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.OpcUa;
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.Configuration.Validation;
using ZB.MOM.WW.OtOpcUa.Core.Abstractions;
using ZB.MOM.WW.OtOpcUa.Core.Scripting;

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);
        Receive<AcknowledgeAlarmCommand>(HandleAcknowledgeAlarm);
        Receive<ShelveAlarmCommand>(HandleShelveAlarm);
    }

    /// <summary>
    ///     AdminUI Acknowledge path. Maps the control-plane command to a
    ///     <see cref="AlarmCommand"/> (<c>Operation = "Acknowledge"</c>) and publishes it onto the
    ///     cluster <c>alarm-commands</c> topic. The broadcast lands on every driver node's
    ///     <c>ScriptedAlarmHostActor</c>; only the node owning the alarm acts (ownership filter), so the
    ///     admin singleton needs no knowledge of placement. Synchronous — the publish is fire-and-forget
    ///     via the mediator, so there is no awaitable work and no DB write.
    /// </summary>
    private void HandleAcknowledgeAlarm(AcknowledgeAlarmCommand msg)
    {
        var replyTo = Sender;
        try
        {
            var alarmCmd = new AlarmCommand(
                AlarmId: msg.AlarmId,
                Operation: "Acknowledge",
                User: msg.User,
                Comment: msg.Comment,
                UnshelveAtUtc: null);

            DistributedPubSub.Get(Context.System).Mediator.Tell(new Publish(AlarmCommandsTopic.Name, alarmCmd));

            _log.Info("AdminOps: Acknowledge published for alarm {AlarmId} by {User}", msg.AlarmId, msg.User);
            replyTo.Tell(new AcknowledgeAlarmResult(true, null, msg.CorrelationId));
        }
        catch (Exception ex)
        {
            _log.Error(ex, "AdminOps: Acknowledge failed for alarm {AlarmId}", msg.AlarmId);
            replyTo.Tell(new AcknowledgeAlarmResult(false, ex.Message, msg.CorrelationId));
        }
    }

    /// <summary>
    ///     AdminUI Shelve / Unshelve path. Maps <see cref="ShelveAlarmCommand.Kind"/> to the matching
    ///     <see cref="AlarmCommand"/> operation (<c>OneShotShelve</c> / <c>TimedShelve</c> /
    ///     <c>Unshelve</c>), threading <see cref="ShelveAlarmCommand.UnshelveAtUtc"/> for the timed kind,
    ///     and publishes onto the cluster <c>alarm-commands</c> topic. Ownership filtering happens on the
    ///     owning node exactly as for Acknowledge.
    /// </summary>
    private void HandleShelveAlarm(ShelveAlarmCommand msg)
    {
        var replyTo = Sender;
        try
        {
            var (operation, unshelveAt) = msg.Kind switch
            {
                ShelveKind.OneShot => ("OneShotShelve", (DateTime?)null),
                ShelveKind.Timed => ("TimedShelve", msg.UnshelveAtUtc),
                ShelveKind.Unshelve => ("Unshelve", (DateTime?)null),
                _ => throw new ArgumentOutOfRangeException(nameof(msg), msg.Kind, "Unknown shelve kind."),
            };

            // TimedShelve requires an unshelve instant — the engine rejects it otherwise. Guard here so
            // the AdminUI gets an immediate, attributable failure instead of a silently-dropped command.
            if (msg.Kind == ShelveKind.Timed && unshelveAt is null)
            {
                replyTo.Tell(new ShelveAlarmResult(false, "TimedShelve requires UnshelveAtUtc.", msg.CorrelationId));
                return;
            }

            var alarmCmd = new AlarmCommand(
                AlarmId: msg.AlarmId,
                Operation: operation,
                User: msg.User,
                Comment: msg.Comment,
                UnshelveAtUtc: unshelveAt);

            DistributedPubSub.Get(Context.System).Mediator.Tell(new Publish(AlarmCommandsTopic.Name, alarmCmd));

