package cache

import (
	"context"
	"testing"
	"time"

	"golang.org/x/sync/singleflight"
)

func TestLoadJSONWithEmptyCachesEmptyAndRecordsMetrics(t *testing.T) {
	ResetMetricsForTest()
	ctx := context.Background()
	c := NewWithOptions("memory", nil, Options{
		Namespace:      "test",
		JitterRatio:    0,
		MetricsEnabled: true,
	})
	var group singleflight.Group
	loads := 0

	value, found, err := LoadJSONWithEmpty(ctx, c, &group, "empty", time.Minute, time.Minute, func(context.Context) (string, bool, error) {
		loads++
		return "", false, nil
	})
	if err != nil {
		t.Fatalf("LoadJSONWithEmpty() error = %v", err)
	}
	if found || value != "" {
		t.Fatalf("first load value=%q found=%v, want empty not found", value, found)
	}

	value, found, err = LoadJSONWithEmpty(ctx, c, &group, "empty", time.Minute, time.Minute, func(context.Context) (string, bool, error) {
		loads++
		return "unexpected", true, nil
	})
	if err != nil {
		t.Fatalf("LoadJSONWithEmpty() cached error = %v", err)
	}
	if found || value != "" {
		t.Fatalf("cached value=%q found=%v, want empty not found", value, found)
	}
	if loads != 1 {
		t.Fatalf("loader calls = %d, want 1", loads)
	}

	snapshot := MetricsSnapshotValue()
	if metricCount(snapshot, "readthrough_empty", "hit") != 1 {
		t.Fatalf("readthrough_empty hit metric missing in %#v", snapshot.Operations)
	}
	if metricCount(snapshot, "readthrough_load", "ok") != 1 {
		t.Fatalf("readthrough_load ok metric missing in %#v", snapshot.Operations)
	}
}

func metricCount(snapshot MetricsSnapshot, operation, result string) int64 {
	for _, item := range snapshot.Operations {
		if item.Operation == operation && item.Result == result {
			return item.Count
		}
	}
	return 0
}