Improve offsite payment checks

app/Ninja/PaymentDrivers/BasePaymentDriver.php

@@ -715,6 +715,18 @@ class BasePaymentDriver
             }
         }
 
+        // check invoice still has balance
+        if ( ! $this->invoice()->balance) {
+            throw new Exception(trans('texts.payment_error_code', ['code' => 'NB']));
+        }
+
+        // check this isn't a duplicate transaction reference
+        if (Payment::whereAccountId($this->invitation->account_id)
+                ->whereTransactionReference($ref)
+                ->first()) {
+            throw new Exception(trans('texts.payment_error_code', ['code' => 'DT']));
+        }
+
         return $this->createPayment($ref);
     }
 

resources/lang/en/texts.php

@@ -2040,6 +2040,8 @@ $LANG = array(
     'enable_buy_now_buttons_help' => 'Enable support for buy now buttons',
     'changes_take_effect_immediately' => 'Note: changes take effect immediately',
     'wepay_account_description' => 'Payment gateway for Invoice Ninja',
+    'payment_error_code' => 'There was an error processing your payment [:code]. Please try again later.',
+
 
 );