using Opc.Ua;
using Opc.Ua.Client;
using Shouldly;
using Xunit;
using ZB.MOM.WW.OtOpcUa.Commons.OpcUa;
using ZB.MOM.WW.OtOpcUa.Configuration.Enums;
using ZB.MOM.WW.OtOpcUa.Core.Abstractions;
using static ZB.MOM.WW.OtOpcUa.OpcUaServer.IntegrationTests.ServerEventRig;

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

/// <summary>
///     Gitea #588 over the wire — with <c>Security:Acl:Enabled</c> on, the server-wide events this node manager
///     raises (<c>GeneralModelChangeEvent</c>s, <c>AuditWriteUpdateEvent</c>s) reach a Server-object
///     (<c>i=2253</c>) item only when its session may see the node the event names.
/// </summary>
/// <remarks>
///     <para>
///         They used to go straight to <c>Server.ReportEvent</c> and the core node manager's Server object, which
///         queues to every all-events item with no ACL decision — so a session with no grant learned, from a
///         model-change event, the RawPath of every node added, deleted or retyped under it.
///     </para>
///     <para>
///         The withheld session is granted <see cref="ServerEventRig.EqA"/> only, so the absence of the raw
///         event on its item is paired with a positive control <b>on the same item</b>: the sentinel event about
///         <see cref="ServerEventRig.EqA"/> is reported after the withheld one, through the same path, and must
///         arrive.
///     </para>
/// </remarks>
public sealed class AclServerObjectModelChangeTests
{
    private const string RawVariable = "Plant/Modbus/dev1/Speed";

    private const NodePermissions See = NodePermissions.Browse | NodePermissions.Read | NodePermissions.Subscribe;

    /// <summary>
    ///     A NodeAdded / NodeDeleted / DataTypeChanged model-change event naming a raw node reaches the
    ///     cluster-granted session and not the session granted only an equipment folder — which still receives
    ///     the one naming its own folder.
    /// </summary>
    [Theory]
    [InlineData("NodeAdded")]
    [InlineData("NodeDeleted")]
    [InlineData("DataTypeChanged")]
    public async Task A_model_change_naming_a_node_the_session_cannot_browse_is_withheld(string verb)
    {
        var ct = TestContext.Current.CancellationToken;
        var rig = await StartAsync($"AclModelChange{verb}", encrypted: false, ct);
        try
        {
            rig.Enforce(true, [Key()], ClusterGrant(KeyPrincipal, "acl-key", See), EquipmentGrant(EqA, See));
            rig.EnsureEquipment();
            rig.Sink.EnsureFolder(RawDeviceFolder, parentNodeId: null, displayName: "dev1", realm: AddressSpaceRealm.Raw);
            rig.Sink.EnsureVariable(RawVariable, RawDeviceFolder, "Speed", "Int32", writable: false, AddressSpaceRealm.Raw);

            var (granted, grantedEvents, grantedItem, grantedSubscription) = await ServerObjectAsync(rig, anonymous: false, ct);
            var (narrow, narrowEvents, narrowItem, narrowSubscription) = await ServerObjectAsync(rig, anonymous: true, ct);

            switch (verb)
            {
                case "NodeAdded": rig.Sink.RaiseNodesAddedModelChange(RawDeviceFolder, AddressSpaceRealm.Raw); break;
                case "NodeDeleted": rig.Sink.RemoveVariableNode(RawVariable, AddressSpaceRealm.Raw).ShouldBeTrue(); break;
                default:
                    rig.Sink.UpdateTagAttributes(RawVariable, false, null, "Double", false, null, AddressSpaceRealm.Raw).ShouldBeTrue();
                    break;
            }

            rig.Sink.RaiseNodesAddedModelChange(EqA, AddressSpaceRealm.Uns);

            await RecordedEvents.WaitUntilAsync(() =>
                grantedEvents.Of(grantedItem).Count(e => NamesEqA(e)) == 1
                && narrowEvents.Of(narrowItem).Any(NamesEqA));

            var rawNames = verb == "NodeAdded" ? RawDeviceFolder : RawVariable;
            grantedEvents.Of(grantedItem).Count(e => Names(e, rawNames)).ShouldBe(1, "the granted control receives the raw change");
            narrowEvents.Of(narrowItem).Where(e => Names(e, rawNames)).ShouldBeEmpty(
                "a session that cannot browse the node must not learn its name from a model-change event");
            narrowEvents.Of(narrowItem).Count.ShouldBe(1, "only the change to its own equipment folder");

            await narrowSubscription.DeleteAsync(true, ct);
            await grantedSubscription.DeleteAsync(true, ct);
            narrow.Dispose();
            granted.Dispose();
        }
        finally { await rig.DisposeAsync(); }
    }

    /// <summary>
    ///     With enforcement off nothing changes: a session holding no grant at all still receives the raw
    ///     model-change event through the Server object, exactly once.
    /// </summary>
    /// <remarks>Without this the test above also passes on a build that withholds every model change from everyone.</remarks>
    [Fact]
    public async Task With_acl_enforcement_off_every_server_object_item_receives_the_model_change()
    {
        var ct = TestContext.Current.CancellationToken;
        var rig = await StartAsync("AclModelChangeOff", encrypted: false, ct);
        try
        {
            rig.Enforce(false, [Key()], ClusterGrant(KeyPrincipal, "acl-key", See));
            rig.Sink.EnsureFolder(RawDeviceFolder, parentNodeId: null, displayName: "dev1", realm: AddressSpaceRealm.Raw);

            var (session, events, item, subscription) = await ServerObjectAsync(rig, anonymous: true, ct);

            rig.Sink.RaiseNodesAddedModelChange(RawDeviceFolder, AddressSpaceRealm.Raw);
            await RecordedEvents.WaitUntilAsync(() => events.Of(item).Any(e => Names(e, RawDeviceFolder)));
            await Task.Delay(TimeSpan.FromMilliseconds(300), ct);
            events.Of(item).Count(e => Names(e, RawDeviceFolder)).ShouldBe(1);

            await subscription.DeleteAsync(true, ct);
            session.Dispose();
        }
        finally { await rig.DisposeAsync(); }
    }

