namespace ZB.MOM.WW.ScadaBridge.ClusterInfrastructure;
///
/// Cluster configuration model, bound from the ScadaBridge:Cluster section
/// of appsettings.json via the Options pattern.
///
/// This project owns the cluster configuration contract. The actual
/// Akka.NET bootstrap — building the HOCON from these values, starting the
/// ActorSystem, configuring the split-brain resolver and wiring
/// CoordinatedShutdown — lives in ZB.MOM.WW.ScadaBridge.Host
/// (see Component-ClusterInfrastructure.md → "Implementation Note — Code Placement").
///
///
/// Node-identity settings (remoting hostname/port, cluster role, site identifier,
/// gRPC port) are deliberately not here — they are owned by
/// ZB.MOM.WW.ScadaBridge.Host.NodeOptions (ScadaBridge:Node section). Local SQLite
/// storage paths are owned by the database / store-and-forward options. This class
/// holds only the cluster-formation and failure-detection settings shared by every node.
///
///
public class ClusterOptions
{
// The previous `public const string SectionName = "ScadaBridge:Cluster";`
// was documented as "single source of truth so binding sites do not hard-code the
// magic string" but no caller ever read it — the Host's SiteServiceRegistration and
// StartupValidator both hard-code the literal directly. Wiring those binding sites
// to reference the constant lives in the Host's edit scope (a separate code-review
// task); rather than carry a public constant whose guarantee the code does not
// deliver, the constant is removed and the literal stays in the Host until the
// Host-side wiring is done. If a future Host change wants the constant back, add it
// when the binding sites can be updated in the same commit.
///
/// Akka.NET cluster seed nodes. Both nodes are seed nodes — each node lists
/// itself and its partner — so either can start first and form the cluster.
/// Must contain at least one entry.
///
public List SeedNodes { get; set; } = new();
///
/// Split-brain resolver strategy. Must be keep-oldest for the two-node
/// clusters ScadaBridge uses: quorum strategies (keep-majority,
/// static-quorum) cannot distinguish a crash from a partition with only
/// two nodes and would shut down the whole cluster.
///
public string SplitBrainResolverStrategy { get; set; } = "keep-oldest";
///
/// Time the cluster membership must remain stable before the split-brain
/// resolver acts to down unreachable nodes. Must be positive. Default 15s.
///
public TimeSpan StableAfter { get; set; } = TimeSpan.FromSeconds(15);
///
/// Frequency of cluster failure-detector heartbeat messages between nodes.
/// Must be well below . Default 2s.
///
public TimeSpan HeartbeatInterval { get; set; } = TimeSpan.FromSeconds(2);
///
/// Time without a heartbeat before a node is considered unreachable
/// (Akka's acceptable-heartbeat-pause). Default 10s.
///
public TimeSpan FailureDetectionThreshold { get; set; } = TimeSpan.FromSeconds(10);
///
/// Akka's min-nr-of-members. Must be 1: after failover only one
/// node runs, and a value of 2 blocks the cluster singleton (Site Runtime
/// Deployment Manager) — and therefore all data collection — indefinitely.
///
public int MinNrOfMembers { get; set; } = 1;
///
/// The keep-oldest resolver's down-if-alone flag. When true (the
/// design-doc requirement), the oldest node downs itself if it finds it has no
/// other reachable members, rather than running as an isolated single-node cluster.
///
public bool DownIfAlone { get; set; } = true;
///
/// Acknowledges a deliberate single-node deployment: permits exactly one seed
/// node (normally ≥2 are required so either node can start first). Without this
/// flag a single-node install must list a phantom second seed, which the node
/// dials forever — log noise and a defeated validation intent (review 01).
///
public bool AllowSingleNodeCluster { get; set; }
}