package blobtree

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

	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/blobstor/common"
	"git.frostfs.info/TrueCloudLab/frostfs-observability/tracing"
	"go.opentelemetry.io/otel/attribute"
	"go.opentelemetry.io/otel/trace"
)

func (b *BlobTree) Iterate(ctx 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)
	}()

	_, span := tracing.StartSpanFromContext(ctx, "BlobTree.Iterate",
		trace.WithAttributes(
			attribute.String("path", b.cfg.rootPath),
			attribute.Bool("ignore_errors", prm.IgnoreErrors),
		))
	defer span.End()

	err = b.iterateDir("", prm)
	return common.IterateRes{}, err
}

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

	for _, entity := range entities {
		if entity.IsDir() {
			err := b.iterateDir(filepath.Join(dir, entity.Name()), prm)
			if err != nil {
				return err
			}
			continue
		}

		if b.isTempFile(entity.Name()) {
			continue
		}

		path := filepath.Join(dir, entity.Name())
		err = b.iterateRecords(path, prm)
		if err != nil {
			return err
		}
	}
	return nil
}

func (b *BlobTree) iterateRecords(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
		}

		err = prm.Handler(common.IterationElement{
			Address:    record.Address,
			ObjectData: record.Data,
			StorageID:  pathToStorageID(path),
		})
		if err != nil {
			return err
		}
	}
	return nil
}