using System.Collections.Concurrent;
using System.Text.Json;
using Akka.Actor;
using Microsoft.EntityFrameworkCore;
using Shouldly;
using Xunit;
using ZB.MOM.WW.OtOpcUa.Commons.Engines;
using ZB.MOM.WW.OtOpcUa.Commons.Messages.Deploy;
using ZB.MOM.WW.OtOpcUa.Commons.Messages.Fleet;
using ZB.MOM.WW.OtOpcUa.Commons.Messages.Redundancy;
using ZB.MOM.WW.OtOpcUa.Commons.Types;
using ZB.MOM.WW.OtOpcUa.Configuration;
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.Runtime.Drivers;
using ZB.MOM.WW.OtOpcUa.Runtime.OpcUa;
using ZB.MOM.WW.OtOpcUa.Runtime.Tests.Harness;

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

/// <summary>
///     v3 Batch 4 (B4-WP3) — inbound operator-write routing through EITHER NodeId. A
///     <see cref="DriverHostActor.RouteNodeWrite"/> carries the FULL ns-qualified NodeId string (the node
///     manager's write hook passes <c>node.NodeId.ToString()</c>); the host normalises it to the bare id and
///     resolves the <c>NodeId → (DriverInstanceId, RawPath)</c> reverse map — populated in
///     <c>PushDesiredSubscriptions</c> for BOTH the raw NodeId AND every referencing UNS NodeId — gates on the
///     driver PRIMARY, and forwards a <see cref="DriverInstanceActor.WriteAttribute"/> carrying the tag's
///     <c>RawPath</c> to the driver child. So a write to the raw node and a write to the referencing UNS node
///     both reach the SAME driver point (they share the driver ref).
///     <para>
///         Drives a real apply (Enabled Modbus driver ⇒ a real <see cref="DriverInstanceActor"/> child backed
///         by a recording driver), then routes writes and asserts the forwarded wire-ref + the primary gate.
///     </para>
/// </summary>
public sealed class DriverHostActorWriteRoutingTests : RuntimeActorTestBase
{
    private static readonly NodeId TestNode = NodeId.Parse("driver-wr-test");
    private static readonly RevisionHash RevA = RevisionHash.Parse(new string('a', 64));
    private static readonly TimeSpan Timeout = TimeSpan.FromSeconds(5);

    // The single seeded raw tag + its UNS reference.
    private const string RawPath = "Plant/Modbus/dev1/speed";
    private const string UnsNodeId = "filling/line1/station1/speed";

    /// <summary>On the PRIMARY, a RouteNodeWrite for the ns-qualified UNS NodeId resolves to the raw tag's
    /// driver ref and forwards the write keyed by the tag's RawPath (dual-NodeId write routing).</summary>
    [Fact]
    public void Primary_routes_write_via_uns_nodeid_to_driver_by_rawpath()
    {
        var db = NewInMemoryDbFactory();
        var recorder = new RecordingDriverFactory("Modbus");
        var deploymentId = SeedV3Deployment(db, RevA);

        var actor = SpawnHostAndApply(db, deploymentId, recorder);

        var asker = CreateTestProbe();
        // The node manager passes the FULL ns-qualified id; the host must normalise + resolve it.
        actor.Tell(new DriverHostActor.RouteNodeWrite($"ns=3;s={UnsNodeId}", 123.0), asker.Ref);

        asker.ExpectMsg<DriverHostActor.NodeWriteResult>(Timeout).Success.ShouldBeTrue();
        AwaitAssert(() =>
        {
            recorder.Writes.Count.ShouldBe(1);
            recorder.Writes[0].FullReference.ShouldBe(RawPath); // the driver writes by RawPath, not the UNS id
            recorder.Writes[0].Value.ShouldBe(123.0);
        }, duration: Timeout);
    }

    /// <summary>On the PRIMARY, a RouteNodeWrite for the ns-qualified RAW NodeId resolves to the same driver
    /// ref and forwards the write keyed by the RawPath.</summary>
    [Fact]
    public void Primary_routes_write_via_raw_nodeid_to_driver_by_rawpath()
    {
        var db = NewInMemoryDbFactory();
        var recorder = new RecordingDriverFactory("Modbus");
        var deploymentId = SeedV3Deployment(db, RevA);

        var actor = SpawnHostAndApply(db, deploymentId, recorder);

        var asker = CreateTestProbe();
        actor.Tell(new DriverHostActor.RouteNodeWrite($"ns=2;s={RawPath}", 456.0), asker.Ref);

        asker.ExpectMsg<DriverHostActor.NodeWriteResult>(Timeout).Success.ShouldBeTrue();
        AwaitAssert(() =>
        {
            recorder.Writes.Count.ShouldBe(1);
            recorder.Writes[0].FullReference.ShouldBe(RawPath);
            recorder.Writes[0].Value.ShouldBe(456.0);
        }, duration: Timeout);
    }

