(svn r20531) -Codechange: unify quite a bit of the vehicle building commands

7 files changed, 154 insertions, 230 deletions

diff --git a/src/aircraft_cmd.cpp b/src/aircraft_cmd.cpp
index 1c8b7e360..fe1f62113 100644
--- a/src/aircraft_cmd.cpp
+++ b/src/aircraft_cmd.cpp
@@ -215,48 +215,25 @@ void GetAircraftSpriteSize(EngineID engine, uint &width, uint &height)
 
 /**
  * Build an aircraft.
- * @param tile tile of depot where aircraft is built
- * @param flags for command
- * @param p1 aircraft type being built (engine)
- * @param p2 unused
- * @param text unused
- * @return the cost of this operation or an error
+ * @param tile     tile of the depot where aircraft is built.
+ * @param flags    type of operation.
+ * @param e        the engine to build.
+ * @param data     unused.
+ * @param ret[out] the vehicle that has been built.
+ * @return the cost of this operation or an error.
  */
-CommandCost CmdBuildAircraft(TileIndex tile, DoCommandFlag flags, uint32 p1, uint32 p2, const char *text)
+CommandCost CmdBuildAircraft(TileIndex tile, DoCommandFlag flags, const Engine *e, uint16 data, Vehicle **ret)
 {
-	EngineID eid = GB(p1, 0, 16);
-	if (!IsEngineBuildable(eid, VEH_AIRCRAFT, _current_company)) return_cmd_error(STR_ERROR_AIRCRAFT_NOT_AVAILABLE);
-
-	const Engine *e = Engine::Get(eid);
 	const AircraftVehicleInfo *avi = &e->u.air;
-	CommandCost value(EXPENSES_NEW_VEHICLES, e->GetCost());
-
-	/* Engines without valid cargo should not be available */
-	if (e->GetDefaultCargoType() == CT_INVALID) return CMD_ERROR;
-
-	/* to just query the cost, it is not neccessary to have a valid tile (automation/AI) */
-	if (flags & DC_QUERY_COST) return value;
-
-	if (!IsHangarTile(tile) || !IsTileOwner(tile, _current_company)) return CMD_ERROR;
 
 	/* Prevent building aircraft types at places which can't handle them */
-	if (!CanVehicleUseStation(eid, Station::GetByTile(tile))) return CMD_ERROR;
-
-	/* We will need to allocate 2 or 3 vehicle structs, depending on type */
-	if (!Vehicle::CanAllocateItem(avi->subtype & AIR_CTOL ? 2 : 3)) {
-		return_cmd_error(STR_ERROR_TOO_MANY_VEHICLES_IN_GAME);
-	}
-
-	UnitID unit_num = (flags & DC_AUTOREPLACE) ? 0 : GetFreeUnitNumber(VEH_AIRCRAFT);
-	if (unit_num > _settings_game.vehicle.max_aircraft) {
-		return_cmd_error(STR_ERROR_TOO_MANY_VEHICLES_IN_GAME);
-	}
+	if (!CanVehicleUseStation(e->index, Station::GetByTile(tile))) return CMD_ERROR;
 
 	if (flags & DC_EXEC) {
 		Aircraft *v = new Aircraft(); // aircraft
 		Aircraft *u = new Aircraft(); // shadow
+		*ret = v;
 
-		v->unitnumber = unit_num;
 		v->direction = DIR_SE;
 
 		v->owner = u->owner = _current_company;
@@ -288,12 +265,11 @@ CommandCost CmdBuildAircraft(TileIndex tile, DoCommandFlag flags, uint32 p1, uin
 
 		v->max_speed = avi->max_speed;
 		v->acceleration = avi->acceleration;
-		v->engine_type = eid;
-		u->engine_type = eid;
+		v->engine_type = e->index;
+		u->engine_type = e->index;
 
 		v->subtype = (avi->subtype & AIR_CTOL ? AIR_AIRCRAFT : AIR_HELICOPTER);
 		v->UpdateDeltaXY(INVALID_DIR);
-		v->value = value.GetCost();
 
