using Akka.Actor;
using Akka.Event;
using ScadaLink.Commons.Interfaces.Protocol;
using ScadaLink.Commons.Messages.DataConnection;
using ScadaLink.HealthMonitoring;
using ScadaLink.SiteEventLogging;

namespace ScadaLink.DataConnectionLayer.Actors;

/// <summary>
/// WP-34: Protocol extensibility — manages DataConnectionActor instances.
/// Routes messages to the correct connection actor based on connection name.
/// Adding a new protocol = implement IDataConnection + register with IDataConnectionFactory.
/// </summary>
public class DataConnectionManagerActor : ReceiveActor
{
    private readonly ILoggingAdapter _log = Context.GetLogger();
    private readonly IDataConnectionFactory _factory;
    private readonly DataConnectionOptions _options;
    private readonly ISiteHealthCollector _healthCollector;
    private readonly ISiteEventLogger? _siteEventLogger;
    private readonly Dictionary<string, IActorRef> _connectionActors = new();

    public DataConnectionManagerActor(
        IDataConnectionFactory factory,
        DataConnectionOptions options,
        ISiteHealthCollector healthCollector,
        ISiteEventLogger? siteEventLogger = null)
    {
        _factory = factory;
        _options = options;
        _healthCollector = healthCollector;
        _siteEventLogger = siteEventLogger;

        Receive<CreateConnectionCommand>(HandleCreateConnection);
        Receive<SubscribeTagsRequest>(HandleRoute);
        Receive<UnsubscribeTagsRequest>(HandleRoute);
        Receive<WriteTagRequest>(HandleRouteWrite);
        Receive<RemoveConnectionCommand>(HandleRemoveConnection);
        Receive<GetAllHealthReports>(HandleGetAllHealthReports);
    }

    private void HandleCreateConnection(CreateConnectionCommand command)
    {
        if (_connectionActors.ContainsKey(command.ConnectionName))
        {
            _log.Warning("Connection {0} already exists", command.ConnectionName);
            return;
        }

        // WP-34: Factory creates the correct adapter based on protocol type
        var adapter = _factory.Create(command.ProtocolType, command.PrimaryConnectionDetails);

        var props = Props.Create(() => new DataConnectionActor(
            command.ConnectionName, adapter, _options, _healthCollector,
            _factory, command.ProtocolType,
            command.PrimaryConnectionDetails,
            command.BackupConnectionDetails,
            command.FailoverRetryCount,
            _siteEventLogger));

        // Sanitize name for Akka actor path (replace spaces and invalid chars)
        var actorName = new string(command.ConnectionName
            .Select(c => char.IsLetterOrDigit(c) || "-_.*$+:@&=,!~';()".Contains(c) ? c : '-')
            .ToArray());
        var actorRef = Context.ActorOf(props, actorName);
        _connectionActors[command.ConnectionName] = actorRef;

        _log.Info("Created DataConnectionActor for {0} (protocol={1})",
            command.ConnectionName, command.ProtocolType);
    }

    private void HandleRoute(SubscribeTagsRequest request)
    {
        if (_connectionActors.TryGetValue(request.ConnectionName, out var actor))
            actor.Forward(request);
        else
        {
            _log.Warning("No connection actor for {0}", request.ConnectionName);
            Sender.Tell(new SubscribeTagsResponse(
                request.CorrelationId, request.InstanceUniqueName, false,
                $"Unknown connection: {request.ConnectionName}", DateTimeOffset.UtcNow));
        }
    }

    private void HandleRoute(UnsubscribeTagsRequest request)
    {
        if (_connectionActors.TryGetValue(request.ConnectionName, out var actor))
            actor.Forward(request);
        else
            _log.Warning("No connection actor for {0} during unsubscribe", request.ConnectionName);
    }

    private void HandleRouteWrite(WriteTagRequest request)
    {
        if (_connectionActors.TryGetValue(request.ConnectionName, out var actor))
            actor.Forward(request);
        else
        {
            _log.Warning("No connection actor for {0}", request.ConnectionName);
            Sender.Tell(new WriteTagResponse(
                request.CorrelationId, false,
                $"Unknown connection: {request.ConnectionName}", DateTimeOffset.UtcNow));
        }
    }

    private void HandleRemoveConnection(RemoveConnectionCommand command)
    {
        if (_connectionActors.TryGetValue(command.ConnectionName, out var actor))
        {
            Context.Stop(actor);
            _connectionActors.Remove(command.ConnectionName);
            _healthCollector.RemoveConnection(command.ConnectionName);
            _log.Info("Removed DataConnectionActor for {0}", command.ConnectionName);
        }
    }

    private void HandleGetAllHealthReports(GetAllHealthReports _)
    {
        // Forward health report requests to all connection actors
        foreach (var actor in _connectionActors.Values)
        {
            actor.Forward(new DataConnectionActor.GetHealthReport());
        }
    }

    /// <summary>
    /// OneForOneStrategy with Resume for connection actors.
    ///
    /// DataConnectionLayer-002: a DataConnectionActor is a long-lived, stateful
    /// coordinator — its in-memory subscription registry (_subscriptionsByInstance,
    /// _subscriptionIds, _subscribers) is the only record of which Instance Actors
    /// subscribed to which tags, and there is no durable store to rebuild it from.
    /// Restart would create a fresh instance and silently discard that registry,
    /// breaking the design doc's "transparent re-subscribe" guarantee (WP-10):
    /// subscribers would never be re-subscribed and would sit at stale quality with
    /// no error. Resume keeps the actor instance and its state intact, so a transient
    /// exception in a message handler does not lose subscription state. The actor's
    /// own Become/Stash reconnect state machine already recovers connection-level
    /// faults, so it does not need a restart to re-establish the connection.
    /// This matches the ScadaLink convention of Resume for coordinator actors.
    /// </summary>
    protected override SupervisorStrategy SupervisorStrategy()
    {
        return new OneForOneStrategy(
            maxNrOfRetries: 10,
            withinTimeRange: TimeSpan.FromMinutes(1),
            decider: Decider.From(ex =>
            {
                _log.Warning(ex, "DataConnectionActor threw exception, resuming (subscription state preserved)");
                return Directive.Resume;
            }));
    }
}

/// <summary>
/// Command to remove a data connection actor.
/// </summary>
public record RemoveConnectionCommand(string ConnectionName);

/// <summary>
/// Request for health reports from all active connections.
/// </summary>
public record GetAllHealthReports;