using Akka.Actor;
using Akka.Cluster;
using Microsoft.Extensions.Diagnostics.HealthChecks;

namespace ZB.MOM.WW.OtOpcUa.Host.Health;

public sealed class AkkaClusterHealthCheck : IHealthCheck
{
    private readonly ActorSystem _system;

    /// <summary>
    /// Initializes a new instance of the AkkaClusterHealthCheck class.
    /// </summary>
    /// <param name="system">The Akka actor system to check cluster health for.</param>
    public AkkaClusterHealthCheck(ActorSystem system)
    {
        _system = system;
    }

    /// <summary>
    /// Checks the health of the Akka cluster asynchronously.
    /// </summary>
    /// <param name="context">The health check context.</param>
    /// <param name="cancellationToken">Cancellation token.</param>
    public Task<HealthCheckResult> CheckHealthAsync(HealthCheckContext context, CancellationToken cancellationToken = default)
    {
        var cluster = Akka.Cluster.Cluster.Get(_system);
        var selfUp = cluster.State.Members.Any(m =>
            m.Address == cluster.SelfAddress && m.Status == MemberStatus.Up);

        return Task.FromResult(selfUp
            ? HealthCheckResult.Healthy($"Self Up; {cluster.State.Members.Count} member(s)")
            : HealthCheckResult.Degraded("Self not yet Up in cluster"));
    }
}