refactoring sync

pkg/remote/client/client.go

@@ -384,6 +384,10 @@ func (c *Client) All() ([]repository.Metadata, error) {
 	return nil, errors.New("invalid payload sent by the server")
 }
 
+func (c *Client) BaseURL() string {
+	return c.baseURL
+}
+
 func (c *Client) get(url string) (obj.HTTPObject, error) {
 	cli := http.Client{}
 

pkg/sync/sync.go

@@ -1,2 +1,235 @@
 package sync
 
+import (
+	"cloudsave/pkg/data"
+	"cloudsave/pkg/remote"
+	"cloudsave/pkg/remote/client"
+	"cloudsave/pkg/repository"
+	"errors"
+	"fmt"
+)
+
+type (
+	ConflictResolution int
+	State              int
+	decision           int
+
+	Syncer struct {
+		cli     *client.Client
+		service *data.Service
+
+		stateCallback    func(s State, g repository.Metadata)
+		errorCallback    func(err error)
+		conflictCallback func(a, b repository.Metadata) ConflictResolution
+	}
+)
+
+const (
+	Their ConflictResolution = iota
+	Mine
+	None
+)
+
+const (
+	ignore decision = iota
+	push
+	pull
+)
+
+const (
+	FetchingMetdata State = iota
+	Pushing
+	Pulling
+	Pushed
+	Pulled
+	UpToDate
+)
+
+var (
+	ErrFetching  error = errors.New("failed to fetch the metadata")
+	ErrPushing   error = errors.New("failed to push data")
+	ErrPulling   error = errors.New("failed to pull data")
+	ErrDatastore error = errors.New("failed to get data from local datastore")
+)
+
+func NewSyncer(cli *client.Client, service *data.Service) *Syncer {
+	return &Syncer{
+		cli:     cli,
+		service: service,
+	}
+}
+
+func (s *Syncer) SetStateCallback(fn func(s State, g repository.Metadata)) {
+	s.stateCallback = fn
+}
+
+func (s *Syncer) SetErrorCallback(fn func(err error)) {
+	s.errorCallback = fn
+}
+
+func (s *Syncer) SetConflictCallback(fn func(a, b repository.Metadata) ConflictResolution) {
+	s.conflictCallback = fn
+}
+
+func (s *Syncer) Sync() {
+	games, err := s.service.AllGames()
+	if err != nil {
+		s.errorCallback(fmt.Errorf("failed to get all games: %w", err))
+		return
+	}
+
+	for _, g := range games {
+		r, err := remote.One(g.ID)
+		if err != nil {
+			s.errorCallback(fmt.Errorf("%w: %s", ErrDatastore, err))
+		}
+		if r.URL != s.cli.BaseURL() {
+			continue
+		}
+		if err := s.sync(g); err != nil {
+			s.errorCallback(err)
+		}
+	}
+}
+
+func (s *Syncer) sync(g repository.Metadata) error {
+	s.stateCallback(FetchingMetdata, g)
+
+	remoteMetadata, err := s.cli.Metadata(g.ID)
+	if err != nil {
+		if errors.Is(err, client.ErrNotFound) {
+			s.stateCallback(Pushing, g)
+			if err := s.push(g); err != nil {
+				return fmt.Errorf("%w: %s", ErrPushing, err)
+			}
+			s.stateCallback(Pushed, g)
+			return nil
+		}
+		return fmt.Errorf("%w: %s", ErrFetching, err)
+	}
+
+	if g.MD5 == remoteMetadata.MD5 {
+		s.stateCallback(UpToDate, g)
+		return nil
+	}
+
+	d := ignore
+
+	if g.Version > remoteMetadata.Version {
+		d = push
+	}
+
+	if g.Version < remoteMetadata.Version {
+		d = pull
+	}
+
+	if g.Version == remoteMetadata.Version {
+		r := s.conflictCallback(g, remoteMetadata)
+		switch r {
+		case Mine:
+			{
+				d = push
+			}
+		case Their:
+			{
+				d = pull
+			}
+		}
+		return nil
+	}
+
+	switch d {
+	case push:
+		{
+			s.stateCallback(Pushing, g)
+			if err := s.push(g); err != nil {
+				return fmt.Errorf("%w: %s", ErrPushing, err)
+			}
+			s.stateCallback(Pushed, g)
+			return nil
+		}
+	case pull:
+		{
+			s.stateCallback(Pulling, g)
+			if err := s.pull(g, remoteMetadata); err != nil {
+				return fmt.Errorf("%w: %s", ErrPulling, err)
+			}
+			s.stateCallback(Pulled, g)
+			return nil
+		}
+	}
+
+	return nil
+}
+
+func (s *Syncer) push(g repository.Metadata) error {
+	if err := s.service.PushArchive(g.ID, "", s.cli); err != nil {
+		return err
+	}
+
+	// manage backup
+	bs, err := s.service.AllBackups(g.ID)
+	if err != nil {
+		return err
+	}
+
+	for _, b := range bs {
+		binfo, err := s.cli.ArchiveInfo(g.ID, b.UUID)
+		if err != nil {
+			if !errors.Is(err, client.ErrNotFound) {
+				return fmt.Errorf("failed to get remote information about the backup file: %w", err)
+			}
+		}
+
+		if binfo.MD5 != b.MD5 {
+			if err := s.cli.PushBackup(b, g); err != nil {
+				return fmt.Errorf("failed to push backup: %w", err)
+			}
+		}
+
+	}
+	return nil
+}
+
+func (s *Syncer) pull(g, r repository.Metadata) error {
+	g.Version = r.Version
+	g.Date = r.Date
+
+	if err := s.service.UpdateMetadata(g.ID, g); err != nil {
+		return err
+	}
+
+	if err := s.service.PullArchive(g.ID, "", s.cli); err != nil {
+		return err
+	}
+
+	if err := s.service.ApplyCurrent(g.ID); err != nil {
+		return err
+	}
+
+	// manage backup
+	bs, err := s.cli.ListArchives(g.ID)
+	if err != nil {
+		return err
+	}
+
+	for _, uuid := range bs {
+		rinfo, err := s.cli.ArchiveInfo(g.ID, uuid)
+		if err != nil {
+			return err
+		}
+
+		linfo, err := s.service.Backup(g.ID, uuid)
+		if err != nil {
+			return err
+		}
+
+		if linfo.MD5 != rinfo.MD5 {
+			if err := s.service.PullBackup(g.ID, uuid, s.cli); err != nil {
+				return err
+			}
+		}
+	}
+
+	return nil
+}