package blobtree

import (
	"context"
	"encoding/binary"
	"errors"

	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/blobstor/common"
	apistatus "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/client/status"
	oid "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/object/id"
)

func (b *BlobTree) Exists(_ context.Context, prm common.ExistsPrm) (common.ExistsRes, error) {
	if len(prm.StorageID) == storageIDLength {
		return b.existsFromIdx(prm.Address, binary.LittleEndian.Uint64(prm.StorageID))
	}
	return b.findAndCheck(prm.Address)
}

func (b *BlobTree) existsFromIdx(addr oid.Address, idx uint64) (common.ExistsRes, error) {
	dir := b.getDirectoryPath(addr)
	path := b.getFilePath(dir, idx)

	b.fileLock.RLock(path)
	defer b.fileLock.RUnlock(path)

	records, err := b.readFileContent(path)
	if err != nil {
		return common.ExistsRes{}, err
	}

	for i := range records {
		if records[i].Address.Equals(addr) {
			return common.ExistsRes{
				Exists: true,
			}, nil
		}
	}

	return common.ExistsRes{}, nil
}

func (b *BlobTree) findAndCheck(addr oid.Address) (common.ExistsRes, error) {
	dir := b.getDirectoryPath(addr)
	_, err := b.findFileIdx(dir, addr)
	if err != nil {
		var notFound *apistatus.ObjectNotFound
		if errors.As(err, &notFound) {
			return common.ExistsRes{}, nil
		}
		return common.ExistsRes{}, err
	}
	return common.ExistsRes{Exists: true}, nil
}