using Prometheus;

public sealed class ClinicalMetrics
{
    // --- Counters ---

    // Labeled by observation_code and source so clinicians can see which device types
    // and which codes dominate the ingest volume.
    public readonly Counter ObservationsIngestedTotal = Metrics.CreateCounter(
        "observations_ingested_total",
        "Total observations ingested, labeled by observation code and source.",
        labelNames: new[] { "observation_code", "source" });

    // Labeled by alert_type (THRESHOLD_BREACH, SEPSIS_WARNING) and severity
    // (Critical, Warning) so the dashboard can show Critical vs Warning rates separately.
    public readonly Counter ClinicalAlertsTotal = Metrics.CreateCounter(
        "clinical_alerts_total",
        "Total clinical alerts generated, labeled by type and severity.",
        labelNames: new[] { "alert_type", "severity" });

    // Incremented only when INSERT WHERE NOT EXISTS succeeds — duplicate-suppressed
    // SIRS detections do not count. This is the true detection rate, not the evaluation rate.
    public readonly Counter SirsDetectionsTotal = Metrics.CreateCounter(
        "sirs_detections_total",
        "Total SEPSIS_WARNING alerts generated by the sepsis detection engine.");

    // Incremented by EscalationWorkerService when it processes a message from
    // alerts.escalation.queue. A rising escalations_total is the strongest operational
    // signal that critical alerts are not being acknowledged by the attending physician.
    public readonly Counter EscalationsTotal = Metrics.CreateCounter(
        "escalations_total",
        "Total alert escalations processed through the DLQ escalation path.");

    // --- Histograms ---

    // Measures the full ingest transaction: Redis cache lookup + alert evaluation +
    // outbox write + COMMIT. The 99th percentile matters for patient safety —
    // a slow ingest path delays the critical alert creation.
    public readonly Histogram ObservationIngestDuration = Metrics.CreateHistogram(
        "observation_ingest_duration_seconds",
        "Ingest transaction duration from request receipt to COMMIT.",
        new HistogramConfiguration
        {
            Buckets = new[] { 0.005, 0.01, 0.025, 0.05, 0.1, 0.25, 0.5, 1.0 }
        });

    // --- Gauges (set by background collectors, not incremented inline) ---

    // The most clinically significant panel. A non-zero value means a patient's
    // critical alert has gone unacknowledged for more than 5 minutes.
    // In a real deployment this panel drives an on-call pager alert at the nurse station.
    public readonly Gauge AlertsUnacknowledgedGauge = Metrics.CreateGauge(
        "alerts_unacknowledged_gauge",
        "Count of open CRITICAL alerts older than 5 minutes with no acknowledgment.");

    // Per consumer group so the dashboard can show whether es-indexer, sepsis-engine,
    // or data-lake-writer is falling behind the observation stream.
    public readonly Gauge KafkaConsumerLag = Metrics.CreateGauge(
        "kafka_consumer_lag",
        "Approximate consumer group lag in messages, labeled by consumer group.",
        labelNames: new[] { "consumer_group" });

    // An outbox that is growing means the relay is not keeping up or Kafka is unavailable.
    // In a patient safety system, a growing outbox delays alert delivery to all consumers.
    public readonly Gauge OutboxPendingEvents = Metrics.CreateGauge(
        "outbox_pending_events",
        "Count of outbox events not yet relayed to Kafka.");
}