package observability

import (
	"context"
	"time"

	"github.com/jackc/pgx/v5/pgxpool"
	"github.com/prometheus/client_golang/prometheus"
)

// RegisterBusinessMetrics exposes bounded-cardinality workflow state for
// operational alerting. It is registered by the single worker process so
// horizontally scaled API instances do not publish duplicate database gauges.
func RegisterBusinessMetrics(pool *pgxpool.Pool) {
	registerStatusCounts(pool, "onboarding_activation_jobs", "Physical device activation jobs by durable status.", "device_activation_job", []string{"NOT_STARTED", "RESERVED", "CONTACT_POSSIBLE", "REGISTERED_OBSERVED", "READY", "RECONCILE_REQUIRED", "BLOCKED"})
	registerStatusCounts(pool, "onboarding_claims", "Physical confirmation claims by status.", "device_binding_claim", []string{"PENDING", "CONFIRMED", "CANCELLED", "EXPIRED"})
	registerStatusCounts(pool, "conversations", "Current conversations by lifecycle status.", "conversation", []string{"PREPARING", "ROOM_ISSUED", "STARTING_AGENT", "ACTIVE", "STOPPING", "COMPLETED", "FAILED", "EXPIRED"})
	registerStatusCounts(pool, "privacy_requests", "Current privacy requests by status.", "privacy_request", []string{"SUBMITTED", "VERIFYING", "EXECUTING", "COMPLETED", "PARTIAL_FAILED"})
	registerStatusCounts(pool, "firmware_rollouts", "Current firmware rollouts by status.", "firmware_rollout", []string{"DRAFT", "RUNNING", "PAUSED", "COMPLETED", "ROLLED_BACK"})
	registerStatusCounts(pool, "firmware_assignments", "Current firmware assignments by status.", "firmware_assignment", []string{"ASSIGNED", "DOWNLOADING", "INSTALLING", "CONFIRMED", "FAILED", "ROLLED_BACK"})
	prometheus.MustRegister(prometheus.NewGaugeFunc(prometheus.GaugeOpts{
		Namespace: "voice_platform",
		Subsystem: "firmware",
		Name:      "stalled_rollouts",
		Help:      "Running firmware rollouts not updated for at least 15 minutes.",
	}, func() float64 {
		return queryCount(pool, "SELECT count(*)::float8 FROM firmware_rollout WHERE status='RUNNING' AND updated_at < now()-interval '15 minutes'")
	}))
	prometheus.MustRegister(prometheus.NewGaugeFunc(prometheus.GaugeOpts{
		Namespace: "voice_platform", Subsystem: "provider", Name: "notification_backlog",
		Help: "Provider callback events pending or failed for more than one minute.",
	}, func() float64 {
		return queryCount(pool, "SELECT count(*)::float8 FROM provider_event WHERE processing_status IN ('pending','failed') AND received_at<now()-interval '1 minute'")
	}))
	for _, window := range []struct {
		label string
		days  int
	}{{"7d", 7}, {"30d", 30}} {
		window := window
		prometheus.MustRegister(prometheus.NewGaugeFunc(prometheus.GaugeOpts{
			Namespace: "voice_platform", Subsystem: "security", Name: "certificates_expiring",
			Help:        "Active managed certificate references expiring in the selected window.",
			ConstLabels: prometheus.Labels{"window": window.label},
		}, func() float64 {
			return queryCount(pool, "SELECT count(*)::float8 FROM ops_resource_reference WHERE resource_type='CERTIFICATE' AND status='ACTIVE' AND expires_at<=now()+$1*interval '1 day'", window.days)
		}))
	}
	for _, category := range []string{"BUSINESS", "TECHNICAL", "SECURITY", "COST"} {
		category := category
		prometheus.MustRegister(prometheus.NewGaugeFunc(prometheus.GaugeOpts{
			Namespace: "voice_platform", Name: "alert_incidents",
			Help:        "Current non-resolved alert incident count by category.",
			ConstLabels: prometheus.Labels{"category": category},
		}, func() float64 {
			return queryCount(pool, "SELECT count(*)::float8 FROM alert_incident WHERE category=$1 AND status<>'RESOLVED'", category)
		}))
	}
}

func registerStatusCounts(pool *pgxpool.Pool, name, help, table string, statuses []string) {
	for _, status := range statuses {
		status := status
		prometheus.MustRegister(prometheus.NewGaugeFunc(prometheus.GaugeOpts{
			Namespace:   "voice_platform",
			Name:        name,
			Help:        help,
			ConstLabels: prometheus.Labels{"status": status},
		}, func() float64 {
			return queryCount(pool, "SELECT count(*)::float8 FROM "+table+" WHERE status=$1", status)
		}))
	}
}

func queryCount(pool *pgxpool.Pool, query string, args ...any) float64 {
	ctx, cancel := context.WithTimeout(context.Background(), time.Second)
	defer cancel()
	var count float64
	if err := pool.QueryRow(ctx, query, args...).Scan(&count); err != nil {
		return 0
	}
	return count
}