Check for existance

Signed-off-by: jolheiser <john.olheiser@gmail.com>

registry/error.go

@@ -2,6 +2,19 @@ package registry
 
 import "fmt"
 
+type ErrTemplateExists struct {
+	Name string
+}
+
+func (e ErrTemplateExists) Error() string {
+	return fmt.Sprintf("template %s already exists", e.Name)
+}
+
+func IsErrTemplateExists(err error) bool {
+	_, ok := err.(ErrTemplateExists)
+	return ok
+}
+
 type ErrTemplateNotFound struct {
 	Name string
 }

registry/registry.go

@@ -50,6 +50,10 @@ func (r *Registry) GetTemplate(name string) (*Template, error) {
 
 // DownloadTemplate downloads and adds a new Template to the Registry
 func (r *Registry) DownloadTemplate(name, repo, branch string) (*Template, error) {
+	if _, err := r.GetTemplate(name); err == nil {
+		return nil, ErrTemplateExists{Name: name}
+	}
+
 	t := &Template{
 		reg:        r,
 		Name:       name,
@@ -68,6 +72,10 @@ func (r *Registry) DownloadTemplate(name, repo, branch string) (*Template, error
 
 // SaveTemplate saves a local Template to the Registry
 func (r *Registry) SaveTemplate(name, path string) (*Template, error) {
+	if _, err := r.GetTemplate(name); err == nil {
+		return nil, ErrTemplateExists{Name: name}
+	}
+
 	t := &Template{
 		reg:        r,
 		Name:       name,