package writecachebadger

import (
	"fmt"
	"os"
	"path/filepath"

	"git.frostfs.info/TrueCloudLab/frostfs-node/internal/logs"
	storagelog "git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/internal/log"
	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/writecache"
	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/util"
	cid "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/container/id"
	oid "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/object/id"
	"github.com/dgraph-io/badger/v4"
	"go.uber.org/zap"
)

// store represents persistent storage with in-memory LRU cache
// for flushed items on top of it.
type store struct {
	db *badger.DB
}

type internalKey [len(cid.ID{}) + len(oid.ID{})]byte

func (k internalKey) address() oid.Address {
	var addr oid.Address
	var cnr cid.ID
	var obj oid.ID
	copy(cnr[:], k[:len(cnr)])
	copy(obj[:], k[len(cnr):])
	addr.SetContainer(cnr)
	addr.SetObject(obj)
	return addr
}

func addr2key(addr oid.Address) internalKey {
	var key internalKey
	cnr, obj := addr.Container(), addr.Object()
	copy(key[:len(cnr)], cnr[:])
	copy(key[len(cnr):], obj[:])
	return key
}

const dbName = "small.badger"

func (c *cache) openStore(readOnly bool) error {
	err := util.MkdirAllX(c.path, os.ModePerm)
	if err != nil {
		return err
	}

	c.db, err = OpenDB(filepath.Join(c.path, dbName), readOnly, c.log)
	if err != nil {
		return fmt.Errorf("could not open database: %w", err)
	}

	return nil
}

func (c *cache) deleteFromDB(keys []internalKey) []internalKey {
	if len(keys) == 0 {
		return keys
	}

	wb := c.db.NewWriteBatch()

	var errorIndex int
	for errorIndex = range keys {
		if err := wb.Delete(keys[errorIndex][:]); err != nil {
			break
		}
	}

	for i := 0; i < errorIndex; i++ {
		c.objCounters.DecDB()
		c.metrics.Evict(writecache.StorageTypeDB)
		storagelog.Write(c.log,
			storagelog.AddressField(keys[i]),
			storagelog.StorageTypeField(wcStorageType),
			storagelog.OpField("db DELETE"),
		)
	}

	if err := wb.Flush(); err != nil {
		c.log.Error(logs.WritecacheCantRemoveObjectsFromTheDatabase, zap.Error(err))
	}

	copy(keys, keys[errorIndex:])
	return keys[:len(keys)-errorIndex]
}