package metrics

import (
	"testing"

	"github.com/prometheus/client_golang/prometheus"
	dto "github.com/prometheus/client_model/go"

	healthDomain "proxy-pool/internal/domain/health"
)

func TestCheckerCollectorRecordsOnlyFixedDimensions(t *testing.T) {
	registry := prometheus.NewRegistry()
	collector, err := NewCheckerCollector(registry)
	if err != nil {
		t.Fatalf("NewCheckerCollector() = %v", err)
	}
	collector.ObserveTaskDispatch(healthDomain.LevelBasic, 2)
	collector.ObserveTaskDispatch(healthDomain.LevelTarget, 1)
	collector.ObserveTaskDispatch("invalid", 99)
	collector.ObserveObservation(healthDomain.LevelBasic, healthDomain.ObservationMetricAccepted)
	collector.ObserveObservation(healthDomain.LevelTarget, healthDomain.ObservationMetricRejected)
	collector.ObserveObservation("invalid", healthDomain.ObservationMetricAccepted)

	assertMetricValue(t, registry, "proxy_pool_checker_tasks_dispatched_total", map[string]string{"level": "BASIC"}, 2)
	assertMetricValue(t, registry, "proxy_pool_checker_tasks_dispatched_total", map[string]string{"level": "TARGET"}, 1)
	assertMetricValue(t, registry, "proxy_pool_checker_observations_total", map[string]string{
		"level": "BASIC", "result": "accepted",
	}, 1)
	assertMetricValue(t, registry, "proxy_pool_checker_observations_total", map[string]string{
		"level": "TARGET", "result": "rejected",
	}, 1)
}

func TestNewCheckerCollectorReusesRegisteredCollectors(t *testing.T) {
	registry := prometheus.NewRegistry()
	first, err := NewCheckerCollector(registry)
	if err != nil {
		t.Fatalf("first NewCheckerCollector() = %v", err)
	}
	second, err := NewCheckerCollector(registry)
	if err != nil {
		t.Fatalf("second NewCheckerCollector() = %v", err)
	}
	first.ObserveTaskDispatch(healthDomain.LevelEgress, 1)
	second.ObserveTaskDispatch(healthDomain.LevelEgress, 1)
	assertMetricValue(t, registry, "proxy_pool_checker_tasks_dispatched_total", map[string]string{"level": "EGRESS"}, 2)
}

func assertMetricValue(t *testing.T, registry *prometheus.Registry, name string, labels map[string]string, want float64) {
	t.Helper()
	metrics, err := registry.Gather()
	if err != nil {
		t.Fatalf("Gather() = %v", err)
	}
	for _, family := range metrics {
		if family.GetName() != name {
			continue
		}
		for _, metric := range family.GetMetric() {
			if metricLabelsMatch(metric.GetLabel(), labels) && metric.GetCounter().GetValue() == want {
				return
			}
		}
	}
	t.Fatalf("metric %s labels=%v value=%v was not found", name, labels, want)
}

func metricLabelsMatch(labels []*dto.LabelPair, want map[string]string) bool {
	if len(labels) != len(want) {
		return false
	}
	for _, label := range labels {
		if want[label.GetName()] != label.GetValue() {
			return false
		}
	}
	return true
}