// Set associates an image with a V1 ID.
func (idserv *V1IDService) Set(v1ID, registry string, id layer.DiffID) error {
	if idserv.store == nil {
		return nil
	}
	if err := v1.ValidateID(v1ID); err != nil {
		return err
	}
	return idserv.store.Set(idserv.namespace(), registry+","+v1ID, []byte(id))
}

// ParseIDOrReference parses string for an image ID or a reference. ID can be
// without a default prefix.
func ParseIDOrReference(idOrRef string) (digest.Digest, Named, error) {
	if err := v1.ValidateID(idOrRef); err == nil {
		idOrRef = "sha256:" + idOrRef
	}
	if dgst, err := digest.ParseDigest(idOrRef); err == nil {
		return dgst, nil, nil
	}
	ref, err := ParseNamed(idOrRef)
	return "", ref, err
}

func validateRemoteName(remoteName reference.Named) error {
	remoteNameStr := remoteName.Name()
	if !strings.Contains(remoteNameStr, "/") {
		// the repository name must not be a valid image ID
		if err := v1.ValidateID(remoteNameStr); err == nil {
			return fmt.Errorf("Invalid repository name (%s), cannot specify 64-byte hexadecimal strings", remoteName)
		}
	}
	return nil
}

// Get finds a layer by its V1 ID.
func (idserv *V1IDService) Get(v1ID, registry string) (layer.ChainID, error) {
	if err := v1.ValidateID(v1ID); err != nil {
		return layer.ChainID(""), err
	}

	idBytes, err := idserv.store.Get(idserv.namespace(), registry+","+v1ID)
	if err != nil {
		return layer.ChainID(""), err
	}
	return layer.ChainID(idBytes), nil
}

func (p *v1Puller) downloadImage(ctx context.Context, repoData *registry.RepositoryData, img *registry.ImgData, layersDownloaded *bool) error {
	if img.Tag == "" {
		logrus.Debugf("Image (id: %s) present in this repository but untagged, skipping", img.ID)
		return nil
	}

	localNameRef, err := reference.WithTag(p.repoInfo.LocalName, img.Tag)
	if err != nil {
		retErr := fmt.Errorf("Image (id: %s) has invalid tag: %s", img.ID, img.Tag)
		logrus.Debug(retErr.Error())
		return retErr
	}

	if err := v1.ValidateID(img.ID); err != nil {
		return err
	}

	progress.Updatef(p.config.ProgressOutput, stringid.TruncateID(img.ID), "Pulling image (%s) from %s", img.Tag, p.repoInfo.CanonicalName.Name())
	success := false
	var lastErr error
	for _, ep := range p.repoInfo.Index.Mirrors {
		ep += "v1/"
		progress.Updatef(p.config.ProgressOutput, stringid.TruncateID(img.ID), fmt.Sprintf("Pulling image (%s) from %s, mirror: %s", img.Tag, p.repoInfo.CanonicalName.Name(), ep))
		if err = p.pullImage(ctx, img.ID, ep, localNameRef, layersDownloaded); err != nil {
			// Don't report errors when pulling from mirrors.
			logrus.Debugf("Error pulling image (%s) from %s, mirror: %s, %s", img.Tag, p.repoInfo.CanonicalName.Name(), ep, err)
			continue
		}
		success = true
		break
	}
	if !success {
		for _, ep := range repoData.Endpoints {
			progress.Updatef(p.config.ProgressOutput, stringid.TruncateID(img.ID), "Pulling image (%s) from %s, endpoint: %s", img.Tag, p.repoInfo.CanonicalName.Name(), ep)
			if err = p.pullImage(ctx, img.ID, ep, localNameRef, layersDownloaded); err != nil {
				// It's not ideal that only the last error is returned, it would be better to concatenate the errors.
				// As the error is also given to the output stream the user will see the error.
				lastErr = err
				progress.Updatef(p.config.ProgressOutput, stringid.TruncateID(img.ID), "Error pulling image (%s) from %s, endpoint: %s, %s", img.Tag, p.repoInfo.CanonicalName.Name(), ep, err)
				continue
			}
			success = true
			break
		}
	}
	if !success {
		err := fmt.Errorf("Error pulling image (%s) from %s, %v", img.Tag, p.repoInfo.CanonicalName.Name(), lastErr)
		progress.Update(p.config.ProgressOutput, stringid.TruncateID(img.ID), err.Error())
		return err
	}
	progress.Update(p.config.ProgressOutput, stringid.TruncateID(img.ID), "Download complete")
	return nil
}

