feat(bundler): Add template bundler

pkg/bundler/template_bundler.go

@@ -0,0 +1,74 @@
+package bundler
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+)
+
+// The TemplateBundler handles bundling of jsonnet templates and related template files.
+// It copies template files from the contexts/_template directory to the artifact build
+// directory. The TemplateBundler ensures that all template dependencies are properly
+// bundled for distribution with the artifact.
+
+// =============================================================================
+// Types
+// =============================================================================
+
+// TemplateBundler handles bundling of template files
+type TemplateBundler struct {
+	BaseBundler
+}
+
+// =============================================================================
+// Constructor
+// =============================================================================
+
+// NewTemplateBundler creates a new TemplateBundler instance
+func NewTemplateBundler() *TemplateBundler {
+	return &TemplateBundler{
+		BaseBundler: *NewBaseBundler(),
+	}
+}
+
+// =============================================================================
+// Public Methods
+// =============================================================================
+
+// Bundle adds template files from contexts/_template directory to the artifact by recursively walking the directory tree.
+// It validates that the templates directory exists, then walks through all files preserving the directory structure.
+// Each file is read and added to the artifact with the path prefix "_template/" to maintain organization.
+// Directories are skipped and only regular files are processed for bundling.
+func (t *TemplateBundler) Bundle(artifact Artifact) error {
+	templatesSource := filepath.Join("contexts", "_template")
+
+	if _, err := t.shims.Stat(templatesSource); os.IsNotExist(err) {
+		return fmt.Errorf("templates directory not found: %s", templatesSource)
+	}
+
+	return t.shims.Walk(templatesSource, func(path string, info os.FileInfo, err error) error {
+		if err != nil {
+			return err
+		}
+
+		if info.IsDir() {
+			return nil
+		}
+
+		relPath, err := t.shims.FilepathRel(templatesSource, path)
+		if err != nil {
+			return fmt.Errorf("failed to get relative path: %w", err)
+		}
+
+		data, err := t.shims.ReadFile(path)
+		if err != nil {
+			return fmt.Errorf("failed to read template file %s: %w", path, err)
+		}
+
+		artifactPath := "_template/" + filepath.ToSlash(relPath)
+		return artifact.AddFile(artifactPath, data)
+	})
+}
+
+// Ensure TemplateBundler implements Bundler interface
+var _ Bundler = (*TemplateBundler)(nil)