Refactor package types to use dedicated schema types per package type (NPM, PyPI, NuGet, OCI, MCPB) (#634)

internal/validators/registries/oci_ref_parser.go

@@ -0,0 +1,161 @@
+package registries
+
+import (
+	"fmt"
+	"regexp"
+	"strings"
+)
+
+const (
+	// defaultOCIRegistry is the default registry when none is specified
+	defaultOCIRegistry = "docker.io"
+	// defaultOCINamespace is the default namespace for official images
+	defaultOCINamespace = "library"
+)
+
+// OCIReference represents a parsed OCI image reference
+type OCIReference struct {
+	Registry  string // e.g., "ghcr.io", "docker.io"
+	Namespace string // e.g., "owner", "library"
+	Image     string // e.g., "repo"
+	Tag       string // e.g., "v1.0.0", "latest" (optional)
+	Digest    string // e.g., "sha256:abc..." (optional)
+}
+
+// ParseOCIReference parses a canonical OCI image reference.
+// Supported formats:
+//   - registry/namespace/image:tag
+//   - registry/namespace/image@digest
+//   - registry/namespace/image:tag@digest
+//   - namespace/image:tag (defaults to docker.io)
+//   - image:tag (defaults to docker.io/library)
+func ParseOCIReference(ref string) (*OCIReference, error) {
+	if ref == "" {
+		return nil, fmt.Errorf("OCI reference cannot be empty")
+	}
+
+	result := &OCIReference{}
+
+	// Split by @ to separate digest
+	var mainPart string
+	if idx := strings.Index(ref, "@"); idx >= 0 {
+		mainPart = ref[:idx]
+		result.Digest = ref[idx+1:]
+
+		// Validate digest format
+		if !strings.HasPrefix(result.Digest, "sha256:") {
+			return nil, fmt.Errorf("invalid digest format: must start with 'sha256:'")
+		}
+		digestPattern := regexp.MustCompile(`^sha256:[a-fA-F0-9]{64}$`)
+		if !digestPattern.MatchString(result.Digest) {
+			return nil, fmt.Errorf("invalid digest format: must be sha256 followed by 64 hex characters")
+		}
+	} else {
+		mainPart = ref
+	}
+
+	// Split by : to separate tag
+	var pathPart string
+	if idx := strings.LastIndex(mainPart, ":"); idx >= 0 {
+		// Check if this looks like a registry with port (e.g., localhost:5000)
+		// or a tag. If there's a / after the :, it's likely a port.
+		if idx > 0 && !strings.Contains(mainPart[idx:], "/") {
+			pathPart = mainPart[:idx]
+			result.Tag = mainPart[idx+1:]
+		} else {
+			pathPart = mainPart
+		}
+	} else {
+		pathPart = mainPart
+	}
+
+	// Parse the path (registry/namespace/image or namespace/image or image)
+	parts := strings.Split(pathPart, "/")
+
+	switch len(parts) {
+	case 1:
+		// Just image name: "postgres:16" -> docker.io/library/postgres:16
+		result.Registry = defaultOCIRegistry
+		result.Namespace = defaultOCINamespace
+		result.Image = parts[0]
+
+	case 2:
+		// namespace/image: "owner/repo:tag" -> docker.io/owner/repo:tag
+		// OR registry/image: "ghcr.io/image" -> ghcr.io/library/image
+		// Heuristic: if first part looks like a domain (contains . or :), treat as registry
+		if strings.Contains(parts[0], ".") || strings.Contains(parts[0], ":") {
+			result.Registry = parts[0]
+			result.Namespace = defaultOCINamespace
+			result.Image = parts[1]
+		} else {
+			result.Registry = defaultOCIRegistry
+			result.Namespace = parts[0]
+			result.Image = parts[1]
+		}
+
+	case 3:
+		// registry/namespace/image: "ghcr.io/owner/repo:tag"
+		result.Registry = parts[0]
+		result.Namespace = parts[1]
+		result.Image = parts[2]
+
+	default:
+		// More than 3 parts could be multi-level namespace (e.g., ghcr.io/org/team/repo)
+		// Take first as registry, last as image, everything in between as namespace
+		if len(parts) > 3 {
+			result.Registry = parts[0]
+			result.Namespace = strings.Join(parts[1:len(parts)-1], "/")
+			result.Image = parts[len(parts)-1]
+		} else {
+			return nil, fmt.Errorf("invalid OCI reference format: %s", ref)
+		}
+	}
+
+	// Validate we have either a tag or digest
+	if result.Tag == "" && result.Digest == "" {
+		return nil, fmt.Errorf("OCI reference must include either a tag or digest: %s", ref)
+	}
+
+	// Default tag to "latest" if only digest is provided (for display purposes)
+	// Note: when pulling by digest, the tag is ignored by registries
+	if result.Tag == "" && result.Digest != "" {
+		result.Tag = "latest"
+	}
+
+	return result, nil
+}
+
+// String returns the canonical string representation of the OCI reference
+func (r *OCIReference) String() string {
+	var sb strings.Builder
+
+	sb.WriteString(r.Registry)
+	sb.WriteString("/")
+	sb.WriteString(r.Namespace)
+	sb.WriteString("/")
+	sb.WriteString(r.Image)
+
+	if r.Tag != "" {
+		sb.WriteString(":")
+		sb.WriteString(r.Tag)
+	}
+
+	if r.Digest != "" {
+		sb.WriteString("@")
+		sb.WriteString(r.Digest)
+	}
+
+	return sb.String()
+}
+
+// GetRegistryBaseURL returns the full registry URL (e.g., "https://docker.io" or "https://ghcr.io")
+func (r *OCIReference) GetRegistryBaseURL() string {
+	switch r.Registry {
+	case "docker.io", "registry.docker.io", "index.docker.io":
+		return "https://docker.io"
+	case "ghcr.io":
+		return "https://ghcr.io"
+	default:
+		return "https://" + r.Registry
+	}
+}