lmxopcua/src/ZB.MOM.WW.LmxOpcUa.Host/Status/HealthCheckService.cs

using ZB.MOM.WW.LmxOpcUa.Host.Domain;
using ZB.MOM.WW.LmxOpcUa.Host.Metrics;

namespace ZB.MOM.WW.LmxOpcUa.Host.Status
{
    /// <summary>
    /// Determines health status based on connection state and operation success rates. (DASH-003)
    /// </summary>
    public class HealthCheckService
    {
        public HealthInfo CheckHealth(ConnectionState connectionState, PerformanceMetrics? metrics)
        {
            // Rule 1: Not connected → Unhealthy
            if (connectionState != ConnectionState.Connected)
            {
                return new HealthInfo
                {
                    Status = "Unhealthy",
                    Message = $"MXAccess not connected (state: {connectionState})",
                    Color = "red"
                };
            }

            // Rule 2: Success rate < 50% with > 100 ops → Degraded
            if (metrics != null)
            {
                var stats = metrics.GetStatistics();
                foreach (var kvp in stats)
                {
                    if (kvp.Value.TotalCount > 100 && kvp.Value.SuccessRate < 0.5)
                    {
                        return new HealthInfo
                        {
                            Status = "Degraded",
                            Message = $"{kvp.Key} success rate is {kvp.Value.SuccessRate:P0} ({kvp.Value.TotalCount} ops)",
                            Color = "yellow"
                        };
                    }
                }
            }

            // Rule 3: All good
            return new HealthInfo
            {
                Status = "Healthy",
                Message = "All systems operational",
                Color = "green"
            };
        }

        public bool IsHealthy(ConnectionState connectionState, PerformanceMetrics? metrics)
        {
            var health = CheckHealth(connectionState, metrics);
            return health.Status != "Unhealthy";
        }
    }
}