Feature: Contextual actions for vehicles grouped by shared orders (#8425)

src/order_gui.cpp

@@ -29,6 +29,9 @@
 #include "aircraft.h"
 #include "engine_func.h"
 #include "vehicle_func.h"
+#include "vehiclelist.h"
+#include "vehicle_func.h"
+#include "error.h"
 #include "order_cmd.h"
 #include "company_cmd.h"
 
@@ -1466,6 +1469,40 @@ public:
 		return true;
 	}
 
+	/**
+	 * Clones an order list from a vehicle list.  If this doesn't make sense (because not all vehicles in the list have the same orders), then it displays an error.
+	 * @return This always returns true, which indicates that the contextual action handled the mouse click.
+	 *         Note that it's correct behaviour to always handle the click even though an error is displayed,
+	 *         because users aren't going to expect the default action to be performed just because they overlooked that cloning doesn't make sense.
+	 */
+	bool OnVehicleSelect(VehicleList::const_iterator begin, VehicleList::const_iterator end) override
+	{
+		bool share_order = _ctrl_pressed || this->goto_type == OPOS_SHARE;
+		if (this->vehicle->GetNumOrders() != 0 && !share_order) return false;
+
+		if (!share_order) {
+			/* If CTRL is not pressed: If all the vehicles in this list have the same orders, then copy orders */
+			if (AllEqual(begin, end, [](const Vehicle *v1, const Vehicle *v2) {
+				return VehiclesHaveSameOrderList(v1, v2);
+			})) {
+				OnVehicleSelect(*begin);
+			} else {
+				ShowErrorMessage(STR_ERROR_CAN_T_COPY_ORDER_LIST, STR_ERROR_CAN_T_COPY_ORDER_VEHICLE_LIST, WL_INFO);
+			}
+		} else {
+			/* If CTRL is pressed: If all the vehicles in this list share orders, then copy orders */
+			if (AllEqual(begin, end, [](const Vehicle *v1, const Vehicle *v2) {
+				return v1->FirstShared() == v2->FirstShared();
+			})) {
+				OnVehicleSelect(*begin);
+			} else {
+				ShowErrorMessage(STR_ERROR_CAN_T_SHARE_ORDER_LIST, STR_ERROR_CAN_T_SHARE_ORDER_VEHICLE_LIST, WL_INFO);
+			}
+		}
+
+		return true;
+	}
+
 	void OnPlaceObjectAbort() override
 	{
 		this->goto_type = OPOS_NONE;