using Akka.Actor;
using Akka.Cluster.Tools.PublishSubscribe;
using Akka.Event;
using Microsoft.EntityFrameworkCore;
using ZB.MOM.WW.OtOpcUa.Commons.Messages.Admin;
using ZB.MOM.WW.OtOpcUa.Commons.Messages.Deploy;
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;

namespace ZB.MOM.WW.OtOpcUa.ControlPlane.AdminOperations;

/// <summary>
/// Cluster-singleton admin operations actor. Owns the "snapshot the live-edit state and start
/// a deployment" workflow plus (eventually) all mutating live-edit ops invoked by the admin UI.
/// Routed to via <see cref="Commons.Interfaces.IAdminOperationsClient"/> from anywhere in the cluster.
/// </summary>
public sealed class AdminOperationsActor : ReceiveActor
{
    private readonly IDbContextFactory<OtOpcUaConfigDbContext> _dbFactory;
    private readonly IActorRef _coordinator;
    private readonly IReadOnlyDictionary<string, IDriverProbe> _probesByType;
    private readonly ILoggingAdapter _log = Context.GetLogger();

    /// <summary>Creates actor props for the admin operations actor.</summary>
    /// <param name="dbFactory">Factory for creating config database contexts.</param>
    /// <param name="coordinator">Reference to the deployment coordinator actor.</param>
    /// <param name="probes">Driver probes registered in DI; keyed by DriverType (case-insensitive).</param>
    /// <returns>Props configured to create an AdminOperationsActor.</returns>
    public static Props Props(
        IDbContextFactory<OtOpcUaConfigDbContext> dbFactory,
        IActorRef coordinator,
        IEnumerable<IDriverProbe> probes) =>
        Akka.Actor.Props.Create(() => new AdminOperationsActor(dbFactory, coordinator, probes));

    /// <summary>Initializes a new instance of the AdminOperationsActor.</summary>
    /// <param name="dbFactory">Factory for creating config database contexts.</param>
    /// <param name="coordinator">Reference to the deployment coordinator actor.</param>
    /// <param name="probes">Driver probes registered in DI; keyed by DriverType (case-insensitive).</param>
    public AdminOperationsActor(
        IDbContextFactory<OtOpcUaConfigDbContext> dbFactory,
        IActorRef coordinator,
        IEnumerable<IDriverProbe> probes)
    {
        _dbFactory = dbFactory;
        _coordinator = coordinator;
        _probesByType = probes.ToDictionary(p => p.DriverType, StringComparer.OrdinalIgnoreCase);

        ReceiveAsync<StartDeployment>(HandleStartDeploymentAsync);
        ReceiveAsync<TestDriverConnect>(HandleTestDriverConnectAsync);
        ReceiveAsync<RestartDriver>(HandleRestartDriverAsync);
        ReceiveAsync<ReconnectDriver>(HandleReconnectDriverAsync);
    }

    private async Task HandleStartDeploymentAsync(StartDeployment msg)
    {
        var replyTo = Sender;
        try
        {
            await using var db = await _dbFactory.CreateDbContextAsync();

            // Refuse if any deployment is already in flight — keeps the coordinator's state
            // unambiguous. The UI is expected to wait for the in-flight one to seal or fail.
            var inflight = await db.Deployments
                .Where(d => d.Status == DeploymentStatus.Dispatching || d.Status == DeploymentStatus.AwaitingApplyAcks)
                .Select(d => d.DeploymentId)
                .FirstOrDefaultAsync();
            if (inflight != Guid.Empty)
            {
                replyTo.Tell(new StartDeploymentResult(
                    StartDeploymentOutcome.AnotherDeploymentInFlight,
                    DeploymentId: new DeploymentId(inflight),
                    RevisionHash: null,
                    Message: $"Deployment {inflight:N} is still in flight.",
                    msg.CorrelationId));
                return;
            }

            var artifact = await ConfigComposer.SnapshotAndFlattenAsync(db);
            var deploymentId = DeploymentId.NewId();
            var revHash = RevisionHash.Parse(artifact.RevisionHash);

            db.Deployments.Add(new Deployment
            {
                DeploymentId = deploymentId.Value,
                RevisionHash = artifact.RevisionHash,
                Status = DeploymentStatus.Dispatching,
                CreatedBy = msg.CreatedBy,
                ArtifactBlob = artifact.Blob,
            });

            // Marker ConfigEdit row so the audit timeline shows the deployment snapshot.
            db.ConfigEdits.Add(new ConfigEdit
            {
                EntityType = "Deployment",
                EntityId = deploymentId.Value,
                FieldsJson = $"{{\"revisionHash\":\"{artifact.RevisionHash}\",\"sizeBytes\":{artifact.Blob.Length}}}",
                EditedBy = msg.CreatedBy,
                SourceNode = Akka.Cluster.Cluster.Get(Context.System).SelfAddress.Host ?? "unknown",
            });

            await db.SaveChangesAsync();

