add balance api

mobile/control/refill.php

@@ -1,5 +1,7 @@
 <?php
 
+use refill\CalcMerchantPrice;
+
 require_once(BASE_ROOT_PATH . '/mobile/control/merchant.php');
 require_once(BASE_HELPER_PATH . '/refill/RefillFactory.php');
 require_once(BASE_HELPER_PATH . '/mtopcard/mtopcard.php');
@@ -94,6 +96,13 @@ class refillControl extends merchantControl
             return self::outerr($code,$err);
         }
     }
+    public function balanceOp()
+    {
+        $uid = $this->adminid();
+        $minfo = new member_info($uid);
+        $available = $minfo->available_predeposit();
+        return self::outsuccess(['balance' => $available]);
+    }
 
     public function query_tradeOp()
     {