package metrics

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

func TestHandlerUsesOnlyFixedLowCardinalityLabels(t *testing.T) {
	t.Parallel()
	registry := New("ins_test-1", "v-test")
	registry.ObserveReconcileRun(nil, 1500*time.Millisecond)
	registry.ObserveReconcileItem("success")
	registry.ObserveReconcileItem("lease_lost")
	registry.SetConvergence(16, 2)
	registry.ObserveOrphanScan(20, 1, 3, nil)
	registry.ObserveOrphanCleanupBlocked("ratio_exceeded")
	registry.ObserveOrphanCleanup(1, 1)

	request := httptest.NewRequest("GET", "/metrics", nil)
	response := httptest.NewRecorder()
	registry.Handler().ServeHTTP(response, request)
	body := response.Body.String()
	for _, expected := range []string{
		`sense_build_info{instance_id="ins_test-1",version="v-test"} 1`,
		`sense_reconcile_items_total{result="lease_lost"} 1`,
		`sense_reconcile_devices{state="unconverged"} 2`,
		`sense_orphan_paths{classification="owned_stale"} 1`,
		`sense_orphan_cleanup_blocked_total{reason="ratio_exceeded"} 1`,
	} {
		if !strings.Contains(body, expected) {
			t.Fatalf("metrics output lacks %q:\n%s", expected, body)
		}
	}
	for _, forbidden := range []string{
		"tenant_id", "site_id", "device_id", "path_name", "rtsp://", "credential",
	} {
		if strings.Contains(body, forbidden) {
			t.Fatalf("high-cardinality or secret-bearing label appeared: %q", forbidden)
		}
	}
	if response.Header().Get("Cache-Control") != "no-store" {
		t.Fatal("metrics responses must not be cached")
	}
}

func TestRegistryIsSafeForConcurrentObservers(t *testing.T) {
	t.Parallel()
	registry := New("ins_concurrent", "dev")
	var wait sync.WaitGroup
	for index := 0; index < 32; index++ {
		wait.Add(1)
		go func() {
			defer wait.Done()
			for count := 0; count < 100; count++ {
				registry.ObserveReconcileItem("success")
				registry.SetConvergence(128, count%17)
			}
		}()
	}
	wait.Wait()
	response := httptest.NewRecorder()
	registry.Handler().ServeHTTP(response, httptest.NewRequest("GET", "/metrics", nil))
	if !strings.Contains(response.Body.String(), `sense_reconcile_items_total{result="success"} 3200`) {
		t.Fatalf("concurrent counter lost updates: %s", response.Body.String())
	}
}

func TestGenerateInstanceIDShape(t *testing.T) {
	t.Parallel()
	first, err := GenerateInstanceID()
	if err != nil {
		t.Fatal(err)
	}
	second, err := GenerateInstanceID()
	if err != nil {
		t.Fatal(err)
	}
	if len(first) != 28 || !strings.HasPrefix(first, "ins_") || first == second {
		t.Fatalf("unexpected instance identifiers: %q %q", first, second)
	}
}