Allow sync to workspace path (#170)

With this change:
* Paths under `/Workspace/<me>` and `/Repos/<me>` are allowed
* The sync destination is checked to be either a directory or a repository
* If it is under `/Repos` and doesn't exist, the command returns an error

cmd/sync/sync.go

@@ -1,17 +1,95 @@
 package sync
 
 import (
+	"context"
 	"fmt"
 	"log"
+	"strings"
 	"time"
 
 	"github.com/databricks/bricks/cmd/root"
 	"github.com/databricks/bricks/cmd/sync/repofiles"
 	"github.com/databricks/bricks/git"
 	"github.com/databricks/bricks/project"
+	"github.com/databricks/databricks-sdk-go"
+	"github.com/databricks/databricks-sdk-go/apierr"
+	"github.com/databricks/databricks-sdk-go/service/scim"
+	"github.com/databricks/databricks-sdk-go/service/workspace"
 	"github.com/spf13/cobra"
 )
 
+func matchesBasePaths(me *scim.User, path string) error {
+	basePaths := []string{
+		fmt.Sprintf("/Users/%s/", me.UserName),
+		fmt.Sprintf("/Repos/%s/", me.UserName),
+	}
+	basePathMatch := false
+	for _, basePath := range basePaths {
+		if strings.HasPrefix(path, basePath) {
+			basePathMatch = true
+			break
+		}
+	}
+	if !basePathMatch {
+		return fmt.Errorf("path must be nested under %s or %s", basePaths[0], basePaths[1])
+	}
+	return nil
+}
+
+// ensureRemotePathIsUsable checks if the specified path is nested under
+// expected base paths and if it is a directory or repository.
+func ensureRemotePathIsUsable(ctx context.Context, wsc *databricks.WorkspaceClient, me *scim.User, path string) error {
+	err := matchesBasePaths(me, path)
+	if err != nil {
+		return err
+	}
+
+	// Ensure that the remote path exits.
+	// If it is a repo, it has to exist.
+	// If it is a workspace path, it may not exist.
+	info, err := wsc.Workspace.GetStatusByPath(ctx, path)
+	if err != nil {
+		// We only deal with 404s below.
+		if !apierr.IsMissing(err) {
+			return err
+		}
+
+		switch {
+		case strings.HasPrefix(path, "/Repos/"):
+			return fmt.Errorf("%s does not exist; please create it first", path)
+		case strings.HasPrefix(path, "/Users/"):
+			// The workspace path doesn't exist. Create it and try again.
+			err = wsc.Workspace.MkdirsByPath(ctx, path)
+			if err != nil {
+				return fmt.Errorf("unable to create directory at %s: %w", path, err)
+			}
+			info, err = wsc.Workspace.GetStatusByPath(ctx, path)
+			if err != nil {
+				return err
+			}
+		default:
+			return err
+		}
+	}
+
+	log.Printf(
+		"[DEBUG] Path %s has type %s (ID: %d)",
+		info.Path,
+		strings.ToLower(info.ObjectType.String()),
+		info.ObjectId,
+	)
+
+	// We expect the object at path to be a directory or a repo.
+	switch info.ObjectType {
+	case workspace.ObjectTypeDirectory:
+		return nil
+	case workspace.ObjectTypeRepo:
+		return nil
+	}
+
+	return fmt.Errorf("%s points to a %s", path, strings.ToLower(info.ObjectType.String()))
+}
+
 // syncCmd represents the sync command
 var syncCmd = &cobra.Command{
 	Use:   "sync",
@@ -23,11 +101,12 @@ var syncCmd = &cobra.Command{
 		prj := project.Get(ctx)
 		wsc := prj.WorkspacesClient()
 
+		me, err := prj.Me()
+		if err != nil {
+			return err
+		}
+
 		if *remotePath == "" {
-			me, err := prj.Me()
-			if err != nil {
-				return err
-			}
 			repositoryName, err := git.RepositoryName()
 			if err != nil {
 				return err
@@ -36,13 +115,10 @@ var syncCmd = &cobra.Command{
 		}
 
 		log.Printf("[INFO] Remote file sync location: %v", *remotePath)
-		repoExists, err := git.RepoExists(*remotePath, ctx, wsc)
+		err = ensureRemotePathIsUsable(ctx, wsc, me, *remotePath)
 		if err != nil {
 			return err
 		}
-		if !repoExists {
-			return fmt.Errorf("repo not found, please ensure %s exists", *remotePath)
-		}
 
 		root := prj.Root()
 		repoFiles := repofiles.Create(*remotePath, root, wsc)