 		u->subtype = AIR_SHADOW;
 		u->UpdateDeltaXY(INVALID_DIR);
@@ -338,7 +314,7 @@ CommandCost CmdBuildAircraft(TileIndex tile, DoCommandFlag flags, uint32 p1, uin
 		/* Aircraft with 3 vehicles (chopper)? */
 		if (v->subtype == AIR_HELICOPTER) {
 			Aircraft *w = new Aircraft();
-			w->engine_type = eid;
+			w->engine_type = e->index;
 			w->direction = DIR_N;
 			w->owner = _current_company;
 			w->x_pos = v->x_pos;
@@ -356,18 +332,9 @@ CommandCost CmdBuildAircraft(TileIndex tile, DoCommandFlag flags, uint32 p1, uin
 			u->SetNext(w);
 			VehicleMove(w, false);
 		}
-
-		InvalidateWindowData(WC_VEHICLE_DEPOT, v->tile);
-		InvalidateWindowClassesData(WC_AIRCRAFT_LIST, 0);
-		SetWindowDirty(WC_COMPANY, v->owner);
-		if (IsLocalCompany()) {
-			InvalidateAutoreplaceWindow(v->engine_type, v->group_id); // updates the replace Aircraft window
-		}
-
-		Company::Get(_current_company)->num_engines[eid]++;
 	}
 
-	return value;
+	return CommandCost();
 }
 
 
diff --git a/src/command.cpp b/src/command.cpp
index 31d70be88..ac4d56aed 100644
--- a/src/command.cpp
+++ b/src/command.cpp
@@ -77,9 +77,9 @@ CommandProc CmdBuildBuoy;
 
 CommandProc CmdPlantTree;
 
-CommandProc CmdBuildRailVehicle;
 CommandProc CmdMoveRailVehicle;
 
+CommandProc CmdBuildVehicle;
 CommandProc CmdSellRailWagon;
 
 CommandProc CmdSendTrainToDepot;
@@ -113,14 +113,12 @@ CommandProc CmdRenameStation;
 CommandProc CmdRenameDepot;
 
 CommandProc CmdSellAircraft;
-CommandProc CmdBuildAircraft;
 CommandProc CmdSendAircraftToHangar;
 CommandProc CmdRefitAircraft;
 
 CommandProc CmdPlaceSign;
 CommandProc CmdRenameSign;
 
-CommandProc CmdBuildRoadVeh;
 CommandProc CmdSellRoadVeh;
 CommandProc CmdSendRoadVehToDepot;
 CommandProc CmdTurnRoadVeh;
@@ -142,7 +140,6 @@ CommandProc CmdChangeSetting;
 CommandProc CmdChangeCompanySetting;
 
 CommandProc CmdSellShip;
-CommandProc CmdBuildShip;
 CommandProc CmdSendShipToDepot;
 CommandProc CmdRefitShip;
 
@@ -229,7 +226,7 @@ static const Command _command_proc_table[] = {
 	DEF_CMD(CmdBuildShipDepot,                          CMD_AUTO), // CMD_BUILD_SHIP_DEPOT
 	DEF_CMD(CmdBuildBuoy,                               CMD_AUTO), // CMD_BUILD_BUOY
 	DEF_CMD(CmdPlantTree,                               CMD_AUTO), // CMD_PLANT_TREE
-	DEF_CMD(CmdBuildRailVehicle,                               0), // CMD_BUILD_RAIL_VEHICLE
+	DEF_CMD(CmdBuildVehicle,                                   0), // CMD_BUILD_VEHICLE
 	DEF_CMD(CmdMoveRailVehicle,                                0), // CMD_MOVE_RAIL_VEHICLE
 
 	DEF_CMD(CmdSellRailWagon,                                  0), // CMD_SELL_RAIL_WAGON
@@ -264,14 +261,12 @@ static const Command _command_proc_table[] = {
 
 	DEF_CMD(CmdSellAircraft,                                   0), // CMD_SELL_AIRCRAFT
 
-	DEF_CMD(CmdBuildAircraft,                                  0), // CMD_BUILD_AIRCRAFT
 	DEF_CMD(CmdSendAircraftToHangar,                           0), // CMD_SEND_AIRCRAFT_TO_HANGAR
 	DEF_CMD(CmdRefitAircraft,                                  0), // CMD_REFIT_AIRCRAFT
 
