package blobtree

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

	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/blobstor/common"
)

func (b *BlobTree) Iterate(_ context.Context, prm common.IteratePrm) (common.IterateRes, error) {
	var (
		startedAt = time.Now()
		err       error
	)
	defer func() {
		b.cfg.metrics.Iterate(time.Since(startedAt), err == nil)
	}()

	err = b.iterateDir(b.cfg.rootPath, 0, prm)
	return common.IterateRes{}, err
}

func (b *BlobTree) iterateDir(dir string, depth uint64, prm common.IteratePrm) error {
	entities, err := os.ReadDir(dir)
	if err != nil {
		if prm.IgnoreErrors {
			return nil
		}
		return err
	}

	for _, entity := range entities {
		if depth < b.cfg.depth && entity.IsDir() {
			err := b.iterateDir(filepath.Join(dir, entity.Name()), depth+1, prm)
			if err != nil {
				return err
			}
		}
		if depth != b.cfg.depth {
			continue
		}
		if b.isTempFile(entity.Name()) {
			continue
		}
		idx, err := b.parseIdx(entity.Name())
		if err != nil {
			continue
		}
		path := b.getFilePath(dir, idx)
		err = b.iterateRecords(idx, path, prm)
		if err != nil {
			return err
		}
	}
	return nil
}

func (b *BlobTree) iterateRecords(idx uint64, path string, prm common.IteratePrm) error {
	b.fileLock.RLock(path)
	defer b.fileLock.RUnlock(path)

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

	for _, record := range records {
		if prm.LazyHandler != nil {
			if err = prm.LazyHandler(record.Address, func() ([]byte, error) {
				return record.Data, nil
			}); err != nil {
				return err
			}
			continue
		}

		record.Data, err = b.compressor.Decompress(record.Data)
		if err != nil {
			if prm.IgnoreErrors {
				if prm.ErrorHandler != nil {
					return prm.ErrorHandler(record.Address, err)
				}
				continue
			}
			return err
		}

		storageID := make([]byte, storageIDLength)
		binary.LittleEndian.PutUint64(storageID, idx)
		err = prm.Handler(common.IterationElement{
			Address:    record.Address,
			ObjectData: record.Data,
			StorageID:  storageID,
		})
		if err != nil {
			return err
		}
	}
	return nil
}