move check into a type-specific method rather than delegating it to c…

…aller

Signed-off-by: Bob Callaway <bcallaway@google.com>

cmd/rekor-cli/app/pflag_groups.go

@@ -26,8 +26,6 @@ import (
 	"github.com/sigstore/rekor/pkg/types"
 	"github.com/spf13/cobra"
 	"github.com/spf13/viper"
-
-	"golang.org/x/exp/slices"
 )
 
 // addFlagToCmd adds the specified command of a specified type to the command's flag set
@@ -188,7 +186,7 @@ func ParseTypeFlag(typeStr string) (string, string, error) {
 	case 1:
 		return typeStrings[0], "", nil
 	case 2:
-		if !slices.Contains(ti.SupportedVersions(), typeStrings[1]) {
+		if !ti.IsSupportedVersion(typeStrings[1]) {
 			return "", "", fmt.Errorf("type %v does not support version %v", typeStrings[0], typeStrings[1])
 		}
 		return typeStrings[0], typeStrings[1], nil

pkg/types/types.go

@@ -23,6 +23,7 @@ import (
 
 	"github.com/sigstore/rekor/pkg/generated/models"
 	"github.com/sigstore/rekor/pkg/log"
+	"golang.org/x/exp/slices"
 )
 
 // TypeMap stores mapping between type strings and entry constructors
@@ -42,6 +43,7 @@ type TypeImpl interface {
 	CreateProposedEntry(context.Context, string, ArtifactProperties) (models.ProposedEntry, error)
 	DefaultVersion() string
 	SupportedVersions() []string
+	IsSupportedVersion(string) bool
 	UnmarshalEntry(pe models.ProposedEntry) (EntryImpl, error)
 }
 
@@ -62,10 +64,16 @@ func (rt *RekorType) VersionedUnmarshal(pe models.ProposedEntry, version string)
 	return entry, entry.Unmarshal(pe)
 }
 
+// SupportedVersions returns a list of versions of this type that can be currently entered into the log
 func (rt *RekorType) SupportedVersions() []string {
 	return rt.VersionMap.SupportedVersions()
 }
 
+// IsSupportedVersion returns true if the version can be inserted into the log, and false if not
+func (rt *RekorType) IsSupportedVersion(proposedVersion string) bool {
+	return slices.Contains(rt.SupportedVersions(), proposedVersion)
+}
+
 // ListImplementedTypes returns a list of all type strings currently known to
 // be implemented
 func ListImplementedTypes() []string {