using Microsoft.Extensions.Logging.Abstractions;
using Opc.Ua;
using Opc.Ua.Server;
using Shouldly;
using Xunit;
using ZB.MOM.WW.OtOpcUa.Commons.OpcUa;
using ZB.MOM.WW.OtOpcUa.Configuration.Entities;
using ZB.MOM.WW.OtOpcUa.Configuration.Enums;
using ZB.MOM.WW.OtOpcUa.Core.Abstractions;
using ZB.MOM.WW.OtOpcUa.Core.Authorization;
using ZB.MOM.WW.OtOpcUa.OpcUaServer.Security;
using SdkHistoryReadResult = Opc.Ua.HistoryReadResult;

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

/// <summary>
///     #520 stage 5 — enforcement at the node manager's own seams, through a REAL booted
///     <see cref="OtOpcUaSdkServer"/> and the SDK's own dispatch. <see cref="DataPlaneAuthorizerTests"/>
///     proves the decision; this proves the decision is actually consulted, which is the half that has
///     historically gone wrong in this repo (a correct component wired to nothing, or wired behind a
///     branch that never runs).
/// </summary>
/// <remarks>
///     HistoryRead is the seam exercised end-to-end because it is reachable through the node manager's
///     public entry point with no client socket, and because it had <b>no authorization check of any kind</b>
///     before this stage — so a green result here is the difference between "any session can read all
///     history" and "a grant is required".
/// </remarks>
public sealed class NodeManagerAclEnforcementTests : IDisposable
{
    private const string Cluster = "SITE-A";
    private const string Principal = "scadabridge";

    private static CancellationToken Ct => TestContext.Current.CancellationToken;

    private readonly string _pkiRoot = Path.Combine(
        Path.GetTempPath(), $"otopcua-acl-{Guid.NewGuid():N}");

    /// <summary>
    ///     With enforcement OFF, HistoryRead behaves exactly as it always has — no identity is required and
    ///     nothing is denied. This is the flag's whole promise, and it is the assertion that would catch a
    ///     change accidentally enforcing by default.
    /// </summary>
    [Fact]
    public async Task History_read_is_ungated_while_enforcement_is_off()
    {
        var (host, server) = await BootAsync();
        try
        {
            var nm = server.NodeManager!;
            nm.HistorianDataSource = NullHistorianDataSource.Instance;
            nm.Authorizer = Authorizer(enabled: false, GrantOn(NodePermissions.HistoryRead));
            var nodeId = Historized(nm, "Plant/Modbus/dev1/Speed");

            var (_, errors) = ReadRaw(nm, identity: null, nodeId);

            errors[0].StatusCode.Code.ShouldNotBe(StatusCodes.BadUserAccessDenied);
        }
        finally { await host.DisposeAsync(); }
    }

    /// <summary>
    ///     With enforcement ON, an AUTHENTICATED session whose principal holds a grant that does not carry
    ///     the HistoryRead bit is refused — the check the seam never had.
    /// </summary>
    /// <remarks>
    ///     The identity is deliberately real and the grant deliberately non-empty. Denying an anonymous
    ///     context would pass against a gate that only ever checks for a null identity and never consults a
    ///     grant at all, which is most of what could go wrong here.
    /// </remarks>
    [Fact]
    public async Task History_read_is_denied_without_the_permission_once_enforcement_is_on()
    {
        var (host, server) = await BootAsync();
        try
        {
            var nm = server.NodeManager!;
            nm.HistorianDataSource = NullHistorianDataSource.Instance;
            nm.Authorizer = Authorizer(enabled: true, GrantOn(NodePermissions.Read));
            var nodeId = Historized(nm, "Plant/Modbus/dev1/Speed");

            var (results, errors) = ReadRaw(nm, Identity(), nodeId);

            errors[0].StatusCode.Code.ShouldBe(StatusCodes.BadUserAccessDenied);
            // Not BadHistoryOperationUnsupported: "you may not read this" and "this node has no history"
            // are different facts, and reporting the wrong one sends an operator debugging historisation.
            results[0].StatusCode.Code.ShouldBe(StatusCodes.BadUserAccessDenied);
        }
        finally { await host.DisposeAsync(); }
    }

