain would simply report success on
    ///     an empty outbox forever. Same scope mismatch that once suspended the alarm drain fleet-wide.
    /// </remarks>
    [Fact]
    public void Secondary_keeps_capturing_when_the_primary_records_other_tags()
    {
        var view = new RecordingHistorizationView();
        SpawnHost(view, sharesScopeWith: MeshPeer).Tell(Snapshot(
            (TestNode, RedundancyRole.Secondary), (ForeignNode, RedundancyRole.Primary)));

        AwaitAssert(() => view.Published.ShouldBe([true]), duration: Timeout);
    }

    /// <summary>
    ///     With NO way to establish which peers share this node's address space, it never stands down.
    /// </summary>
    /// <remarks>
    ///     The predicate is null on a node carrying no cluster-scoped role — the legacy, pre-Phase-6
    ///     shape, where the redundancy election is fleet-wide and the elected Primary usually belongs to
    ///     some other cluster. Duplicates are recoverable; a silent gap is not, so unproven means
    ///     capture. Delete the null check in the wiring and this is the case that goes red.
    /// </remarks>
    [Fact]
    public void An_unprovable_scope_never_stands_down()
    {
        var view = new RecordingHistorizationView();
        SpawnHost(view, sharesScopeWith: null).Tell(Snapshot(
            (TestNode, RedundancyRole.Secondary), (MeshPeer, RedundancyRole.Primary)));

        AwaitAssert(() => view.Published.ShouldBe([true]), duration: Timeout);
    }

    /// <summary>Primary captures.</summary>
    [Fact]
    public void Primary_captures()
    {
        var view = new RecordingHistorizationView();
        SpawnHost(view, sharesScopeWith: MeshPeer).Tell(Snapshot(
            (TestNode, RedundancyRole.Primary), (MeshPeer, RedundancyRole.Secondary)));

        // Published, not current — `true` is also the seed, so asserting the property would pass before
        // the actor had processed anything.
        AwaitAssert(() => view.Published.ShouldBe([true]), duration: Timeout);
    }

    /// <summary>
    ///     Unknown role captures — the snapshot never names this node, the documented identity-mismatch
    ///     shape.
    /// </summary>
    [Fact]
    public void Unknown_role_captures()
    {
        var view = new RecordingHistorizationView();
        SpawnHost(view, sharesScopeWith: MeshPeer).Tell(Snapshot(
            (MeshPeer, RedundancyRole.Primary), (ForeignNode, RedundancyRole.Secondary)));

        AwaitAssert(() => view.Published.ShouldBe([true]), duration: Timeout);
    }

    /// <summary>A promotion must MOVE the view, not merely leave it at its open seed.</summary>
    [Fact]
    public void A_promotion_reopens_a_closed_view()
    {
        var view = new RecordingHistorizationView();
        IActorRef host = SpawnHost(view, sharesScopeWith: MeshPeer);

        host.Tell(Snapshot((TestNode, RedundancyRole.Secondary), (MeshPeer, RedundancyRole.Primary)));
        AwaitAssert(() => view.Published.ShouldBe([false]), duration: Timeout);

        host.Tell(Snapshot((TestNode, RedundancyRole.Primary), (MeshPeer, RedundancyRole.Secondary)));
        AwaitAssert(() => view.Published.ShouldBe([false, true]), duration: Timeout);
    }

    // ---------------- helpers ----------------

    /// <summary>
    ///     A view that remembers every published decision, so a test asserts on the actor's ACTION
    ///     rather than on a state its open seed already satisfies.
    /// </summary>
    private sealed class RecordingHistorizationView : IHistorizationRoleView
    {
        private readonly List<bool> _published = [];
        private readonly Lock _gate = new();
        private readonly RedundancyRoleView _inner = new();

        /// <summary>Every value published so far, in order.</summary>
        public IReadOnlyList<bool> Published
        {
            get { lock (_gate) return _published.ToArray(); }
        }

        public bool ShouldRecordHistorizedValues => _inner.ShouldRecordHistorizedValues;

        public void PublishHistorizationRole(bool shouldRecordHistorizedValues)
        {
            lock (_gate) _published.Add(shouldRecordHistorizedValues);
            _inner.PublishHistorizationRole(shouldRecordHistorizedValues);
        }
    }

    private IActorRef SpawnHost(IHistorizationRoleView view, NodeId? sharesScopeWith) =>
        Sys.ActorOf(DriverHostActor.Props(
            NewInMemoryDbFactory(),
            TestNode,
            ackRouter: null,
            driverMemberCountProvider: () => 2,
            historizationRoleView: view,
            sharesHistorizationScopeWithLocal:
                sharesScopeWith is { } peer ? node => node == peer : null));

    private static RedundancyStateChanged Snapshot(params (NodeId Node, RedundancyRole Role)[] nodes) =>
        new(
            nodes.Select(n => new NodeRedundancyState(
                    n.Node,
                    n.Role,
                    IsClusterLeader: n.Role == RedundancyRole.Primary,
                    IsDriverPrimary: n.Role == RedundancyRole.Primary,
                    AsOfUtc: DateTime.UtcNow))
                .ToList(),
            CorrelationId.NewId());
}