func migrateImages(root string, ls graphIDRegistrar, is image.Store, ms metadata.Store, mappings map[string]image.ID) error {
	graphDir := filepath.Join(root, graphDirName)
	if _, err := os.Lstat(graphDir); err != nil {
		if os.IsNotExist(err) {
			return nil
		}
		return err
	}

	mfile := filepath.Join(root, migrationFileName)
	f, err := os.Open(mfile)
	if err != nil && !os.IsNotExist(err) {
		return err
	} else if err == nil {
		err := json.NewDecoder(f).Decode(&mappings)
		if err != nil {
			f.Close()
			return err
		}
		f.Close()
	}

	dir, err := ioutil.ReadDir(graphDir)
	if err != nil {
		return err
	}
	for _, v := range dir {
		v1ID := v.Name()
		if err := imagev1.ValidateID(v1ID); err != nil {
			continue
		}
		if _, exists := mappings[v1ID]; exists {
			continue
		}
		if err := migrateImage(v1ID, root, ls, is, ms, mappings); err != nil {
			continue
		}
	}

	f, err = os.OpenFile(mfile, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0600)
	if err != nil {
		return err
	}
	defer f.Close()
	if err := json.NewEncoder(f).Encode(mappings); err != nil {
		return err
	}

	return nil
}

// Get finds a layer by its V1 ID.
func (idserv *V1IDService) Get(v1ID, registry string) (layer.DiffID, error) {
	if idserv.store == nil {
		return "", errors.New("no v1IDService storage")
	}
	if err := v1.ValidateID(v1ID); err != nil {
		return layer.DiffID(""), err
	}

	idBytes, err := idserv.store.Get(idserv.namespace(), registry+","+v1ID)
	if err != nil {
		return layer.DiffID(""), err
	}
	return layer.DiffID(idBytes), nil
}

// fixManifestLayers removes repeated layers from the manifest and checks the
// correctness of the parent chain.
func fixManifestLayers(m *schema1.Manifest) error {
	imgs := make([]*image.V1Image, len(m.FSLayers))
	for i := range m.FSLayers {
		img := &image.V1Image{}

		if err := json.Unmarshal([]byte(m.History[i].V1Compatibility), img); err != nil {
			return err
		}

		imgs[i] = img
		if err := v1.ValidateID(img.ID); err != nil {
			return err
		}
	}

	if imgs[len(imgs)-1].Parent != "" && runtime.GOOS != "windows" {
		// Windows base layer can point to a base layer parent that is not in manifest.
		return errors.New("Invalid parent ID in the base layer of the image.")
	}

	// check general duplicates to error instead of a deadlock
	idmap := make(map[string]struct{})

	var lastID string
	for _, img := range imgs {
		// skip IDs that appear after each other, we handle those later
		if _, exists := idmap[img.ID]; img.ID != lastID && exists {
			return fmt.Errorf("ID %+v appears multiple times in manifest", img.ID)
		}
		lastID = img.ID
		idmap[lastID] = struct{}{}
	}

	// backwards loop so that we keep the remaining indexes after removing items
	for i := len(imgs) - 2; i >= 0; i-- {
		if imgs[i].ID == imgs[i+1].ID { // repeated ID. remove and continue
			m.FSLayers = append(m.FSLayers[:i], m.FSLayers[i+1:]...)
			m.History = append(m.History[:i], m.History[i+1:]...)
		} else if imgs[i].Parent != imgs[i+1].ID {
			return fmt.Errorf("Invalid parent ID. Expected %v, got %v.", imgs[i+1].ID, imgs[i].Parent)
		}
	}

	return nil
}

// CalculateLayerChecksums walks an old graph directory and calculates checksums
// for each layer. These checksums are later used for migration.
func CalculateLayerChecksums(root string, ls checksumCalculator, mappings map[string]image.ID) {
	graphDir := filepath.Join(root, graphDirName)
	// spawn some extra workers also for maximum performance because the process is bounded by both cpu and io
	workers := runtime.NumCPU() * 3
	workQueue := make(chan string, workers)

	wg := sync.WaitGroup{}

	for i := 0; i < workers; i++ {
		wg.Add(1)
		go func() {
			for id := range workQueue {
				start := time.Now()
				if err := calculateLayerChecksum(graphDir, id, ls); err != nil {
					logrus.Errorf("could not calculate checksum for %q, %q", id, err)
				}
				elapsed := time.Since(start)
				logrus.Debugf("layer %s took %.2f seconds", id, elapsed.Seconds())
			}
			wg.Done()
		}()
	}