    /// <summary>
    ///     #668: a modified-value read (<c>IsReadModified = true</c>) is gated by the SAME HistoryRead decision — no new
    ///     operation. Denied without the bit; the granted principal reaches the backend (Null ⇒ unsupported, which is
    ///     "allowed but no trail", a different fact from the denial).
    /// </summary>
    [Fact]
    public async Task Modified_history_read_is_gated_by_the_history_read_grant()
    {
        var (host, server) = await BootAsync();
        try
        {
            var nm = server.NodeManager!;
            nm.HistorianDataSource = new OneModificationTrail();
            var nodeId = Historized(nm, "Plant/Modbus/dev1/Speed");

            nm.Authorizer = Authorizer(enabled: true, GrantOn(NodePermissions.Read));
            var (deniedResults, deniedErrors) = ReadRaw(nm, Identity(), modified: true, nodeId);
            deniedErrors[0].StatusCode.Code.ShouldBe(StatusCodes.BadUserAccessDenied);
            deniedResults[0].StatusCode.Code.ShouldBe(StatusCodes.BadUserAccessDenied);

            nm.Authorizer = Authorizer(enabled: true, GrantOn(NodePermissions.HistoryRead));
            var (allowedResults, allowedErrors) = ReadRaw(nm, Identity(), modified: true, nodeId);
            // A real trail entry must come back: Null's BadHistoryOperationUnsupported is also what the SDK pre-seeds,
            // so asserting it would pass even if the grant never reached the modified branch.
            allowedErrors[0].StatusCode.Code.ShouldBe(StatusCodes.Good);
            allowedResults[0].StatusCode.Code.ShouldBe(StatusCodes.Good);
            var data = ExtensionObject.ToEncodeable(allowedResults[0].HistoryData).ShouldBeOfType<HistoryModifiedData>();
            data.DataValues.Count.ShouldBe(1);
            data.ModificationInfos[0].UserName.ShouldBe("alice");
        }
        finally { await host.DisposeAsync(); }
    }

    /// <summary>A granted principal reads normally — the gate is not simply denying everything.</summary>
    [Fact]
    public async Task History_read_succeeds_for_a_granted_principal()
    {
        var (host, server) = await BootAsync();
        try
        {
            var nm = server.NodeManager!;
            nm.HistorianDataSource = NullHistorianDataSource.Instance;
            nm.Authorizer = Authorizer(enabled: true, GrantOn(NodePermissions.HistoryRead));
            var nodeId = Historized(nm, "Plant/Modbus/dev1/Speed");

            var (_, errors) = ReadRaw(nm, Identity(), nodeId);

            errors[0].StatusCode.Code.ShouldNotBe(StatusCodes.BadUserAccessDenied);
        }
        finally { await host.DisposeAsync(); }
    }

    /// <summary>
    ///     A mixed batch is decided per node: the granted node answers and the ungranted one is denied, in
    ///     the same request. Failing the whole batch would be easier and would also withhold data the client
    ///     was entitled to.
    /// </summary>
    [Fact]
    public async Task A_mixed_batch_denies_only_the_ungranted_node()
    {
        var (host, server) = await BootAsync();
        try
        {
            var nm = server.NodeManager!;
            nm.HistorianDataSource = NullHistorianDataSource.Instance;

            var grant = new NodeAcl
            {
                NodeAclId = "acl-dev1",
                ClusterId = Cluster,
                Principal = Principal,
                ScopeKind = NodeAclScopeKind.RawDevice,
                ScopeId = "dev-1",
                PermissionFlags = NodePermissions.HistoryRead,
            };
            nm.Authorizer = Authorizer(
                enabled: true, grant,
                new Dictionary<AclScopeRef, IReadOnlyList<NodeAclPath>>
                {
                    [new AclScopeRef(NodeAclScopeKind.RawDevice, "dev-1")] =
                        [new NodeAclPath(["raw", "Plant", "Modbus", "dev1"])],
                });

            var allowed = Historized(nm, "Plant/Modbus/dev1/Speed");
            var denied = Historized(nm, "Plant/Modbus/dev2/Speed");

            var (_, errors) = ReadRaw(nm, Identity(), allowed, denied);

            errors[0].StatusCode.Code.ShouldNotBe(StatusCodes.BadUserAccessDenied);
            errors[1].StatusCode.Code.ShouldBe(StatusCodes.BadUserAccessDenied);
        }
        finally { await host.DisposeAsync(); }
    }

