refactor: optimize AccountBalance

rosetta/services/account.go

@@ -59,9 +59,9 @@ func (s *AccountAPI) AccountBalance(
 	if request.AccountIdentifier.SubAccount != nil {
 		subAccount := request.AccountIdentifier.SubAccount
 		ty, exist := subAccount.Metadata["type"]
-
-		// delegated balance
-		if exist && ty.(string) == Delegation {
+		if exist {
+			switch ty.(string) {
+			case Delegation:
 				validatorAddr := subAccount.Address
 				validators, delegations := s.hmy.GetDelegationsByDelegatorByBlock(addr, block)
 				for index, validator := range validators {
@@ -69,8 +69,7 @@ func (s *AccountAPI) AccountBalance(
 						balance = new(big.Int).Add(balance, delegations[index].Amount)
 					}
 				}
-			// pending undelegated balance
-		} else if exist && ty.(string) == UnDelegation {
+			case UnDelegation:
 				validatorAddr := subAccount.Address
 				validators, delegations := s.hmy.GetDelegationsByDelegatorByBlock(addr, block)
 				for index, validator := range validators {
@@ -81,11 +80,17 @@ func (s *AccountAPI) AccountBalance(
 						}
 					}
 				}
-		} else {
+			default:
 				return nil, common.NewError(common.SanityCheckError, map[string]interface{}{
-				"message": "invalid sub account or type",
+					"message": "invalid sub account type",
 				})
 			}
+		}
+
+		return nil, common.NewError(common.SanityCheckError, map[string]interface{}{
+			"message": "invalid sub account",
+		})
+
 	} else {
 		balance, err = s.hmy.GetBalance(ctx, addr, blockNum)
 		if err != nil {