    /// <summary>On a SECONDARY, RouteNodeWrite (via the UNS NodeId) replies "not primary" and the driver
    /// receives NO write — the primary gate fires before the reverse-map lookup.</summary>
    [Fact]
    public void Secondary_rejects_write_and_does_not_forward_to_driver()
    {
        var db = NewInMemoryDbFactory();
        var recorder = new RecordingDriverFactory("Modbus");
        var deploymentId = SeedV3Deployment(db, RevA);

        var actor = SpawnHostAndApply(db, deploymentId, recorder);

        actor.Tell(new RedundancyStateChanged(
            new[]
            {
                new NodeRedundancyState(TestNode, RedundancyRole.Secondary,
                    IsClusterLeader: false, IsRoleLeaderForDriver: false, AsOfUtc: DateTime.UtcNow),
            },
            CorrelationId.NewId()));

        var asker = CreateTestProbe();
        actor.Tell(new DriverHostActor.RouteNodeWrite($"ns=3;s={UnsNodeId}", 123.0), asker.Ref);

        var result = asker.ExpectMsg<DriverHostActor.NodeWriteResult>(Timeout);
        result.Success.ShouldBeFalse();
        result.Reason.ShouldBe("not primary");
        recorder.Writes.ShouldBeEmpty();
    }

    /// <summary>An unknown NodeId (no reverse-map entry) replies failure and writes nothing.</summary>
    [Fact]
    public void Unknown_node_id_replies_failure()
    {
        var db = NewInMemoryDbFactory();
        var recorder = new RecordingDriverFactory("Modbus");
        var deploymentId = SeedV3Deployment(db, RevA);

        var actor = SpawnHostAndApply(db, deploymentId, recorder);

        var asker = CreateTestProbe();
        actor.Tell(new DriverHostActor.RouteNodeWrite("ns=3;s=filling/line1/station1/does-not-exist", 1.0), asker.Ref);

        var result = asker.ExpectMsg<DriverHostActor.NodeWriteResult>(Timeout);
        result.Success.ShouldBeFalse();
        result.Reason.ShouldNotBeNull();
        recorder.Writes.ShouldBeEmpty();
    }

    /// <summary>A RouteNodeWrite arriving while the host is Stale (config DB unreachable) fast-fails with an
    /// immediate negative reply mentioning "stale".</summary>
    [Fact]
    public void Stale_host_fast_fails_route_node_write()
    {
        var db = new ThrowingDbFactory();
        var coordinator = CreateTestProbe();
        var actor = Sys.ActorOf(DriverHostActor.Props(
            db, TestNode, coordinator.Ref,
            localRoles: new HashSet<string> { "driver" }));

        var asker = CreateTestProbe();
        actor.Tell(new DriverHostActor.RouteNodeWrite($"ns=3;s={UnsNodeId}", 123.0), asker.Ref);

        var result = asker.ExpectMsg<DriverHostActor.NodeWriteResult>(TimeSpan.FromSeconds(2));
        result.Success.ShouldBeFalse();
        result.Reason.ShouldNotBeNull();
        result.Reason!.ShouldContain("stale");
    }

    /// <summary>Spawns the host with the recording driver factory, dispatches the deployment, and waits for
    /// the Applied ACK so the reverse-map build in PushDesiredSubscriptions has completed before routing a
    /// write. No OPC UA / mux probes are wired — the write path doesn't depend on the publish actor.</summary>
    private IActorRef SpawnHostAndApply(
        IDbContextFactory<OtOpcUaConfigDbContext> db, DeploymentId deploymentId, IDriverFactory factory)
    {
        var coordinator = CreateTestProbe();
        var actor = Sys.ActorOf(DriverHostActor.Props(
            db, TestNode, coordinator.Ref,
            driverFactory: factory,
            localRoles: new HashSet<string> { "driver" }));

        actor.Tell(new DispatchDeployment(deploymentId, RevA, CorrelationId.NewId()));
        coordinator.ExpectMsg<ApplyAck>(Timeout).Outcome.ShouldBe(ApplyAckOutcome.Applied);
        return actor;
    }