            _log.Info("AdminOps: {Operation} published for alarm {AlarmId} by {User}", operation, msg.AlarmId, msg.User);
            replyTo.Tell(new ShelveAlarmResult(true, null, msg.CorrelationId));
        }
        catch (Exception ex)
        {
            _log.Error(ex, "AdminOps: Shelve ({Kind}) failed for alarm {AlarmId}", msg.Kind, msg.AlarmId);
            replyTo.Tell(new ShelveAlarmResult(false, ex.Message, msg.CorrelationId));
        }
    }

    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;
            }

            // Full pre-seal gate: run the complete DraftValidator (one pass, all rules) and reject
            // on ANY validation error. The config is now canonical — the company overlay loader emits
            // canonical EquipmentIds and the seed is clean — so every rule (UNS segments, EquipmentId
            // derivation, cross-cluster/namespace binding, driver-namespace compat, signal collisions,
            // …) gates the deploy. A green build in this repo does not prove the config is valid; this
            // is the last guard before a bad address space (or a non-derived EquipmentId) ships.
            // NOTE: a BadDuplicateExternalIdentifier rejection from the reservation pre-flight can
            // (rarely) be a false positive if an external-id reservation release has not yet been
            // committed/visible when the snapshot is read — operators seeing a spurious one should
            // check ExternalIdReservation state before re-submitting.
            var draft = await DraftSnapshotFactory.FromConfigDbAsync(db);
            var errors = DraftValidator.Validate(draft);
            if (errors.Count > 0)
            {
                var summary = string.Join("; ", errors.Select(e => $"[{e.Code}] {e.Message}"));
                _log.Warning("StartDeployment rejected ({Count} validation error(s)): {Summary}",
                    errors.Count, summary);
                replyTo.Tell(new StartDeploymentResult(
                    StartDeploymentOutcome.Rejected,
                    DeploymentId: null,
                    RevisionHash: null,
                    Message: summary,
                    msg.CorrelationId));
                return;
            }

            // Warn-only compile-cost guardrail (NEVER blocks). Each genuinely-compiled (non-passthrough)
            // script costs ~1.66 MiB RSS per node to materialize via Roslyn (measured post-A0; design doc
            // 2026-06-07). Passthrough "mirror" scripts compile to ~nothing, so they are excluded; distinct
            // sources are counted (the compile cache keys on source, so duplicates collapse to one unit).
            // This only surfaces the estimate to the operator — the DraftValidator gate above is the hard
            // reject; this advisory rides in the Accepted Message so the UI can show it.
            // advisory is declared outside the inner try so the Accepted reply below can still read it even
            // when the guardrail query throws (e.g. transient SQL). A failed estimate must NEVER block a
            // valid deploy — the outer catch is reserved for genuine seal/save failures.
            string? advisory = null;
            try
            {
                const double PerScriptMiB = 1.66; // measured post-A0 per-script RSS (design doc 2026-06-07)
                var scriptSources = await db.Scripts.AsNoTracking().Select(s => s.SourceCode).ToListAsync();
                var compiled = scriptSources
                    .Where(src => !PassthroughScript.TryMatch(src, out _))
                    .Distinct(StringComparer.Ordinal)
                    .Count();
                if (compiled > 0)
                {
                    var estMiB = compiled * PerScriptMiB;
                    _log.Warning(
                        "StartDeployment: {Compiled} script(s) will compile (~{EstMiB:F0} MiB RSS per node); ensure node mem_limit covers it",
                        compiled, estMiB);
                    advisory = $"{compiled} script(s) will compile (~{estMiB:F0} MiB/node)";
                }
            }
            catch (Exception ex)
            {
                // Guardrail is advisory-only — a failed estimate must never block a valid deploy.
                _log.Warning(ex, "StartDeployment: script compile-cost estimate failed; advisory skipped");
                advisory = null;
            }

            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: advisory,
                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));
        }
    }
}