    /// <summary>
    ///     With auditing on over an encrypted channel, a rejected device write's <c>AuditWriteUpdateEvent</c> —
    ///     which carries the written value and the node's prior one — reaches a session granted <c>Read</c> on
    ///     the node and not one granted only an equipment folder.
    /// </summary>
    /// <remarks>
    ///     Auditing is off by default (<c>ServerConfiguration.AuditingEnabled</c>, which this repo never sets),
    ///     and audit events only ever leave over SignAndEncrypt — so both sessions are encrypted here, or the
    ///     withheld one would be denied by the channel rather than by the ACL and the test would prove nothing.
    /// </remarks>
    [Fact]
    public async Task An_audit_write_event_reaches_only_sessions_that_may_read_the_node()
    {
        var ct = TestContext.Current.CancellationToken;
        var rig = await StartAsync("AclAuditWrite", encrypted: true, ct);
        try
        {
            rig.Enforce(
                true, [Key()],
                ClusterGrant(KeyPrincipal, "acl-key", See | NodePermissions.WriteOperate), EquipmentGrant(EqA, See));
            rig.SetAuditing(true);
            rig.EnsureEquipment();
            rig.Sink.EnsureFolder(RawDeviceFolder, parentNodeId: null, displayName: "dev1", realm: AddressSpaceRealm.Raw);
            rig.Sink.EnsureVariable(RawVariable, RawDeviceFolder, "Speed", "Int32", writable: true, AddressSpaceRealm.Raw);
            rig.Nm.NodeWriteGateway = new RejectingGateway();

            var (granted, grantedEvents, grantedItem, grantedSubscription) =
                await ServerObjectAsync(rig, anonymous: false, ct, encrypted: true);
            var (narrow, narrowEvents, narrowItem, narrowSubscription) =
                await ServerObjectAsync(rig, anonymous: true, ct, encrypted: true);

            var variable = new NodeId(RawVariable, (ushort)granted.NamespaceUris.GetIndex(V3NodeIds.RawNamespaceUri));
            var write = await granted.WriteAsync(
                null,
                [new WriteValue { NodeId = variable, AttributeId = Attributes.Value, Value = new DataValue(new Variant(42)) }],
                ct);
            StatusCode.IsGood(write.Results[0]).ShouldBeTrue();

            await RecordedEvents.WaitUntilAsync(() =>
                grantedEvents.HasType(grantedItem, ObjectTypeIds.AuditWriteUpdateEventType));

            // Reported after the audit event through the same delivery, so it queues behind it on the item.
            rig.Sink.RaiseNodesAddedModelChange(EqA, AddressSpaceRealm.Uns);
            await RecordedEvents.WaitUntilAsync(() => narrowEvents.Of(narrowItem).Any(NamesEqA));

            narrowEvents.HasType(narrowItem, ObjectTypeIds.AuditWriteUpdateEventType).ShouldBeFalse(
                "a session that may not read the node must not receive its written values through an audit event");

            await narrowSubscription.DeleteAsync(true, ct);
            await grantedSubscription.DeleteAsync(true, ct);
            narrow.Dispose();
            granted.Dispose();
        }
        finally { await rig.DisposeAsync(); }
    }

    // ───────────────────────────── helpers ─────────────────────────────

    private static async Task<(ISession Session, RecordedEvents Events, MonitoredItem Item, Subscription Subscription)>
        ServerObjectAsync(ServerEventRig rig, bool anonymous, CancellationToken ct, bool encrypted = false)
    {
        var session = await rig.ConnectAsync(anonymous, ct, encrypted);
        var events = new RecordedEvents();
        var subscription = await RecordedEvents.SubscribeAsync(session, events, ct);
        var item = RecordedEvents.AddEventItem(subscription, ObjectIds.Server);
        await subscription.ApplyChangesAsync(ct);
        item.Status.Error.ShouldBeNull();
        return (session, events, item, subscription);
    }

    private static bool NamesEqA(VariantCollection e) => Names(e, EqA);

    /// <summary>Whether a model-change event's <c>Changes</c> name the node whose identifier is <paramref name="id"/>.</summary>
    private static bool Names(VariantCollection e, string id) =>
        e[RecordedEvents.ChangesField].Value is ExtensionObject[] changes
        && changes.Any(c => c.Body is ModelChangeStructureDataType { Affected: { } affected }
                            && affected.Identifier as string == id);

    /// <summary>Every device write fails, so the node manager reverts and audits it.</summary>
    private sealed class RejectingGateway : IOpcUaNodeWriteGateway
    {
        /// <inheritdoc />
        public Task<NodeWriteOutcome> WriteAsync(string nodeId, object? value, AddressSpaceRealm realm, CancellationToken ct) =>
            Task.FromResult(new NodeWriteOutcome(false, "rejected by the test device"));
    }
}