 	DEF_CMD(CmdPlaceSign,                                      0), // CMD_PLACE_SIGN
 	DEF_CMD(CmdRenameSign,                                     0), // CMD_RENAME_SIGN
 
-	DEF_CMD(CmdBuildRoadVeh,                                   0), // CMD_BUILD_ROAD_VEH
 	DEF_CMD(CmdSellRoadVeh,                                    0), // CMD_SELL_ROAD_VEH
 	DEF_CMD(CmdSendRoadVehToDepot,                             0), // CMD_SEND_ROADVEH_TO_DEPOT
 	DEF_CMD(CmdTurnRoadVeh,                                    0), // CMD_TURN_ROADVEH
@@ -290,7 +285,6 @@ static const Command _command_proc_table[] = {
 	DEF_CMD(CmdDeleteTown,                           CMD_OFFLINE), // CMD_DELETE_TOWN
 
 	DEF_CMD(CmdSellShip,                                       0), // CMD_SELL_SHIP
-	DEF_CMD(CmdBuildShip,                                      0), // CMD_BUILD_SHIP
 	DEF_CMD(CmdSendShipToDepot,                                0), // CMD_SEND_SHIP_TO_DEPOT
 	DEF_CMD(CmdRefitShip,                                      0), // CMD_REFIT_SHIP
 
diff --git a/src/command_type.h b/src/command_type.h
index be7c14441..78f6fa8eb 100644
--- a/src/command_type.h
+++ b/src/command_type.h
@@ -177,7 +177,7 @@ enum Commands {
 
 	CMD_PLANT_TREE,                   ///< plant a tree
 
-	CMD_BUILD_RAIL_VEHICLE,           ///< build a rail vehicle
+	CMD_BUILD_VEHICLE,                ///< build a vehicle
 	CMD_MOVE_RAIL_VEHICLE,            ///< move a rail vehicle (in the depot)
 
 	CMD_SELL_RAIL_WAGON,              ///< sell a rail wagon
@@ -211,14 +211,12 @@ enum Commands {
 	CMD_RENAME_DEPOT,                 ///< rename a depot
 
 	CMD_SELL_AIRCRAFT,                ///< sell an aircraft
-	CMD_BUILD_AIRCRAFT,               ///< build an aircraft
 	CMD_SEND_AIRCRAFT_TO_HANGAR,      ///< send an aircraft to a hanger
 	CMD_REFIT_AIRCRAFT,               ///< refit the cargo space of an aircraft
 
 	CMD_PLACE_SIGN,                   ///< place a sign
 	CMD_RENAME_SIGN,                  ///< rename a sign
 
-	CMD_BUILD_ROAD_VEH,               ///< build a road vehicle
 	CMD_SELL_ROAD_VEH,                ///< sell a road vehicle
 	CMD_SEND_ROADVEH_TO_DEPOT,        ///< send a road vehicle to the depot
 	CMD_TURN_ROADVEH,                 ///< turn a road vehicle around
@@ -237,7 +235,6 @@ enum Commands {
 	CMD_DELETE_TOWN,                  ///< delete a town
 
 	CMD_SELL_SHIP,                    ///< sell a ship
-	CMD_BUILD_SHIP,                   ///< build a new ship
 	CMD_SEND_SHIP_TO_DEPOT,           ///< send a ship to a depot
 	CMD_REFIT_SHIP,                   ///< refit the cargo space of a ship
 
diff --git a/src/roadveh_cmd.cpp b/src/roadveh_cmd.cpp
index b9296a866..545068583 100644
--- a/src/roadveh_cmd.cpp
+++ b/src/roadveh_cmd.cpp
@@ -202,50 +202,22 @@ void RoadVehUpdateCache(RoadVehicle *v)
 
