package metrics

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

func TestRegistryRendersCountersWithLabels(t *testing.T) {
	registry := NewRegistry()
	registry.AddCounter("vehicle_frames_total", Labels{"protocol": "JT808", "status": "ok"}, 2)
	registry.IncCounter("vehicle_frames_total", Labels{"status": "ok", "protocol": "JT808"})
	registry.IncCounter("vehicle_publish_errors_total", Labels{"target": "kafka"})

	text := registry.Render()

	for _, want := range []string{
		`# TYPE vehicle_frames_total counter`,
		`vehicle_frames_total{protocol="JT808",status="ok"} 3`,
		`# TYPE vehicle_publish_errors_total counter`,
		`vehicle_publish_errors_total{target="kafka"} 1`,
	} {
		if !strings.Contains(text, want) {
			t.Fatalf("metrics missing %s:\n%s", want, text)
		}
	}
}

func TestRegistryRendersGaugesWithLabels(t *testing.T) {
	registry := NewRegistry()
	registry.SetGauge("vehicle_gateway_connections", Labels{"protocol": "JT808"}, 2)
	registry.AddGauge("vehicle_gateway_connections", Labels{"protocol": "JT808"}, -1)
	registry.SetGauge("vehicle_gateway_connections", Labels{"protocol": "GB32960"}, 3)

	text := registry.Render()

	for _, want := range []string{
		`# TYPE vehicle_gateway_connections gauge`,
		`vehicle_gateway_connections{protocol="GB32960"} 3`,
		`vehicle_gateway_connections{protocol="JT808"} 1`,
	} {
		if !strings.Contains(text, want) {
			t.Fatalf("metrics missing %s:\n%s", want, text)
		}
	}
}

func TestHandlerServesPrometheusText(t *testing.T) {
	registry := NewRegistry()
	registry.IncCounter("vehicle_kafka_commits_total", Labels{"service": "history"})
	handler := NewHandler(registry)
	request := httptest.NewRequest(http.MethodGet, "/metrics", nil)
	response := httptest.NewRecorder()

	handler.ServeHTTP(response, request)

	if response.Code != http.StatusOK {
		t.Fatalf("status = %d body=%s", response.Code, response.Body.String())
	}
	if got := response.Header().Get("Content-Type"); !strings.Contains(got, "text/plain") {
		t.Fatalf("content-type = %q", got)
	}
	if !strings.Contains(response.Body.String(), `vehicle_kafka_commits_total{service="history"} 1`) {
		t.Fatalf("body = %s", response.Body.String())
	}
}

func TestHandlerRejectsNonMetricsPath(t *testing.T) {
	handler := NewHandler(NewRegistry())
	request := httptest.NewRequest(http.MethodGet, "/readyz", nil)
	response := httptest.NewRecorder()

	handler.ServeHTTP(response, request)

	if response.Code != http.StatusNotFound {
		t.Fatalf("status = %d", response.Code)
	}
}