fix(showcase): exclude backup-suffixed repositories

2 files changed, 134 insertions, 12 deletions

diff --git a/internal/showcase/showcase.go b/internal/showcase/showcase.go
index a8770a2..19a9a89 100644
--- a/internal/showcase/showcase.go
+++ b/internal/showcase/showcase.go
@@ -815,23 +815,13 @@ func (g *Generator) verifyImages(summary *ProjectSummary) error {
 
 // filterExcludedRepos filters out repositories that are in the exclusion list
 func (g *Generator) filterExcludedRepos(repos []string) []string {
-	if len(g.config.ExcludeFromShowcase) == 0 {
-		return repos
-	}
-
-	// Create a map for quick lookup
-	excludeMap := make(map[string]bool)
-	for _, excluded := range g.config.ExcludeFromShowcase {
-		excludeMap[excluded] = true
-	}
-
 	// Filter repositories
 	var filtered []string
 	for _, repo := range repos {
-		if !excludeMap[repo] {
+		if !g.isExcluded(repo) {
 			filtered = append(filtered, repo)
 		} else {
-			fmt.Printf("Excluding repository from showcase: %s\n", repo)
+			fmt.Printf("Excluding repository from showcase (%s): %s\n", g.exclusionReason(repo), repo)
 		}
 	}
 
@@ -840,6 +830,10 @@ func (g *Generator) filterExcludedRepos(repos []string) []string {
 
 // isExcluded checks if a repository is in the exclusion list
 func (g *Generator) isExcluded(repo string) bool {
+	if isBackupRepo(repo) {
+		return true
+	}
+
 	for _, excluded := range g.config.ExcludeFromShowcase {
 		if excluded == repo {
 			return true
@@ -848,6 +842,34 @@ func (g *Generator) isExcluded(repo string) bool {
 	return false
 }
 
+// exclusionReason returns why a repository is excluded from showcase generation.
+func (g *Generator) exclusionReason(repo string) string {
+	var reasons []string
+
+	if isBackupRepo(repo) {
+		reasons = append(reasons, "backup suffix")
+	}
+
+	for _, excluded := range g.config.ExcludeFromShowcase {
+		if excluded == repo {
+			reasons = append(reasons, "config")
+			break
+		}
+	}
+
+	if len(reasons) == 0 {
+		return "unknown reason"
+	}
+
+	return strings.Join(reasons, ", ")
+}
+
+// isBackupRepo checks whether a repository name has a backup suffix.
+// Excluded patterns: *.bak and *.bak.*
+func isBackupRepo(repo string) bool {
+	return strings.HasSuffix(repo, ".bak") || strings.Contains(repo, ".bak.")
+}
+
 // formatNumber formats a number with thousands separators
 func formatNumber(n int) string {
 	str := fmt.Sprintf("%d", n)
diff --git a/internal/showcase/showcase_test.go b/internal/showcase/showcase_test.go
new file mode 100644
index 0000000..284a6bc
--- /dev/null
+++ b/internal/showcase/showcase_test.go
@@ -0,0 +1,100 @@
+package showcase
+
+import (
+	"reflect"
+	"testing"
+
+	"codeberg.org/snonux/gitsyncer/internal/config"
+)
+
+func TestIsBackupRepo(t *testing.T) {
+	t.Parallel()
+
+	tests := []struct {
+		name string
+		repo string
+		want bool
+	}{
+		{name: "exact bak suffix", repo: "foo.bak", want: true},
+		{name: "bak dot suffix", repo: "foo.bak.20260222", want: true},
+		{name: "bak dot with multiple segments", repo: "foo.bak.tmp.snapshot", want: true},
+		{name: "backup word", repo: "foo.backup", want: false},
+		{name: "bak as prefix", repo: "bak.foo", want: false},
+	}
+
+	for _, tc := range tests {
+		tc := tc
+		t.Run(tc.name, func(t *testing.T) {
+			t.Parallel()
+			got := isBackupRepo(tc.repo)
+			if got != tc.want {
+				t.Fatalf("isBackupRepo(%q) = %v, want %v", tc.repo, got, tc.want)
+			}
+		})
+	}
+}
+
+func TestIsExcluded_AdditiveRules(t *testing.T) {
+	t.Parallel()
+
+	g := &Generator{
+		config: &config.Config{
+			ExcludeFromShowcase: []string{"manual-exclude"},
+		},
+	}
+
+	tests := []struct {
+		name string
+		repo string
+		want bool
+	}{
+		{name: "excluded by config", repo: "manual-exclude", want: true},
+		{name: "excluded by backup suffix", repo: "repo.bak", want: true},
+		{name: "not excluded", repo: "normal-repo", want: false},
+	}
+
+	for _, tc := range tests {
+		tc := tc
+		t.Run(tc.name, func(t *testing.T) {
+			t.Parallel()
+			got := g.isExcluded(tc.repo)
+			if got != tc.want {
+				t.Fatalf("isExcluded(%q) = %v, want %v", tc.repo, got, tc.want)
+			}
+		})
+	}
+}
+
+func TestFilterExcludedRepos_RemovesBackupAndConfigRepos(t *testing.T) {
+	t.Parallel()
+
+	g := &Generator{
+		config: &config.Config{
+			ExcludeFromShowcase: []string{"manual-exclude"},
+		},
+	}
+
+	repos := []string{"normal", "manual-exclude", "mirror.bak", "mirror.bak.20260222", "keep"}
+	want := []string{"normal", "keep"}
+
+	got := g.filterExcludedRepos(repos)
+	if !reflect.DeepEqual(got, want) {
+		t.Fatalf("filterExcludedRepos() = %#v, want %#v", got, want)
+	}
+}
+
+func TestFilterExcludedRepos_EmptyConfigStillRemovesBackupRepos(t *testing.T) {
+	t.Parallel()
+
+	g := &Generator{
+		config: &config.Config{},
+	}
+
+	repos := []string{"normal", "archive.bak", "archive.bak.old", "keep"}
+	want := []string{"normal", "keep"}
+
+	got := g.filterExcludedRepos(repos)
+	if !reflect.DeepEqual(got, want) {
+		t.Fatalf("filterExcludedRepos() = %#v, want %#v", got, want)
+	}
+}