package metrics

import (
	"testing"
	"time"

	"github.com/prometheus/client_golang/prometheus"

	outcomeDomain "proxy-pool/internal/domain/outcome"
	proxyDomain "proxy-pool/internal/domain/proxy"
)

func TestGatewayCollectorRecordsOnlyFixedDimensions(t *testing.T) {
	registry := prometheus.NewRegistry()
	collector, err := NewGatewayCollector(registry)
	if err != nil {
		t.Fatalf("NewGatewayCollector() = %v", err)
	}
	collector.Observe(outcomeDomain.Event{Stage: outcomeDomain.StageDial, Success: true})
	collector.Observe(outcomeDomain.Event{Stage: outcomeDomain.StageTunnel, Success: false})
	collector.Observe(outcomeDomain.Event{Stage: outcomeDomain.StageUnspecified, Success: true})
	collector.ObserveDropped()
	collector.ObserveCapacityInvariant(proxyDomain.CapacityInvariant{
		Violation: proxyDomain.CapacityInvariantReleaseFinished,
	})
	collector.ObserveCapacityInvariant(proxyDomain.CapacityInvariant{Violation: "unknown"})
	collector.ObserveRequestStarted("HTTP")
	collector.ObserveRequestStarted("CONNECT")
	collector.ObserveRequestFinished("HTTP")
	collector.ObserveRequestFinished("CONNECT")
	collector.ObserveRequestDuration("HTTP", 25*time.Millisecond)
	collector.ObserveRequestDuration("CONNECT", 2*time.Second)
	collector.ObserveRequestDuration("unknown", time.Second)
	collector.ObserveTunnelOpened()
	collector.ObserveTunnelClosed()
	collector.ObserveRequestStarted("unknown")

	assertMetricValue(t, registry, "proxy_pool_gateway_outcomes_total", map[string]string{
		"stage": "DIAL", "result": "success",
	}, 1)
	assertMetricValue(t, registry, "proxy_pool_gateway_outcomes_total", map[string]string{
		"stage": "TUNNEL", "result": "failure",
	}, 1)
	assertMetricValue(t, registry, "proxy_pool_gateway_outcome_queue_dropped_total", nil, 1)
	assertMetricValue(t, registry, "proxy_pool_gateway_capacity_invariant_violations_total", map[string]string{
		"operation": "release_finished",
	}, 1)
	assertMetricValue(t, registry, "proxy_pool_gateway_requests_total", map[string]string{
		"protocol": "HTTP",
	}, 1)
	assertMetricValue(t, registry, "proxy_pool_gateway_requests_total", map[string]string{
		"protocol": "CONNECT",
	}, 1)
	assertMetricValue(t, registry, "proxy_pool_gateway_requests_in_flight", map[string]string{
		"protocol": "HTTP",
	}, 0)
	assertMetricValue(t, registry, "proxy_pool_gateway_requests_in_flight", map[string]string{
		"protocol": "CONNECT",
	}, 0)
	assertMetricValue(t, registry, "proxy_pool_gateway_active_tunnels", nil, 0)
	assertHistogramSampleCount(t, registry, "proxy_pool_gateway_request_duration_seconds", map[string]string{"protocol": "HTTP"}, 1)
	assertHistogramSampleCount(t, registry, "proxy_pool_gateway_request_duration_seconds", map[string]string{"protocol": "CONNECT"}, 1)
}

func TestNewGatewayCollectorReusesRegisteredCollectors(t *testing.T) {
	registry := prometheus.NewRegistry()
	first, err := NewGatewayCollector(registry)
	if err != nil {
		t.Fatalf("first NewGatewayCollector() = %v", err)
	}
	second, err := NewGatewayCollector(registry)
	if err != nil {
		t.Fatalf("second NewGatewayCollector() = %v", err)
	}
	first.ObserveDropped()
	second.ObserveDropped()
	assertMetricValue(t, registry, "proxy_pool_gateway_outcome_queue_dropped_total", nil, 2)
}

func assertHistogramSampleCount(t *testing.T, registry *prometheus.Registry, name string, labels map[string]string, want uint64) {
	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.GetHistogram().GetSampleCount() == want {
				return
			}
		}
	}
	t.Fatalf("histogram %s labels=%v count=%d was not found", name, labels, want)
}