	dir, err := ioutil.ReadDir(graphDir)
	if err != nil {
		logrus.Errorf("could not read directory %q", graphDir)
		return
	}
	for _, v := range dir {
		v1ID := v.Name()
		if err := imagev1.ValidateID(v1ID); err != nil {
			continue
		}
		if _, ok := mappings[v1ID]; ok { // support old migrations without helper files
			continue
		}
		workQueue <- v1ID
	}
	close(workQueue)
	wg.Wait()
}

func migrateImages(root string, ls graphIDRegistrar, is image.Store, ms metadata.Store, mappings map[string]image.ID) error {
	graphDir := filepath.Join(root, graphDirName)

	dir, err := ioutil.ReadDir(graphDir)
	if err != nil {
		return err
	}
	for _, v := range dir {
		v1ID := v.Name()
		if err := imagev1.ValidateID(v1ID); err != nil {
			continue
		}
		if _, exists := mappings[v1ID]; exists {
			continue
		}
		if err := migrateImage(v1ID, root, ls, is, ms, mappings); err != nil {
			continue
		}
	}

	return nil
}

func validateName(name string) error {
	if err := v1.ValidateID(name); err == nil {
		return fmt.Errorf("Invalid repository name (%s), cannot specify 64-byte hexadecimal strings", name)
	}
	return nil
}

func (p *v1Puller) downloadImage(out io.Writer, repoData *registry.RepositoryData, img *registry.ImgData, layerDownloaded chan struct{}, errors chan error) {
	if img.Tag == "" {
		logrus.Debugf("Image (id: %s) present in this repository but untagged, skipping", img.ID)
		return
	}

	localNameRef, err := reference.WithTag(p.repoInfo.LocalName, img.Tag)
	if err != nil {
		retErr := fmt.Errorf("Image (id: %s) has invalid tag: %s", img.ID, img.Tag)
		logrus.Debug(retErr.Error())
		errors <- retErr
	}

	if err := v1.ValidateID(img.ID); err != nil {
		errors <- err
		return
	}

	out.Write(p.sf.FormatProgress(stringid.TruncateID(img.ID), fmt.Sprintf("Pulling image (%s) from %s", img.Tag, p.repoInfo.CanonicalName.Name()), nil))
	success := false
	var lastErr error
	var isDownloaded bool
	for _, ep := range p.repoInfo.Index.Mirrors {
		ep += "v1/"
		out.Write(p.sf.FormatProgress(stringid.TruncateID(img.ID), fmt.Sprintf("Pulling image (%s) from %s, mirror: %s", img.Tag, p.repoInfo.CanonicalName.Name(), ep), nil))
		if isDownloaded, err = p.pullImage(out, img.ID, ep, localNameRef); err != nil {
			// Don't report errors when pulling from mirrors.
			logrus.Debugf("Error pulling image (%s) from %s, mirror: %s, %s", img.Tag, p.repoInfo.CanonicalName.Name(), ep, err)
			continue
		}
		if isDownloaded {
			layerDownloaded <- struct{}{}
		}
		success = true
		break
	}
	if !success {
		for _, ep := range repoData.Endpoints {
			out.Write(p.sf.FormatProgress(stringid.TruncateID(img.ID), fmt.Sprintf("Pulling image (%s) from %s, endpoint: %s", img.Tag, p.repoInfo.CanonicalName.Name(), ep), nil))
			if isDownloaded, err = p.pullImage(out, img.ID, ep, localNameRef); err != nil {
				// It's not ideal that only the last error is returned, it would be better to concatenate the errors.
				// As the error is also given to the output stream the user will see the error.
				lastErr = err
				out.Write(p.sf.FormatProgress(stringid.TruncateID(img.ID), fmt.Sprintf("Error pulling image (%s) from %s, endpoint: %s, %s", img.Tag, p.repoInfo.CanonicalName.Name(), ep, err), nil))
				continue
			}
			if isDownloaded {
				layerDownloaded <- struct{}{}
			}
			success = true
			break
		}
	}
	if !success {
		err := fmt.Errorf("Error pulling image (%s) from %s, %v", img.Tag, p.repoInfo.CanonicalName.Name(), lastErr)
		out.Write(p.sf.FormatProgress(stringid.TruncateID(img.ID), err.Error(), nil))
		errors <- err
		return
	}
	out.Write(p.sf.FormatProgress(stringid.TruncateID(img.ID), "Download complete", nil))
}