    /// <summary>Seeds a Sealed v3 deployment: RawFolder "Plant" → DriverInstance "drv-1" (Modbus, ENABLED so a
    /// real child spawns) → Device "dev1" → Tag "speed" (RawPath <c>Plant/Modbus/dev1/speed</c>, ReadWrite),
    /// projected into equipment <c>filling/line1/station1</c> by a UnsTagReference (UNS NodeId
    /// <c>filling/line1/station1/speed</c>).</summary>
    private static DeploymentId SeedV3Deployment(IDbContextFactory<OtOpcUaConfigDbContext> db, RevisionHash rev)
    {
        var artifact = JsonSerializer.SerializeToUtf8Bytes(new
        {
            RawFolders = new[] { new { RawFolderId = "rf-plant", ParentRawFolderId = (string?)null, Name = "Plant", ClusterId = "c1" } },
            DriverInstances = new[]
            {
                new { DriverInstanceId = "drv-1", RawFolderId = "rf-plant", Name = "Modbus", DriverType = "Modbus", DriverConfig = "{}", ClusterId = "c1", Enabled = true },
            },
            Devices = new[] { new { DeviceId = "dev-1", DriverInstanceId = "drv-1", Name = "dev1", DeviceConfig = "{}" } },
            TagGroups = Array.Empty<object>(),
            Tags = new[]
            {
                new { TagId = "t-speed", DeviceId = "dev-1", TagGroupId = (string?)null, Name = "speed", DataType = "Double", AccessLevel = 1, TagConfig = "{}" },
            },
            UnsAreas = new[] { new { UnsAreaId = "a1", Name = "filling", ClusterId = "c1" } },
            UnsLines = new[] { new { UnsLineId = "l1", UnsAreaId = "a1", Name = "line1" } },
            Equipment = new[] { new { EquipmentId = "EQ-1", UnsLineId = "l1", Name = "station1", MachineCode = "M1" } },
            UnsTagReferences = new[] { new { UnsTagReferenceId = "r1", EquipmentId = "EQ-1", TagId = "t-speed", DisplayNameOverride = (string?)null } },
        });

        var id = DeploymentId.NewId();
        using var ctx = db.CreateDbContext();
        ctx.Deployments.Add(new Deployment
        {
            DeploymentId = id.Value,
            RevisionHash = rev.Value,
            Status = DeploymentStatus.Sealed,
            CreatedBy = "test",
            SealedAtUtc = DateTime.UtcNow,
            ArtifactBlob = artifact,
        });
        ctx.SaveChanges();
        return id;
    }

    /// <summary>An <see cref="IDbContextFactory{T}"/> whose CreateDbContext always throws — drives the host
    /// into the Stale path.</summary>
    private sealed class ThrowingDbFactory : IDbContextFactory<OtOpcUaConfigDbContext>
    {
        /// <inheritdoc />
        public OtOpcUaConfigDbContext CreateDbContext() =>
            throw new InvalidOperationException("config DB unreachable (test stub)");
    }

    /// <summary>Factory producing a single <see cref="RecordingDriver"/> for the supported type.</summary>
    private sealed class RecordingDriverFactory : IDriverFactory
    {
        private readonly string _supportedType;
        private readonly RecordingDriver _driver = new();
        public RecordingDriverFactory(string supportedType) { _supportedType = supportedType; }

        /// <summary>The writes the spawned driver received.</summary>
        public IReadOnlyList<WriteRequest> Writes => _driver.Writes;

        /// <inheritdoc />
        public IDriver? TryCreate(string driverType, string driverInstanceId, string driverConfigJson)
        {
            if (!string.Equals(driverType, _supportedType, StringComparison.Ordinal)) return null;
            _driver.Bind(driverInstanceId, driverType);
            return _driver;
        }

        /// <inheritdoc />
        public IReadOnlyCollection<string> SupportedTypes => new[] { _supportedType };
    }

    /// <summary>An <see cref="IDriver"/> + <see cref="IWritable"/> that records every write and returns Good.</summary>
    private sealed class RecordingDriver : IDriver, IWritable
    {
        private readonly ConcurrentQueue<WriteRequest> _writes = new();
        /// <inheritdoc />
        public string DriverInstanceId { get; private set; } = string.Empty;
        /// <inheritdoc />
        public string DriverType { get; private set; } = string.Empty;
        /// <summary>The writes received so far.</summary>
        public IReadOnlyList<WriteRequest> Writes => _writes.ToArray();
        /// <summary>Sets the identity once the factory is asked to create it.</summary>
        public void Bind(string id, string type) { DriverInstanceId = id; DriverType = type; }
        /// <inheritdoc />
        public Task InitializeAsync(string driverConfigJson, CancellationToken cancellationToken) => Task.CompletedTask;
        /// <inheritdoc />
        public Task ReinitializeAsync(string driverConfigJson, CancellationToken cancellationToken) => Task.CompletedTask;
        /// <inheritdoc />
        public Task ShutdownAsync(CancellationToken cancellationToken) => Task.CompletedTask;
        /// <inheritdoc />
        public DriverHealth GetHealth() => new(DriverState.Healthy, DateTime.UtcNow, LastError: null);
        /// <inheritdoc />
        public long GetMemoryFootprint() => 0;
        /// <inheritdoc />
        public Task FlushOptionalCachesAsync(CancellationToken cancellationToken) => Task.CompletedTask;
        /// <inheritdoc />
        public Task<IReadOnlyList<WriteResult>> WriteAsync(
            IReadOnlyList<WriteRequest> writes, CancellationToken cancellationToken)
        {
            foreach (var w in writes) _writes.Enqueue(w);
            return Task.FromResult<IReadOnlyList<WriteResult>>(
                writes.Select(_ => new WriteResult(0u)).ToArray());
        }
    }
}