namespace ScadaLink.InboundAPI;

/// <summary>
/// InboundAPI-008: abstraction the inbound API endpoint uses to determine whether
/// this node is the active (cluster-leader) central node.
///
/// The design states the inbound API is "Central cluster only (active node)" and
/// "fails over with it". A standby central node must not execute method scripts or
/// <c>Route.To()</c> calls — that can race the active node or run against stale
/// singleton state. <see cref="InboundApiEndpointFilter"/> consults this gate and
/// returns HTTP 503 from a standby so Traefik/clients only reach the live node.
///
/// The implementation lives in the Host (it needs Akka cluster state); when no
/// implementation is registered, the endpoint defaults to "allow" so non-clustered
/// hosts and tests are unaffected.
/// </summary>
public interface IActiveNodeGate
{
    /// <summary>
    /// <c>true</c> when this node is the active central node and may serve the
    /// inbound API; <c>false</c> on a standby node.
    /// </summary>
    bool IsActiveNode { get; }
}