package imageproxy

import (
	"errors"
	"testing"

	"github.com/prometheus/client_golang/prometheus"
	"github.com/prometheus/client_golang/prometheus/testutil"
	"sneak.berlin/go/pixa/internal/imgcache"
)

// TestNew_RegistersItsCountersOnItsRegistry checks that New registers the
// proxy's counters on the registry it is given, under the names README.md
// gives them. The cache registers its own counters on another registry.
func TestNew_RegistersItsCountersOnItsRegistry(t *testing.T) {
	t.Parallel()

	cache, err := imgcache.NewCache(setupTestDB(t),
		imgcache.Config{StateDir: t.TempDir(), MaxBytes: 1 << 30},
		prometheus.NewRegistry())
	if err != nil {
		t.Fatalf("imgcache.NewCache() error = %v", err)
	}

	registry := prometheus.NewRegistry()

	_, err = New(&Config{Cache: cache}, registry)
	if err != nil {
		t.Fatalf("New() error = %v", err)
	}

	names := []string{
		"pixa_upstream_fetches_total",
		"pixa_upstream_fetch_bytes_total",
		"pixa_transforms_total",
	}

	count, err := testutil.GatherAndCount(registry, names...)
	if err != nil {
		t.Fatalf("testutil.GatherAndCount() error = %v", err)
	}

	if count != len(names) {
		t.Errorf("%d of the counters %v are on the registry, want %d",
			count, names, len(names))
	}
}

// TestNew_FailsWhenItsCountersCannotBeRegistered makes a second proxy on
// the registry of a first. Its counters have the same names, so the
// registry refuses them, and New must return that error.
func TestNew_FailsWhenItsCountersCannotBeRegistered(t *testing.T) {
	t.Parallel()

	cache, err := imgcache.NewCache(setupTestDB(t),
		imgcache.Config{StateDir: t.TempDir(), MaxBytes: 1 << 30},
		prometheus.NewRegistry())
	if err != nil {
		t.Fatalf("imgcache.NewCache() error = %v", err)
	}

	registry := prometheus.NewRegistry()

	_, err = New(&Config{Cache: cache}, registry)
	if err != nil {
		t.Fatalf("New() of the first proxy error = %v", err)
	}

	_, err = New(&Config{Cache: cache}, registry)
	t.Logf("New() of the second proxy error = %v", err)

	var alreadyRegistered prometheus.AlreadyRegisteredError
	if !errors.As(err, &alreadyRegistered) {
		t.Errorf("New() of the second proxy error = %v, want %T",
			err, alreadyRegistered)
	}
}