package cache

import (
	"context"
	"encoding/gob"
	"os"
	"path/filepath"
	"time"

	"git.belvedersky.ru/common/logger"
	"git.belvedersky.ru/common/logger/service"

	badger "github.com/dgraph-io/badger/v3"
)

type CacheConfig struct {
	Dir string
}

type CacheRepository struct {
	cache  *badger.DB
	logger *service.LoggerService
	config *CacheConfig
	Err    service.TypeError
}

// Новый сервис кеша
func New(config *CacheConfig, l *logger.Logger) (repo *CacheRepository, err error) {
	path := filepath.Join(".", config.Dir)
	if _, err = os.Stat(path); os.IsNotExist(err) {
		err := os.Mkdir(path, 0777)
		if err != nil {
			return nil, err
		}
	}
	cacheConfig := badger.DefaultOptions(config.Dir)
	log := l.Create("cache")
	cacheConfig.Logger = log

	cache, err := badger.Open(cacheConfig.WithLoggingLevel(badger.ERROR))
	if err != nil {
		return nil, err
	}
	r := CacheRepository{
		config: config,
		cache:  cache,
		Err:    service.TypeError{Code: 3, Description: "Ошибка badger"},
		logger: (*service.LoggerService)(log),
	}
	return &r, nil
}

// Регистрация структур в кеше
func (c *CacheRepository) RegisterStruct(value interface{}) {
	gob.Register(value)
}

func (k *CacheRepository) RunGC(ctx context.Context, interval time.Duration, discardRatio float64) {
	go func() {
		ticker := time.NewTicker(interval)
		defer ticker.Stop()

		for {
			select {
			case <-ticker.C:
				start := time.Now()

				for {
					err := k.cache.RunValueLogGC(discardRatio)
					if err != nil {
						if err == badger.ErrNoRewrite {
							break
						}
						k.logger.Error(service.LogErrorStruct{Message: "garbage collection failed: " + err.Error()})
						break
					}
				}

				k.logger.Log.Printf("garbage collection finished %v\n", time.Since(start))
			case <-ctx.Done():
				return
			}
		}
	}()
}