waddrmgr+wallet: expose LookupAccount

This exposes a mapping of account name to its corresponding key scope
and internal account number to facilitate the use of external APIs by
users.

waddrmgr/manager.go

@@ -1299,6 +1299,25 @@ func ValidateAccountName(name string) error {
 	return nil
 }
 
+// LookupAccount returns the corresponding key scope and account number for the
+// account with the given name.
+func (m *Manager) LookupAccount(ns walletdb.ReadBucket, name string) (KeyScope,
+	uint32, error) {
+
+	m.mtx.RLock()
+	defer m.mtx.RUnlock()
+
+	for keyScope, scopedMgr := range m.scopedManagers {
+		acct, err := scopedMgr.LookupAccount(ns, name)
+		if err == nil {
+			return keyScope, acct, nil
+		}
+	}
+
+	str := fmt.Sprintf("account name '%s' not found", name)
+	return KeyScope{}, 0, managerError(ErrAccountNotFound, str, nil)
+}
+
 // selectCryptoKey selects the appropriate crypto key based on the key type. An
 // error is returned when an invalid key type is specified or the requested key
 // requires the manager to be unlocked when it isn't.

wallet/wallet.go

@@ -1762,6 +1762,22 @@ func (w *Wallet) AccountProperties(scope waddrmgr.KeyScope, acct uint32) (*waddr
 	return props, err
 }
 
+// LookupAccount returns the corresponding key scope and account number for the
+// account with the given name.
+func (w *Wallet) LookupAccount(name string) (waddrmgr.KeyScope, uint32, error) {
+	var (
+		keyScope waddrmgr.KeyScope
+		account  uint32
+	)
+	err := walletdb.View(w.db, func(tx walletdb.ReadTx) error {
+		ns := tx.ReadBucket(waddrmgrNamespaceKey)
+		var err error
+		keyScope, account, err = w.Manager.LookupAccount(ns, name)
+		return err
+	})
+	return keyScope, account, err
+}
+
 // RenameAccount sets the name for an account number to newName.
 func (w *Wallet) RenameAccount(scope waddrmgr.KeyScope, account uint32, newName string) error {
 	manager, err := w.Manager.FetchScopedKeyManager(scope)