You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: repair_pack.go
    path of file: ./repos/restic/internal/repository
    
    the code of the file until where you have to start completion: package repository

import (
	"context"
	"errors"
	"io"

	"github.com/restic/restic/internal/restic"
	"github.com/restic/restic/internal/ui/progress"
	"golang.org/x/sync/errgroup"
)

func RepairPacks(ctx context.Context, repo restic.Repository, ids restic.IDSet, printer progress.Printer) error {
	wg, wgCtx := errgroup.WithContext(ctx)
	repo.StartPackUploader(wgCtx, wg)

	printer.P("salvaging intact data from specified pack files")
	bar := printer.NewCounter("pack files")
	bar.SetMax(uint64(len(ids)))
	defer bar.Done()

	wg.Go(func() error {
		// examine all data the indexes have for the pack file
		for b := range repo.Index().ListPacks(wgCtx, ids) {
			blobs := b.Blobs
			if len(blobs) == 0 {
				printer.E("no blobs found for pack %v", b.PackID)
				bar.Add(1)
				continue
			}

			err := repo.LoadBlobsFromPack(wgCtx, b.PackID, blobs, func(blob restic.BlobHandle, buf []byte, err error) error {
				if err != nil {
					// Fallback path
					buf, err = repo.LoadBlob(wgCtx, blob.Type, blob.ID, nil)
					if err != nil {
						printer.E("failed to load blob %v: %v", blob.ID, er
    
func RepairPacks(ctx context.Context, repo restic.Repository, ids restic.IDSet, printer progress.Printer) error {
	wg, wgCtx := errgroup.WithContext(ctx)
	repo.StartPackUploader(wgCtx, wg)

	printer.P("salvaging intact data from specified pack files")
	bar := printer.NewCounter("pack files")
	bar.SetMax(uint64(len(ids)))
	defer bar.Done()

	wg.Go(func() error {
		// examine all data the indexes have for the pack file
		for b := range repo.Index().ListPacks(wgCtx, ids) {
			blobs := b.Blobs
			if len(blobs) == 0 {
				printer.E("no blobs found for pack %v", b.PackID)
				bar.Add(1)
				continue
			}

			err := repo.LoadBlobsFromPack(wgCtx, b.PackID, blobs, func(blob restic.BlobHandle, buf []byte, err error) error {
				if err != nil {
					// Fallback path
					buf, err = repo.LoadBlob(wgCtx, blob.Type, blob.ID, nil)
					if err != nil {
						printer.E("failed to load blob %v: %v", blob.ID, err)
						return nil
					}
				}
				id, _, _, err := repo.SaveBlob(wgCtx, blob.Type, buf, restic.ID{}, true)
				if !id.Equal(blob.ID) {
					panic("pack id mismatch during upload")
				}
				return err
			})
			// ignore truncated file parts
			if err != nil && !errors.Is(err, io.ErrUnexpectedEOF) {
				return err
			}
			bar.Add(1)
		}
		return repo.Flush(wgCtx)
	})

	err := wg.Wait()
	bar.Done()
	if err != nil {
		return err
	}

	// remove salvaged packs from index
	printer.P("rebuilding index")

	bar = printer.NewCounter("packs processed")
	err = repo.Index().Save(ctx, repo, ids, nil, restic.MasterIndexSaveOpts{
		SaveProgress: bar,
		DeleteProgress: func() *progress.Counter {
			return printer.NewCounter("old indexes deleted")
		},
		DeleteReport: func(id restic.ID, _ error) {
			printer.VV("removed index %v", id.String())
		},
	})

	if err != nil {
		return err
	}

	// cleanup
	printer.P("removing salvaged pack files")
	// if we fail to delete the damaged pack files, then prune will remove them later on
	bar = printer.NewCounter("files deleted")
	_ = restic.ParallelRemove(ctx, repo, ids, restic.PackFile, nil, bar)
	bar.Done()

	return nil
}