chore: Clearest implementation of urn package.

internal/core/services/claims.go

@@ -653,7 +653,7 @@ func (c *claim) getAgentCredential(ctx context.Context, basicMessage *ports.Agen
 		return nil, fmt.Errorf("invalid credential fetch request body: %w", err)
 	}
 
-	claimID, err := urn.Parse(urn.URN(fetchRequestBody.ID))
+	claimID, err := urn.UUIDFromURNString(fetchRequestBody.ID)
 	if err != nil {
 		claimID, err = uuid.Parse(fetchRequestBody.ID)
 		if err != nil {

internal/urn/urn.go

@@ -14,13 +14,37 @@ func FromUUID(uuid uuid.UUID) URN {
 	return URN("urn:uuid:" + uuid.String())
 }
 
-// Parse extracts a UUID from a URN.
-func Parse(u URN) (uuid.UUID, error) {
+// UUID returns the UUID from a URN. It can throw an error to prevent bad constructor calls or urns without uuids
+func (u URN) UUID() (uuid.UUID, error) {
+	if err := u.valid(); err != nil {
+		return uuid.Nil, err
+	}
+	return uuid.Parse(string(u[9:]))
+}
+
+func (u URN) valid() error {
 	if len(u) < len("urn:uuid:") {
-		return uuid.UUID{}, errors.New("invalid uuid URN length")
+		return errors.New("invalid uuid URN length")
 	}
 	if u[:9] != "urn:uuid:" {
-		return uuid.UUID{}, errors.New("invalid uuid URN prefix")
+		return errors.New("invalid uuid URN prefix")
 	}
-	return uuid.Parse(string(u[9:]))
+	return nil
+}
+
+// Parse creates a URN from a string.
+func Parse(u string) (URN, error) {
+	if err := URN(u).valid(); err != nil {
+		return "", err
+	}
+	return URN(u), nil
+}
+
+// UUIDFromURNString returns the UUID from a URN string.
+func UUIDFromURNString(s string) (uuid.UUID, error) {
+	urn, err := Parse(s)
+	if err != nil {
+		return uuid.Nil, err
+	}
+	return urn.UUID()
 }

internal/urn/urn_test.go

@@ -14,7 +14,7 @@ func TestFromUUID(t *testing.T) {
 	assert.Equal(t, "urn:uuid:"+id.String(), string(urn))
 }
 
-func TestParse(t *testing.T) {
+func TestUUIDFromURNString(t *testing.T) {
 	for _, ts := range []struct {
 		urn string
 		err error
@@ -25,7 +25,7 @@ func TestParse(t *testing.T) {
 		{"urn:uuid:123e4567-e89b-12d3-a456-426614174000", nil},
 	} {
 		t.Run(ts.urn, func(t *testing.T) {
-			u, err := Parse(URN(ts.urn))
+			u, err := UUIDFromURNString(ts.urn)
 			if err == nil {
 				assert.Equal(t, ts.urn[9:], u.String())
 			} else {