 /**
  * Build a road vehicle.
- * @param tile tile of depot where road vehicle is built
- * @param flags operation to perform
- * @param p1 bus/truck type being built (engine)
- * @param p2 unused
- * @param text unused
- * @return the cost of this operation or an error
+ * @param tile     tile of the depot where road vehicle is built.
+ * @param flags    type of operation.
+ * @param e        the engine to build.
+ * @param data     unused.
+ * @param ret[out] the vehicle that has been built.
+ * @return the cost of this operation or an error.
  */
-CommandCost CmdBuildRoadVeh(TileIndex tile, DoCommandFlag flags, uint32 p1, uint32 p2, const char *text)
+CommandCost CmdBuildRoadVehicle(TileIndex tile, DoCommandFlag flags, const Engine *e, uint16 data, Vehicle **ret)
 {
-	EngineID eid = GB(p1, 0, 16);
-	if (!IsEngineBuildable(eid, VEH_ROAD, _current_company)) return_cmd_error(STR_ERROR_ROAD_VEHICLE_NOT_AVAILABLE);
-
-	const Engine *e = Engine::Get(eid);
-	/* Engines without valid cargo should not be available */
-	if (e->GetDefaultCargoType() == CT_INVALID) return CMD_ERROR;
-
-	CommandCost cost(EXPENSES_NEW_VEHICLES, e->GetCost());
-	if (flags & DC_QUERY_COST) return cost;
-
-	/* The ai_new queries the vehicle cost before building the route,
-	 * so we must check against cheaters no sooner than now. --pasky */
-	if (!IsRoadDepotTile(tile)) return CMD_ERROR;
-	if (!IsTileOwner(tile, _current_company)) return CMD_ERROR;
-
 	if (HasTileRoadType(tile, ROADTYPE_TRAM) != HasBit(e->info.misc_flags, EF_ROAD_TRAM)) return_cmd_error(STR_ERROR_DEPOT_WRONG_DEPOT_TYPE);
 
-	uint num_vehicles = 1 + CountArticulatedParts(eid, false);
-
-	/* Allow for the front and the articulated parts */
-	if (!Vehicle::CanAllocateItem(num_vehicles)) {
-		return_cmd_error(STR_ERROR_TOO_MANY_VEHICLES_IN_GAME);
-	}
-
-	/* find the first free roadveh id */
-	UnitID unit_num = (flags & DC_AUTOREPLACE) ? 0 : GetFreeUnitNumber(VEH_ROAD);
-	if (unit_num > _settings_game.vehicle.max_roadveh) {
-		return_cmd_error(STR_ERROR_TOO_MANY_VEHICLES_IN_GAME);
-	}
-
 	if (flags & DC_EXEC) {
 		const RoadVehicleInfo *rvi = &e->u.road;
 
 		RoadVehicle *v = new RoadVehicle();
-		v->unitnumber = unit_num;
+		*ret = v;
 		v->direction = DiagDirToDir(GetRoadDepotDirection(tile));
 		v->owner = _current_company;
 
@@ -262,11 +234,10 @@ CommandCost CmdBuildRoadVeh(TileIndex tile, DoCommandFlag flags, uint32 p1, uint
 		v->spritenum = rvi->image_index;
 		v->cargo_type = e->GetDefaultCargoType();
 		v->cargo_cap = rvi->capacity;
-		v->value = cost.GetCost();
 
 		v->last_station_visited = INVALID_STATION;
 		v->max_speed = rvi->max_speed;
-		v->engine_type = eid;
+		v->engine_type = e->index;
 		v->rcache.first_engine = INVALID_ENGINE; // needs to be set before first callback
 
 		v->reliability = e->reliability;
@@ -304,19 +275,10 @@ CommandCost CmdBuildRoadVeh(TileIndex tile, DoCommandFlag flags, uint32 p1, uint
 
 		VehicleMove(v, false);
 
-		InvalidateWindowData(WC_VEHICLE_DEPOT, v->tile);
-		InvalidateWindowClassesData(WC_ROADVEH_LIST, 0);
-		SetWindowDirty(WC_COMPANY, v->owner);
-		if (IsLocalCompany()) {
-			InvalidateAutoreplaceWindow(v->engine_type, v->group_id); // updates the replace Road window
-		}
-
-		Company::Get(_current_company)->num_engines[eid]++;
-
 		CheckConsistencyOfArticulatedVehicle(v);
 	}
 
