From 52d4a68d86e4fad43cb1d2dedd7e421bc9501266 Mon Sep 17 00:00:00 2001
From: Marcin Bilski <gyamtso@gmail.com>
Date: Wed, 22 Dec 2021 15:35:09 +0100
Subject: [PATCH] Prevent tagging existing remote versions.

---
 pkg/api/api.go  |  9 ++++++---
 pkg/vcs/git.go  |  4 ++--
 pkg/vcs/tags.go | 18 +++++++++++++-----
 3 files changed, 21 insertions(+), 10 deletions(-)

diff --git a/pkg/api/api.go b/pkg/api/api.go
index 09c97e2..8f5a5ae 100644
--- a/pkg/api/api.go
+++ b/pkg/api/api.go
@@ -352,7 +352,10 @@ func (api *api) tag(w http.ResponseWriter, r *http.Request, module, version stri
 		return
 	}
 
-	taggable.Tag(vcs.Version(version), req.Short)
-
-	// TODO(bilus): Response
+	err = taggable.Tag(r.Context(), vcs.Version(version), req.Short)
+	if err != nil {
+		api.log("api.tag", "module", module, "version", version, "error", err)
+		http.Error(w, err.Error(), http.StatusBadRequest)
+		return
+	}
 }
diff --git a/pkg/vcs/git.go b/pkg/vcs/git.go
index 42941d3..89d43c3 100644
--- a/pkg/vcs/git.go
+++ b/pkg/vcs/git.go
@@ -144,10 +144,10 @@ func isVendoredPackage(name string) bool {
 
 func (g *gitVCS) Zip(ctx context.Context, version Version) (io.ReadCloser, error) {
 	dirName := g.module + "@" + string(version)
-	return g.zipUnder(ctx, version, dirName)
+	return g.zipAs(ctx, version, dirName)
 }
 
-func (g *gitVCS) zipUnder(ctx context.Context, version Version, dirName string) (io.ReadCloser, error) {
+func (g *gitVCS) zipAs(ctx context.Context, version Version, dirName string) (io.ReadCloser, error) {
 	g.log("gitVCS.Zip", "module", g.module, "version", version)
 	ci, err := g.commit(ctx, version)
 	if err != nil {
diff --git a/pkg/vcs/tags.go b/pkg/vcs/tags.go
index f198686..55310b0 100644
--- a/pkg/vcs/tags.go
+++ b/pkg/vcs/tags.go
@@ -22,7 +22,7 @@ func NewEphemeralTagStorage() *EphemeralTagStorage {
 	}
 }
 
-func (s *EphemeralTagStorage) Tag(module string, semVer Version, short string) {
+func (s *EphemeralTagStorage) Tag(module string, semVer Version, short string) error {
 	tags := s.tagsByModule[module]
 	tmp := tags[:0]
 	for _, t := range tags {
@@ -31,6 +31,7 @@ func (s *EphemeralTagStorage) Tag(module string, semVer Version, short string) {
 		}
 	}
 	s.tagsByModule[module] = append(tmp, ephemeralTag{semVer, short})
+	return nil
 }
 
 func (s *EphemeralTagStorage) tags(module string) []ephemeralTag {
@@ -46,7 +47,7 @@ type taggableVCS struct {
 }
 
 type Taggable interface {
-	Tag(semVer Version, short string)
+	Tag(ctx context.Context, semVer Version, short string) error
 }
 
 // NewGitWithEphemeralTags return a go-git VCS client implementation that
@@ -61,8 +62,15 @@ func NewGitWithEphemeralTags(l logger, dir string, module string, auth Auth, sto
 	}
 }
 
-func (v *taggableVCS) Tag(semVer Version, short string) {
-	v.storage.Tag(v.module, semVer, short)
+func (v *taggableVCS) Tag(ctx context.Context, semVer Version, short string) error {
+	remoteVersions, err := v.wrapped.List(ctx)
+	if err != nil {
+		return err
+	}
+	if versionExists(remoteVersions, semVer) {
+		return fmt.Errorf("remote version %s already exists for module %s", semVer, v.module)
+	}
+	return v.storage.Tag(v.module, semVer, short)
 }
 
 func (v *taggableVCS) List(ctx context.Context) ([]Version, error) {
@@ -110,7 +118,7 @@ func (v *taggableVCS) Zip(ctx context.Context, version Version) (io.ReadCloser,
 	}
 	// Zip must contain the ephemeral version.
 	dirName := v.module + "@" + string(version)
-	return v.wrapped.zipUnder(ctx, version2, dirName)
+	return v.wrapped.zipAs(ctx, version2, dirName)
 }
 
 func (v *taggableVCS) resolveVersion(ctx context.Context, version Version) (Version, error) {