    // ───────────────────────────── the alarm seam's operation mapping ─────────────────────────────

    /// <summary>
    ///     Every Part 9 method name the node manager routes maps onto the permission it should require.
    ///     The <c>AlarmAck</c> role this replaces could not distinguish these at all — one role covered
    ///     acknowledge, confirm and shelve — so the mapping is new authority granularity, not a rename.
    /// </summary>
    /// <remarks>
    ///     The inputs are the exact literals the <c>OnAcknowledge</c> / <c>OnShelve</c> / <c>OnEnableDisable</c>
    ///     delegates pass, not invented ones; a mapping that agreed with itself but not with its callers
    ///     would grant the wrong permission and this test would not notice.
    /// </remarks>
    [Theory]
    [InlineData("Acknowledge", OpcUaOperation.AlarmAcknowledge)]
    [InlineData("Confirm", OpcUaOperation.AlarmConfirm)]
    [InlineData("OneShotShelve", OpcUaOperation.AlarmShelve)]
    [InlineData("TimedShelve", OpcUaOperation.AlarmShelve)]
    [InlineData("Unshelve", OpcUaOperation.AlarmShelve)]
    // AddComment / Enable / Disable have no OpcUaOperation of their own, so they take the most
    // restrictive available reading — acknowledge is the permission "may act on alarms at all" grants.
    [InlineData("AddComment", OpcUaOperation.AlarmAcknowledge)]
    [InlineData("Enable", OpcUaOperation.AlarmAcknowledge)]
    [InlineData("Disable", OpcUaOperation.AlarmAcknowledge)]
    public void Part9_method_names_map_to_their_permission(string method, OpcUaOperation expected) =>
        OtOpcUaNodeManager.AlarmOperationFor(method).ShouldBe(expected);

    // ───────────────────────────── the write seam ─────────────────────────────

    /// <summary>
    ///     With enforcement ON, the ACL decision REPLACES the <c>WriteOperate</c> role check — an identity
    ///     carrying NO roles at all writes successfully on the strength of its grant alone.
    /// </summary>
    /// <remarks>
    ///     This is the assertion that proves the two gates are alternatives rather than a chain. Run them in
    ///     series and this write is refused, because only a Cluster-scoped grant confers the server-wide
    ///     role — which is exactly the "narrow grants stay inert" outcome the stage exists to end. A test
    ///     that only checked denials would be satisfied by a build that denies everything.
    /// </remarks>
    [Fact]
    public async Task An_acl_grant_authorizes_a_write_from_a_session_carrying_no_roles()
    {
        var (host, server) = await BootAsync();
        try
        {
            var nm = server.NodeManager!;
            var gateway = new RecordingWriteGateway();
            nm.NodeWriteGateway = gateway;
            nm.Authorizer = Authorizer(enabled: true, GrantOn(NodePermissions.WriteOperate));
            var nodeId = Writable(nm, "Plant/Modbus/dev1/Setpoint");

            var errors = Write(nm, Identity(), nodeId, 42f);

            errors[0].StatusCode.Code.ShouldBe(StatusCodes.Good);
            gateway.Writes.ShouldHaveSingleItem();
        }
        finally { await host.DisposeAsync(); }
    }

    /// <summary>
    ///     And the converse: a principal whose grant lacks <c>WriteOperate</c> is refused, and — the part
    ///     that matters beyond the status code — <b>nothing is dispatched to the device</b>. A gate that
    ///     denied the client but still routed the write would be worse than no gate at all.
    /// </summary>
    [Fact]
    public async Task A_denied_write_never_reaches_the_device()
    {
        var (host, server) = await BootAsync();
        try
        {
            var nm = server.NodeManager!;
            var gateway = new RecordingWriteGateway();
            nm.NodeWriteGateway = gateway;
            nm.Authorizer = Authorizer(enabled: true, GrantOn(NodePermissions.Read));
            var nodeId = Writable(nm, "Plant/Modbus/dev1/Setpoint");

            var errors = Write(nm, Identity(), nodeId, 42f);

            errors[0].StatusCode.Code.ShouldBe(StatusCodes.BadUserAccessDenied);
            gateway.Writes.ShouldBeEmpty();
        }
        finally { await host.DisposeAsync(); }
    }

