feat(repo): add LoadIndexFileForEntries to filter index on load

Fixes #32159

- Refactor LoadIndexFile to delegate to LoadIndexFileForEntries(path, nil)
- Accept []string instead of map[string]struct{} for idiomatic public API
- Remove extra blank line before doc comment
- Add unit tests covering nil names, single match, no match, partial match

Co-authored-by: rajarshipal-lab <rajarshipal-lab@users.noreply.github.com>
Co-authored-by: Cloud-Architect-Emma <Cloud-Architect-Emma@users.noreply.github.com>
Signed-off-by: Cloud-Architect-Emma <your@email.com>

pkg/repo/v1/index.go

@@ -104,6 +104,21 @@ func NewIndexFile() *IndexFile {
 
 // LoadIndexFile takes a file at the given path and returns an IndexFile object
 func LoadIndexFile(path string) (*IndexFile, error) {
+	return LoadIndexFileForEntries(path, nil)
+}
+
+// LoadIndexFileForEntries loads an index file but only validates and retains
+// entries matching the provided chart names. Unmatched entries are discarded
+// after unmarshal without validation, reducing memory and CPU overhead.
+// If names is nil, all entries are loaded (equivalent to LoadIndexFile).
+func LoadIndexFileForEntries(path string, names []string) (*IndexFile, error) {
+	var entries map[string]struct{}
+	if names != nil {
+		entries = make(map[string]struct{}, len(names))
+		for _, n := range names {
+			entries[n] = struct{}{}
+		}
+	}
 	b, err := os.ReadFile(path)
 	if err != nil {
 		return nil, err
@@ -112,6 +127,14 @@ func LoadIndexFile(path string) (*IndexFile, error) {
 	if err != nil {
 		return nil, fmt.Errorf("error loading %s: %w", path, err)
 	}
+	if entries != nil {
+		for name := range i.Entries {
+			if _, ok := entries[name]; !ok {
+				delete(i.Entries, name)
+			}
+		}
+	}
+	i.SortEntries()
 	return i, nil
 }
 

pkg/repo/v1/index_test.go

@@ -718,3 +718,59 @@ func TestLoadIndex_DuplicateChartDeps(t *testing.T) {
 		})
 	}
 }
+
+
+func TestLoadIndexFileForEntries(t *testing.T) {
+	// nil names loads all entries
+	t.Run("nil names loads all", func(t *testing.T) {
+		i, err := LoadIndexFileForEntries("testdata/local-index.yaml", nil)
+		if err != nil {
+			t.Fatal(err)
+		}
+		if len(i.Entries) == 0 {
+			t.Fatal("expected entries, got none")
+		}
+	})
+
+	// filter to a specific chart
+	t.Run("filter to one entry", func(t *testing.T) {
+		i, err := LoadIndexFileForEntries("testdata/local-index.yaml", []string{"alpine"})
+		if err != nil {
+			t.Fatal(err)
+		}
+		if len(i.Entries) != 1 {
+			t.Fatalf("expected 1 entry, got %d", len(i.Entries))
+		}
+		if _, ok := i.Entries["alpine"]; !ok {
+			t.Fatal("expected 'alpine' entry")
+		}
+	})
+
+	// no matches returns empty entries
+	t.Run("no matches returns empty", func(t *testing.T) {
+		i, err := LoadIndexFileForEntries("testdata/local-index.yaml", []string{"nonexistent-chart"})
+		if err != nil {
+			t.Fatal(err)
+		}
+		if len(i.Entries) != 0 {
+			t.Fatalf("expected 0 entries, got %d", len(i.Entries))
+		}
+	})
+
+	// partial match retains only matched entries
+	t.Run("partial match", func(t *testing.T) {
+		full, _ := LoadIndexFile("testdata/local-index.yaml")
+		var firstName string
+		for k := range full.Entries {
+			firstName = k
+			break
+		}
+		i, err := LoadIndexFileForEntries("testdata/local-index.yaml", []string{firstName, "nonexistent-chart"})
+		if err != nil {
+			t.Fatal(err)
+		}
+		if len(i.Entries) != 1 {
+			t.Fatalf("expected 1 entry, got %d", len(i.Entries))
+		}
+	})
+}