func (store *TagStore) Set(repoName, tag, imageName string, force bool) error {
	img, err := store.LookupImage(imageName)
	store.Lock()
	defer store.Unlock()
	if err != nil {
		return err
	}
	if tag == "" {
		tag = DEFAULTTAG
	}
	if err := validateRepoName(repoName); err != nil {
		return err
	}
	if err := ValidateTagName(tag); err != nil {
		return err
	}
	if err := store.reload(); err != nil {
		return err
	}
	var repo Repository
	repoName = registry.NormalizeLocalName(repoName)
	if r, exists := store.Repositories[repoName]; exists {
		repo = r
		if old, exists := store.Repositories[repoName][tag]; exists && !force {
			return fmt.Errorf("Conflict: Tag %s is already set to image %s, if you want to replace it, please use -f option", tag, old)
		}
	} else {
		repo = make(map[string]string)
		store.Repositories[repoName] = repo
	}
	repo[tag] = img.ID
	return store.save()
}

// SetDigest creates a digest reference to an image ID.
func (store *TagStore) SetDigest(repoName, digest, imageName string) error {
	img, err := store.LookupImage(imageName)
	if err != nil {
		return err
	}

	if err := validateRepoName(repoName); err != nil {
		return err
	}

	if err := validateDigest(digest); err != nil {
		return err
	}

	store.Lock()
	defer store.Unlock()
	if err := store.reload(); err != nil {
		return err
	}

	repoName = registry.NormalizeLocalName(repoName)
	repoRefs, exists := store.Repositories[repoName]
	if !exists {
		repoRefs = Repository{}
		store.Repositories[repoName] = repoRefs
	} else if oldID, exists := repoRefs[digest]; exists && oldID != img.ID {
		return fmt.Errorf("Conflict: Digest %s is already set to image %s", digest, oldID)
	}

	repoRefs[digest] = img.ID
	return store.save()
}

func (store *TagStore) Delete(repoName, tag string) (bool, error) {
	store.Lock()
	defer store.Unlock()
	deleted := false
	if err := store.reload(); err != nil {
		return false, err
	}
	repoName = registry.NormalizeLocalName(repoName)
	if r, exists := store.Repositories[repoName]; exists {
		if tag != "" {
			if _, exists2 := r[tag]; exists2 {
				delete(r, tag)
				if len(r) == 0 {
					delete(store.Repositories, repoName)
				}
				deleted = true
			} else {
				return false, fmt.Errorf("No such tag: %s:%s", repoName, tag)
			}
		} else {
			delete(store.Repositories, repoName)
			deleted = true
		}
	} else {
		return false, fmt.Errorf("No such repository: %s", repoName)
	}
	return deleted, store.save()
}

func (store *TagStore) Delete(repoName, ref string) (bool, error) {
	store.Lock()
	defer store.Unlock()
	deleted := false
	if err := store.reload(); err != nil {
		return false, err
	}

	repoName = registry.NormalizeLocalName(repoName)

	if ref == "" {
		// Delete the whole repository.
		delete(store.Repositories, repoName)
		return true, store.save()
	}

	repoRefs, exists := store.Repositories[repoName]
	if !exists {
		return false, fmt.Errorf("No such repository: %s", repoName)
	}

	if _, exists := repoRefs[ref]; exists {
		delete(repoRefs, ref)
		if len(repoRefs) == 0 {
			delete(store.Repositories, repoName)
		}
		deleted = true
	}

	return deleted, store.save()
}

func (store *TagStore) Get(repoName string) (Repository, error) {
	store.Lock()
	defer store.Unlock()
	if err := store.reload(); err != nil {
		return nil, err
	}
	repoName = registry.NormalizeLocalName(repoName)
	if r, exists := store.Repositories[repoName]; exists {
		return r, nil
	}
	return nil, nil
}

func (store *TagStore) SetLoad(repoName, tag, imageName string, force bool, out io.Writer) error {
	img, err := store.LookupImage(imageName)
	store.Lock()
	defer store.Unlock()
	if err != nil {
		return err
	}
	if tag == "" {
		tag = tags.DEFAULTTAG
	}
	if err := validateRepoName(repoName); err != nil {
		return err
	}
	if err := tags.ValidateTagName(tag); err != nil {
		if _, formatError := err.(tags.ErrTagInvalidFormat); !formatError {
			return err
		}
		if _, dErr := digest.ParseDigest(tag); dErr != nil {
			// Still return the tag validation error.
			// It's more likely to be a user generated issue.
			return err
		}
	}
	if err := store.reload(); err != nil {
		return err
	}
	var repo Repository
	repoName = registry.NormalizeLocalName(repoName)
	if r, exists := store.Repositories[repoName]; exists {
		repo = r
		if old, exists := store.Repositories[repoName][tag]; exists {