            _coordinator.Tell(new DispatchDeployment(deploymentId, revHash, msg.CorrelationId));

            replyTo.Tell(new StartDeploymentResult(
                StartDeploymentOutcome.Accepted,
                deploymentId,
                revHash,
                Message: null,
                msg.CorrelationId));
        }
        catch (Exception ex)
        {
            _log.Error(ex, "StartDeployment failed for {CreatedBy}", msg.CreatedBy);
            replyTo.Tell(new StartDeploymentResult(
                StartDeploymentOutcome.Rejected,
                DeploymentId: null,
                RevisionHash: null,
                Message: ex.Message,
                msg.CorrelationId));
        }
    }

    private async Task HandleTestDriverConnectAsync(TestDriverConnect msg)
    {
        var replyTo = Sender;
        if (!_probesByType.TryGetValue(msg.DriverType, out var probe))
        {
            replyTo.Tell(new TestDriverConnectResult(
                false,
                $"No probe registered for driver type '{msg.DriverType}'.",
                null,
                msg.CorrelationId));
            return;
        }

        var clampedSec = Math.Clamp(msg.TimeoutSeconds, 1, 60);
        var timeout = TimeSpan.FromSeconds(clampedSec);
        using var cts = new CancellationTokenSource(timeout);

        var sw = System.Diagnostics.Stopwatch.StartNew();
        try
        {
            var result = await probe.ProbeAsync(msg.ConfigJson, timeout, cts.Token);
            sw.Stop();
            replyTo.Tell(new TestDriverConnectResult(
                result.Ok,
                result.Message,
                result.Ok ? sw.Elapsed.TotalMilliseconds : (double?)null,
                msg.CorrelationId));
        }
        catch (OperationCanceledException)
        {
            replyTo.Tell(new TestDriverConnectResult(
                false,
                $"Probe timed out after {clampedSec}s.",
                null,
                msg.CorrelationId));
        }
        catch (Exception ex)
        {
            _log.Error(ex, "Probe for {DriverType} threw", msg.DriverType);
            replyTo.Tell(new TestDriverConnectResult(
                false,
                ex.Message,
                null,
                msg.CorrelationId));
        }
    }

    private async Task HandleRestartDriverAsync(RestartDriver msg)
    {
        var replyTo = Sender;
        try
        {
            // Broadcast to every DriverHostActor on every node via the driver-control DPS topic.
            // Only the host that owns the instance will act; others ignore it (id not found in _children).
            DistributedPubSub.Get(Context.System).Mediator.Tell(new Publish(DriverControlTopic.Name, msg));

            await using var db = await _dbFactory.CreateDbContextAsync();
            db.ConfigEdits.Add(new ConfigEdit
            {
                EntityType = "DriverInstance",
                EntityId = Guid.TryParse(msg.DriverInstanceId, out var guid) ? guid : Guid.Empty,
                FieldsJson = $"{{\"op\":\"restart\",\"driverInstanceId\":{System.Text.Json.JsonSerializer.Serialize(msg.DriverInstanceId)}}}",
                EditedBy = msg.ActorByUserName,
                SourceNode = Akka.Cluster.Cluster.Get(Context.System).SelfAddress.Host ?? "unknown",
            });
            await db.SaveChangesAsync();

            _log.Info("AdminOps: RestartDriver dispatched for {DriverInstanceId} by {User}",
                msg.DriverInstanceId, msg.ActorByUserName);
            replyTo.Tell(new RestartDriverResult(true, null, msg.CorrelationId));
        }
        catch (Exception ex)
        {
            _log.Error(ex, "AdminOps: RestartDriver failed for {DriverInstanceId}", msg.DriverInstanceId);
            replyTo.Tell(new RestartDriverResult(false, ex.Message, msg.CorrelationId));
        }
    }

    private async Task HandleReconnectDriverAsync(ReconnectDriver msg)
    {
        var replyTo = Sender;
        try
        {
            // Broadcast to every DriverHostActor; only the one owning the instance reacts.
            DistributedPubSub.Get(Context.System).Mediator.Tell(new Publish(DriverControlTopic.Name, msg));

            await using var db = await _dbFactory.CreateDbContextAsync();
            db.ConfigEdits.Add(new ConfigEdit
            {
                EntityType = "DriverInstance",
                EntityId = Guid.TryParse(msg.DriverInstanceId, out var guid) ? guid : Guid.Empty,
                FieldsJson = $"{{\"op\":\"reconnect\",\"driverInstanceId\":{System.Text.Json.JsonSerializer.Serialize(msg.DriverInstanceId)}}}",
                EditedBy = msg.ActorByUserName,
                SourceNode = Akka.Cluster.Cluster.Get(Context.System).SelfAddress.Host ?? "unknown",
            });
            await db.SaveChangesAsync();

            _log.Info("AdminOps: ReconnectDriver dispatched for {DriverInstanceId} by {User}",
                msg.DriverInstanceId, msg.ActorByUserName);
            replyTo.Tell(new ReconnectDriverResult(true, null, msg.CorrelationId));
        }
        catch (Exception ex)
        {
            _log.Error(ex, "AdminOps: ReconnectDriver failed for {DriverInstanceId}", msg.DriverInstanceId);
            replyTo.Tell(new ReconnectDriverResult(false, ex.Message, msg.CorrelationId));
        }
    }
}