Show specific reason why vehicle cannot be ordered to a particular station

src/vehicle.cpp

@@ -4338,6 +4338,55 @@ bool CanVehicleUseStation(const Vehicle *v, const Station *st)
 	return CanVehicleUseStation(v->engine_type, st);
 }
 
+/**
+ * Get reason string why this station can't be used by the given vehicle
+ * @param v the vehicle to test
+ * @param st the station to test for
+ * @return true if and only if the vehicle can use this station.
+ */
+StringID GetVehicleCannotUseStationReason(const Vehicle *v, const Station *st)
+{
+	switch (v->type) {
+		case VEH_TRAIN:
+			return STR_ERROR_NO_RAIL_STATION;
+
+		case VEH_ROAD: {
+			const RoadVehicle *rv = RoadVehicle::From(v);
+			RoadStop *rs = st->GetPrimaryRoadStop(rv->IsBus() ? ROADSTOP_BUS : ROADSTOP_TRUCK);
+
+			StringID err = rv->IsBus() ? STR_ERROR_NO_BUS_STATION : STR_ERROR_NO_TRUCK_STATION;
+
+			for (; rs != nullptr; rs = rs->next) {
+				/* The vehicle is articulated and can therefore not go to a standard road stop. */
+				if (IsStandardRoadStopTile(rs->xy) && rv->HasArticulatedPart()) {
+					err = STR_ERROR_NO_STOP_ARTIC_VEH;
+					continue;
+				}
+				/* The vehicle cannot go to this roadstop (different roadtype) */
+				if (!HasTileAnyRoadType(rs->xy, rv->compatible_roadtypes)) return STR_ERROR_NO_STOP_COMPATIBLE_ROAD_TYPE;
+
+				return INVALID_STRING_ID;
+			}
+
+			return err;
+		}
+
+		case VEH_SHIP:
+			return STR_ERROR_NO_DOCK;
+
+		case VEH_AIRCRAFT:
+			if ((st->facilities & FACIL_AIRPORT) == 0) return STR_ERROR_NO_AIRPORT;
+			if (v->GetEngine()->u.air.subtype & AIR_CTOL) {
+				return STR_ERROR_AIRPORT_NO_PLANES;
+			} else {
+				return STR_ERROR_AIRPORT_NO_HELIS;
+			}
+
+		default:
+			return INVALID_STRING_ID;
+	}
+}
+
 /**
  * Access the ground vehicle cache of the vehicle.
  * @pre The vehicle is a #GroundVehicle.