			if !force {
				return fmt.Errorf("Conflict: Tag %s is already set to image %s, if you want to replace it, please use -f option", tag, old)
			}

			if old != img.ID && out != nil {

				fmt.Fprintf(out, "The image %s:%s already exists, renaming the old one with ID %s to empty string\n", repoName, tag, old[:12])

			}
		}
	} else {
		repo = make(map[string]string)
		store.Repositories[repoName] = repo
	}
	repo[tag] = img.ID
	return store.save()
}

// GetID returns ID for image name.
func (store *TagStore) GetID(name string) (string, error) {
	repoName, ref := parsers.ParseRepositoryTag(name)
	if ref == "" {
		ref = tags.DefaultTag
	}
	store.Lock()
	defer store.Unlock()
	repoName = registry.NormalizeLocalName(repoName)
	repo, ok := store.Repositories[repoName]
	if !ok {
		return "", ErrNameIsNotExist
	}
	id, ok := repo[ref]
	if !ok {
		return "", ErrNameIsNotExist
	}
	return id, nil
}

// setLoad stores the image to the store.
// If the imageName is already in the repo then a '-f' flag should be used to replace existing image.
func (store *TagStore) setLoad(repoName, tag, imageName string, force bool, out io.Writer) error {
	img, err := store.LookupImage(imageName)
	store.Lock()
	defer store.Unlock()
	if err != nil {
		return err
	}
	if tag == "" {
		tag = tags.DefaultTag
	}
	if err := validateRepoName(repoName); err != nil {
		return err
	}
	if err := tags.ValidateTagName(tag); err != nil {
		return err
	}
	if err := store.reload(); err != nil {
		return err
	}
	var repo Repository
	repoName = registry.NormalizeLocalName(repoName)
	if r, exists := store.Repositories[repoName]; exists {
		repo = r
		if old, exists := store.Repositories[repoName][tag]; exists {

			if !force {
				return fmt.Errorf("Conflict: Tag %s:%s is already set to image %s, if you want to replace it, please use -f option", repoName, tag, old[:12])
			}

			if old != img.ID && out != nil {

				fmt.Fprintf(out, "The image %s:%s already exists, renaming the old one with ID %s to empty string\n", repoName, tag, old[:12])

			}
		}
	} else {
		repo = make(map[string]string)
		store.Repositories[repoName] = repo
	}
	repo[tag] = img.ID
	return store.save()
}

// ImageExport exports list of images to a output stream specified in the
// config. The exported images are archived into a tar when written to the
// output stream. All images with the given tag and all versions containing the
// same tag are exported. names is the set of tags to export, and outStream
// is the writer which the images are written to.
func (s *TagStore) ImageExport(names []string, outStream io.Writer) error {
	// get image json
	tempdir, err := ioutil.TempDir("", "docker-export-")
	if err != nil {
		return err
	}
	defer os.RemoveAll(tempdir)

	rootRepoMap := map[string]repository{}
	addKey := func(name string, tag string, id string) {
		logrus.Debugf("add key [%s:%s]", name, tag)
		if repo, ok := rootRepoMap[name]; !ok {
			rootRepoMap[name] = repository{tag: id}
		} else {
			repo[tag] = id
		}
	}
	for _, name := range names {
		name = registry.NormalizeLocalName(name)
		logrus.Debugf("Serializing %s", name)
		rootRepo := s.Repositories[name]
		if rootRepo != nil {
			// this is a base repo name, like 'busybox'
			for tag, id := range rootRepo {
				addKey(name, tag, id)
				if err := s.exportImage(id, tempdir); err != nil {
					return err
				}
			}
		} else {
			img, err := s.LookupImage(name)
			if err != nil {
				return err
			}

			if img != nil {
				// This is a named image like 'busybox:latest'
				repoName, repoTag := parsers.ParseRepositoryTag(name)

				// Skip digests on save
				if _, err := digest.ParseDigest(repoTag); err == nil {
					repoTag = ""
				}