    /// <summary>
    ///     With enforcement OFF the role gate still stands: a session with no roles is refused exactly as
    ///     before this stage. Pins that the flag's off-path is untouched, in the direction that matters.
    /// </summary>
    [Fact]
    public async Task A_roleless_write_is_still_denied_while_enforcement_is_off()
    {
        var (host, server) = await BootAsync();
        try
        {
            var nm = server.NodeManager!;
            var gateway = new RecordingWriteGateway();
            nm.NodeWriteGateway = gateway;
            nm.Authorizer = Authorizer(enabled: false, GrantOn(NodePermissions.WriteOperate));
            var nodeId = Writable(nm, "Plant/Modbus/dev1/Setpoint");

            var errors = Write(nm, Identity(), nodeId, 42f);

            errors[0].StatusCode.Code.ShouldBe(StatusCodes.BadUserAccessDenied);
            gateway.Writes.ShouldBeEmpty();
        }
        finally { await host.DisposeAsync(); }
    }

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

    private static NodeId Writable(OtOpcUaNodeManager nm, string rawPath)
    {
        nm.EnsureVariable(rawPath, parentFolderNodeId: null, displayName: rawPath, dataType: "Float",
            writable: true, historianTagname: null, realm: AddressSpaceRealm.Raw);
        return nm.TryGetVariable(rawPath, AddressSpaceRealm.Raw)!.NodeId;
    }

    private static List<ServiceResult> Write(
        OtOpcUaNodeManager nm, IUserIdentity? identity, NodeId nodeId, object value)
    {
        var context = new OperationContext(
            new RequestHeader(), secureChannelContext: null, RequestType.Write, identity);

        var writes = new List<WriteValue>
        {
            new()
            {
                NodeId = nodeId,
                AttributeId = Attributes.Value,
                Value = new DataValue(new Variant(value)) { StatusCode = StatusCodes.Good },
            },
        };
        var errors = Enumerable.Repeat<ServiceResult>(null!, writes.Count).ToList();

        nm.Write(context, writes, errors);
        return errors;
    }

    /// <summary>Records what actually reached the device, so a denial can be shown to route nothing.</summary>
    private sealed class RecordingWriteGateway : IOpcUaNodeWriteGateway
    {
        public List<string> Writes { get; } = [];

        public Task<NodeWriteOutcome> WriteAsync(
            string nodeId, object? value, AddressSpaceRealm realm, CancellationToken ct)
        {
            lock (Writes) Writes.Add(nodeId);
            return Task.FromResult(new NodeWriteOutcome(true, null));
        }
    }

    /// <summary>A backend whose modified-value trail holds exactly one entry; every other read is empty.</summary>
    private sealed class OneModificationTrail : IHistorianDataSource
    {
        public Task<HistoryModifiedReadResult> ReadModifiedAsync(
            string fullReference, DateTime startUtc, DateTime endUtc, uint maxValues, HistoryModifiedCursor? resumeAfter,
            CancellationToken cancellationToken)
        {
            var t = DateTime.UtcNow.AddMinutes(-5);
            var prior = new DataValueSnapshot(1.5, StatusCodes.Good, t, t);
            return Task.FromResult(new HistoryModifiedReadResult(
                [new HistoryModifiedValue(prior, DateTime.UtcNow, HistoryModificationType.Replace, "alice", 1, t)], false));
        }

        public Task<ZB.MOM.WW.OtOpcUa.Core.Abstractions.HistoryReadResult> ReadRawAsync(string r, DateTime s, DateTime e, uint m, CancellationToken ct) =>
            NullHistorianDataSource.Instance.ReadRawAsync(r, s, e, m, ct);
        public Task<ZB.MOM.WW.OtOpcUa.Core.Abstractions.HistoryReadResult> ReadProcessedAsync(
            string r, DateTime s, DateTime e, TimeSpan i, HistoryAggregateType a, CancellationToken ct) =>
            NullHistorianDataSource.Instance.ReadProcessedAsync(r, s, e, i, a, ct);
        public Task<ZB.MOM.WW.OtOpcUa.Core.Abstractions.HistoryReadResult> ReadAtTimeAsync(string r, IReadOnlyList<DateTime> t, CancellationToken ct) =>
            NullHistorianDataSource.Instance.ReadAtTimeAsync(r, t, ct);
        public Task<HistoricalEventsResult> ReadEventsAsync(string? n, DateTime s, DateTime e, int m, CancellationToken ct) =>
            NullHistorianDataSource.Instance.ReadEventsAsync(n, s, e, m, ct);
        public HistorianHealthSnapshot GetHealthSnapshot() => NullHistorianDataSource.Instance.GetHealthSnapshot();
        public void Dispose() { }
    }

