package obsx

import (
	"io"
	"net/http"
	"net/http/httptest"
	"strings"
	"testing"
)

func TestMetrics_Counter(t *testing.T) {
	m := NewMetrics(MetricsConfig{Namespace: "test"})
	c := m.Counter("requests_total", "Total requests", "method")
	c.WithLabelValues("GET").Inc()
	c.WithLabelValues("GET").Inc()
	c.WithLabelValues("POST").Inc()

	body := scrape(t, m)
	if !strings.Contains(body, `test_requests_total{method="GET"} 2`) {
		t.Errorf("expected GET counter=2, got:\n%s", body)
	}
	if !strings.Contains(body, `test_requests_total{method="POST"} 1`) {
		t.Errorf("expected POST counter=1, got:\n%s", body)
	}
}

func TestMetrics_Histogram(t *testing.T) {
	m := NewMetrics(MetricsConfig{Namespace: "test"})
	h := m.Histogram("duration_seconds", "Duration", nil, "op")
	h.WithLabelValues("query").Observe(0.1)

	body := scrape(t, m)
	if !strings.Contains(body, "test_duration_seconds") {
		t.Errorf("expected histogram, got:\n%s", body)
	}
}

func TestMetrics_Gauge(t *testing.T) {
	m := NewMetrics(MetricsConfig{Namespace: "test"})
	g := m.Gauge("connections", "Active connections", "pool")
	g.WithLabelValues("main").Set(42)

	body := scrape(t, m)
	if !strings.Contains(body, `test_connections{pool="main"} 42`) {
		t.Errorf("expected gauge=42, got:\n%s", body)
	}
}

func TestMetrics_Handler(t *testing.T) {
	m := NewMetrics(MetricsConfig{})
	handler := m.Handler()
	if handler == nil {
		t.Fatal("Handler returned nil")
	}
}

func scrape(t *testing.T, m *Metrics) string {
	t.Helper()
	w := httptest.NewRecorder()
	r, _ := http.NewRequest("GET", "/metrics", nil)
	m.Handler().ServeHTTP(w, r)
	body, _ := io.ReadAll(w.Body)
	return string(body)
}