				// check this length, because a lookup of a truncated has will not have a tag
				// and will not need to be added to this map
				if len(repoTag) > 0 {
					addKey(repoName, repoTag, img.ID)
				}
				if err := s.exportImage(img.ID, tempdir); err != nil {
					return err
				}

			} else {
				// this must be an ID that didn't get looked up just right?
				if err := s.exportImage(name, tempdir); err != nil {
					return err
				}
			}
		}
		logrus.Debugf("End Serializing %s", name)
	}
	// write repositories, if there is something to write
	if len(rootRepoMap) > 0 {
		f, err := os.OpenFile(filepath.Join(tempdir, "repositories"), os.O_RDWR|os.O_CREATE|os.O_TRUNC, 0644)
		if err != nil {
			f.Close()
			return err
		}
		if err := json.NewEncoder(f).Encode(rootRepoMap); err != nil {
			return err
		}
		if err := f.Close(); err != nil {
			return err
		}
		if err := os.Chtimes(filepath.Join(tempdir, "repositories"), time.Unix(0, 0), time.Unix(0, 0)); err != nil {
			return err
		}
	} else {
		logrus.Debugf("There were no repositories to write")
	}

	fs, err := archive.Tar(tempdir, archive.Uncompressed)
	if err != nil {
		return err
	}
	defer fs.Close()

	if _, err := io.Copy(outStream, fs); err != nil {
		return err
	}
	logrus.Debugf("End export image")
	return nil
}

// CmdImageExport exports all images with the given tag. All versions
// containing the same tag are exported. The resulting output is an
// uncompressed tar ball.
// name is the set of tags to export.
// out is the writer where the images are written to.
func (s *TagStore) CmdImageExport(job *engine.Job) engine.Status {
	if len(job.Args) < 1 {
		return job.Errorf("Usage: %s IMAGE [IMAGE...]\n", job.Name)
	}
	// get image json
	tempdir, err := ioutil.TempDir("", "docker-export-")
	if err != nil {
		return job.Error(err)
	}
	defer os.RemoveAll(tempdir)

	rootRepoMap := map[string]Repository{}
	addKey := func(name string, tag string, id string) {
		log.Debugf("add key [%s:%s]", name, tag)
		if repo, ok := rootRepoMap[name]; !ok {
			rootRepoMap[name] = Repository{tag: id}
		} else {
			repo[tag] = id
		}
	}
	for _, name := range job.Args {
		name = registry.NormalizeLocalName(name)
		log.Debugf("Serializing %s", name)
		rootRepo := s.Repositories[name]
		if rootRepo != nil {
			// this is a base repo name, like 'busybox'
			for tag, id := range rootRepo {
				addKey(name, tag, id)
				if err := s.exportImage(job.Eng, id, tempdir); err != nil {
					return job.Error(err)
				}
			}
		} else {
			img, err := s.LookupImage(name)
			if err != nil {
				return job.Error(err)
			}

			if img != nil {
				// This is a named image like 'busybox:latest'
				repoName, repoTag := parsers.ParseRepositoryTag(name)

				// check this length, because a lookup of a truncated has will not have a tag
				// and will not need to be added to this map
				if len(repoTag) > 0 {
					addKey(repoName, repoTag, img.ID)
				}
				if err := s.exportImage(job.Eng, img.ID, tempdir); err != nil {
					return job.Error(err)
				}

			} else {
				// this must be an ID that didn't get looked up just right?
				if err := s.exportImage(job.Eng, name, tempdir); err != nil {
					return job.Error(err)
				}
			}
		}
		log.Debugf("End Serializing %s", name)
	}
	// write repositories, if there is something to write
	if len(rootRepoMap) > 0 {
		rootRepoJson, _ := json.Marshal(rootRepoMap)
		if err := ioutil.WriteFile(path.Join(tempdir, "repositories"), rootRepoJson, os.FileMode(0644)); err != nil {
			return job.Error(err)
		}
	} else {
		log.Debugf("There were no repositories to write")
	}

	fs, err := archive.Tar(tempdir, archive.Uncompressed)
	if err != nil {
		return job.Error(err)
	}
	defer fs.Close()

	if _, err := io.Copy(job.Stdout, fs); err != nil {
		return job.Error(err)
	}
	log.Debugf("End export job: %s", job.Name)
	return engine.StatusOK
}