    private static NodeId Historized(OtOpcUaNodeManager nm, string rawPath)
    {
        nm.EnsureVariable(rawPath, parentFolderNodeId: null, displayName: rawPath, dataType: "Float",
            writable: false, historianTagname: rawPath, realm: AddressSpaceRealm.Raw);
        return nm.TryGetVariable(rawPath, AddressSpaceRealm.Raw)!.NodeId;
    }

    private static (List<SdkHistoryReadResult> Results, List<ServiceResult> Errors) ReadRaw(
        OtOpcUaNodeManager nm, IUserIdentity? identity, params NodeId[] nodeIds) =>
        ReadRaw(nm, identity, modified: false, nodeIds);

    private static (List<SdkHistoryReadResult> Results, List<ServiceResult> Errors) ReadRaw(
        OtOpcUaNodeManager nm, IUserIdentity? identity, bool modified, params NodeId[] nodeIds)
    {
        var context = new OperationContext(
            new RequestHeader(), secureChannelContext: null, RequestType.HistoryRead, identity);

        var nodesToRead = nodeIds.Select(id => new HistoryReadValueId { NodeId = id }).ToList();
        var results = Enumerable.Repeat<SdkHistoryReadResult>(null!, nodeIds.Length).ToList();
        var errors = Enumerable.Repeat<ServiceResult>(null!, nodeIds.Length).ToList();

        nm.HistoryRead(
            context,
            new ReadRawModifiedDetails
            {
                StartTime = DateTime.UtcNow.AddHours(-1),
                EndTime = DateTime.UtcNow,
                NumValuesPerNode = 10,
                IsReadModified = modified,
            },
            TimestampsToReturn.Both,
            releaseContinuationPoints: false,
            nodesToRead,
            results,
            errors);

        return (results, errors);
    }

    private static DataPlaneAuthorizer Authorizer(
        bool enabled,
        NodeAcl grant,
        IReadOnlyDictionary<AclScopeRef, IReadOnlyList<NodeAclPath>>? scopePaths = null)
    {
        var state = new DataPlaneAuthorityState();
        state.Apply(Cluster, "rev-1", [], [grant],
            scopePaths ?? new Dictionary<AclScopeRef, IReadOnlyList<NodeAclPath>>());
        return new DataPlaneAuthorizer(
            state, new TriePermissionEvaluator(state.Tries), enabled, NullLogger.Instance);
    }

    private static NodeAcl GrantOn(NodePermissions flags) => new()
    {
        NodeAclId = "acl-cluster",
        ClusterId = Cluster,
        Principal = Principal,
        ScopeKind = NodeAclScopeKind.Cluster,
        PermissionFlags = flags,
    };

    private static RoleCarryingUserIdentity Identity() =>
        new(new UserNameIdentityToken { UserName = "apikey" }, [], Principal, apiKeyId: null);

    private async Task<(OpcUaApplicationHost Host, OtOpcUaSdkServer Server)> BootAsync()
    {
        var applicationUri = $"urn:OtOpcUa.AclTest:{Guid.NewGuid():N}";
        var started = await OpcUaHostStart.StartAsync(
            port => new OpcUaApplicationHost(
                new OpcUaApplicationHostOptions
                {
                    ApplicationName = "OtOpcUa.AclTest",
                    ApplicationUri = applicationUri,
                    OpcUaPort = port,
                    PublicHostname = "localhost",
                    PkiStoreRoot = _pkiRoot,
                },
                NullLogger<OpcUaApplicationHost>.Instance),
            () => new OtOpcUaSdkServer(), Ct);
        var host = started.Host;
        var server = started.Server;
        return (host, server);
    }

    /// <summary>Cleans up the PKI root directory.</summary>
    public void Dispose()
    {
        if (Directory.Exists(_pkiRoot))
        {
            try { Directory.Delete(_pkiRoot, recursive: true); }
            catch (IOException) { /* best effort */ }
        }
    }
}