refactor!: un-export namespace.ValidateBlobNamespace (#2145)

Closes celestiaorg/celestia-app#2143

De-duplicate `ValidateBlobNamespace` and export it from `x/blob/types`
package. The namespace package needs to define its own `isBlobNamespace`
because it can't import `ValidateBlobNamespace` from `x/blob/types` as
that would introduce a circular dependency.

pkg/namespace/consts.go

@@ -67,4 +67,7 @@ var (
 		Version: math.MaxUint8,
 		ID:      bytes.Repeat([]byte{0xFF}, NamespaceIDSize),
 	}
+
+	// SupportedBlobNamespaceVersions is a list of namespace versions that can be specified by a user for blobs.
+	SupportedBlobNamespaceVersions = []uint8{NamespaceVersionZero}
 )

pkg/namespace/namespace.go

@@ -12,7 +12,7 @@ type Namespace struct {
 
 // New returns a new namespace with the provided version and id.
 func New(version uint8, id []byte) (Namespace, error) {
-	err := validateVersion(version)
+	err := validateVersionSupported(version)
 	if err != nil {
 		return Namespace{}, err
 	}
@@ -83,25 +83,8 @@ func (n Namespace) Bytes() []byte {
 	return append([]byte{n.Version}, n.ID...)
 }
 
-// ValidateBlobNamespace returns an error if this namespace is not a valid blob namespace.
-func (n Namespace) ValidateBlobNamespace() error {
-	if n.IsReserved() {
-		return fmt.Errorf("invalid blob namespace: %v cannot use a reserved namespace ID, want > %v", n.Bytes(), MaxReservedNamespace.Bytes())
-	}
-
-	if n.IsParityShares() {
-		return fmt.Errorf("invalid blob namespace: %v cannot use parity shares namespace ID", n.Bytes())
-	}
-
-	if n.IsTailPadding() {
-		return fmt.Errorf("invalid blob namespace: %v cannot use tail padding namespace ID", n.Bytes())
-	}
-
-	return nil
-}
-
-// validateVersion returns an error if the version is not supported.
-func validateVersion(version uint8) error {
+// validateVersionSupported returns an error if the version is not supported.
+func validateVersionSupported(version uint8) error {
 	if version != NamespaceVersionZero && version != NamespaceVersionMax {
 		return fmt.Errorf("unsupported namespace version %v", version)
 	}

pkg/namespace/random_blob.go

@@ -2,6 +2,7 @@ package namespace
 
 import (
 	tmrand "github.com/tendermint/tendermint/libs/rand"
+	"golang.org/x/exp/slices"
 )
 
 func RandomBlobNamespaceID() []byte {
@@ -22,11 +23,9 @@ func RandomBlobNamespaceWithPRG(prg *tmrand.Rand) Namespace {
 	for {
 		id := RandomBlobNamespaceIDWithPRG(prg)
 		namespace := MustNewV0(id)
-		err := namespace.ValidateBlobNamespace()
-		if err != nil {
-			continue
+		if isBlobNamespace(namespace) {
+			return namespace
 		}
-		return namespace
 	}
 }
 
@@ -36,3 +35,25 @@ func RandomBlobNamespaces(rand *tmrand.Rand, count int) (namespaces []Namespace)
 	}
 	return namespaces
 }
+
+// isBlobNamespace returns an true if this namespace is a valid user-specifiable
+// blob namespace.
+func isBlobNamespace(ns Namespace) bool {
+	if ns.IsReserved() {
+		return false
+	}
+
+	if ns.IsParityShares() {
+		return false
+	}
+
+	if ns.IsTailPadding() {
+		return false
+	}
+
+	if !slices.Contains(SupportedBlobNamespaceVersions, ns.Version) {
+		return false
+	}
+
+	return true
+}