action: return invalid argument on wrong index (#2271)

This catches the user error trying to set actuator 0 when it should
start at 1. And also adds a note in the docstring about it.

Signed-off-by: Julian Oes <julian@oes.ch>

src/mavsdk/plugins/action/action.cpp

@@ -297,6 +297,8 @@ std::ostream& operator<<(std::ostream& str, Action::Result const& result)
             return str << "Unsupported";
         case Action::Result::Failed:
             return str << "Failed";
+        case Action::Result::InvalidArgument:
+            return str << "Invalid Argument";
         default:
             return str << "Unknown";
     }

src/mavsdk/plugins/action/action_impl.cpp

@@ -555,6 +555,13 @@ void ActionImpl::set_actuator_async(
                     break;
             }
             command.params.maybe_param7 = static_cast<float>(zero_based_index) / 6.0f;
+        } else {
+            if (callback) {
+                _system_impl->call_user_callback([temp_callback = callback]() {
+                    temp_callback(Action::Result::InvalidArgument);
+                });
+            }
+            return;
         }
     }
 

src/mavsdk/plugins/action/include/plugins/action/action.h

@@ -97,6 +97,7 @@ class Action : public PluginBase {
         ParameterError, /**< @brief Error getting or setting parameter. */
         Unsupported, /**< @brief Action not supported. */
         Failed, /**< @brief Action failed. */
+        InvalidArgument, /**< @brief Invalid argument. */
     };
 
     /**
@@ -411,13 +412,17 @@ class Action : public PluginBase {
     /**
      * @brief Send command to set the value of an actuator.
      *
+     * Note that the index of the actuator starts at 1 and that the value goes from -1 to 1.
+     *
      * This function is non-blocking. See 'set_actuator' for the blocking counterpart.
      */
     void set_actuator_async(int32_t index, float value, const ResultCallback callback);
 
     /**
      * @brief Send command to set the value of an actuator.
      *
+     * Note that the index of the actuator starts at 1 and that the value goes from -1 to 1.
+     *
      * This function is blocking. See 'set_actuator_async' for the non-blocking counterpart.
      *
      * @return Result of request.

src/mavsdk_server/src/plugins/action/action_service_impl.h

@@ -118,6 +118,8 @@ class ActionServiceImpl final : public rpc::action::ActionService::Service {
                 return rpc::action::ActionResult_Result_RESULT_UNSUPPORTED;
             case mavsdk::Action::Result::Failed:
                 return rpc::action::ActionResult_Result_RESULT_FAILED;
+            case mavsdk::Action::Result::InvalidArgument:
+                return rpc::action::ActionResult_Result_RESULT_INVALID_ARGUMENT;
         }
     }
 
@@ -156,6 +158,8 @@ class ActionServiceImpl final : public rpc::action::ActionService::Service {
                 return mavsdk::Action::Result::Unsupported;
             case rpc::action::ActionResult_Result_RESULT_FAILED:
                 return mavsdk::Action::Result::Failed;
+            case rpc::action::ActionResult_Result_RESULT_INVALID_ARGUMENT:
+                return mavsdk::Action::Result::InvalidArgument;
         }
     }