-	return cost;
+	return CommandCost();
 }
 
 bool RoadVehicle::IsStoppedInDepot() const
diff --git a/src/ship_cmd.cpp b/src/ship_cmd.cpp
index 5ec206648..1b0bb2421 100644
--- a/src/ship_cmd.cpp
+++ b/src/ship_cmd.cpp
@@ -604,37 +604,15 @@ bool Ship::Tick()
 
 /**
  * Build a ship.
- * @param tile tile of depot where ship is built
- * @param flags type of operation
- * @param p1 ship type being built (engine)
- * @param p2 unused
- * @param text unused
- * @return the cost of this operation or an error
+ * @param tile     tile of the depot where ship is built.
+ * @param flags    type of operation.
+ * @param e        the engine to build.
+ * @param data     unused.
+ * @param ret[out] the vehicle that has been built.
+ * @return the cost of this operation or an error.
  */
-CommandCost CmdBuildShip(TileIndex tile, DoCommandFlag flags, uint32 p1, uint32 p2, const char *text)
+CommandCost CmdBuildShip(TileIndex tile, DoCommandFlag flags, const Engine *e, uint16 data, Vehicle **ret)
 {
-	EngineID eid = GB(p1, 0, 16);
-	UnitID unit_num;
-
-	if (!IsEngineBuildable(eid, VEH_SHIP, _current_company)) return_cmd_error(STR_ERROR_SHIP_NOT_AVAILABLE);
-
-	const Engine *e = Engine::Get(eid);
-	CommandCost value(EXPENSES_NEW_VEHICLES, e->GetCost());
-
-	/* Engines without valid cargo should not be available */
-	if (e->GetDefaultCargoType() == CT_INVALID) return CMD_ERROR;
-
-	if (flags & DC_QUERY_COST) return value;
-
-	/* The ai_new queries the vehicle cost before building the route,
-	 * so we must check against cheaters no sooner than now. --pasky */
-	if (!IsShipDepotTile(tile)) return CMD_ERROR;
-	if (!IsTileOwner(tile, _current_company)) return CMD_ERROR;
-
-	unit_num = (flags & DC_AUTOREPLACE) ? 0 : GetFreeUnitNumber(VEH_SHIP);
-
-	if (!Vehicle::CanAllocateItem() || unit_num > _settings_game.vehicle.max_ships) return_cmd_error(STR_ERROR_TOO_MANY_VEHICLES_IN_GAME);
-
 	if (flags & DC_EXEC) {
 		int x;
 		int y;
@@ -642,7 +620,7 @@ CommandCost CmdBuildShip(TileIndex tile, DoCommandFlag flags, uint32 p1, uint32
 		const ShipVehicleInfo *svi = &e->u.ship;
 
 		Ship *v = new Ship();
-		v->unitnumber = unit_num;
+		*ret = v;
 
 		v->owner = _current_company;
 		v->tile = tile;
@@ -658,11 +636,10 @@ CommandCost CmdBuildShip(TileIndex tile, DoCommandFlag flags, uint32 p1, uint32
 		v->spritenum = svi->image_index;
 		v->cargo_type = e->GetDefaultCargoType();
 		v->cargo_cap = svi->capacity;
-		v->value = value.GetCost();
 
 		v->last_station_visited = INVALID_STATION;
 		v->max_speed = svi->max_speed;
-		v->engine_type = eid;
+		v->engine_type = e->index;
 
 		v->reliability = e->reliability;
 		v->reliability_spd_dec = e->reliability_spd_dec;
@@ -686,18 +663,9 @@ CommandCost CmdBuildShip(TileIndex tile, DoCommandFlag flags, uint32 p1, uint32
 		v->InvalidateNewGRFCacheOfChain();
 
 		VehicleMove(v, false);
-
-		InvalidateWindowData(WC_VEHICLE_DEPOT, v->tile);
-		InvalidateWindowClassesData(WC_SHIPS_LIST, 0);
-		SetWindowDirty(WC_COMPANY, v->owner);
-		if (IsLocalCompany()) {
-			InvalidateAutoreplaceWindow(v->engine_type, v->group_id); // updates the replace Ship window
-		}
-
-		Company::Get(_current_company)->num_engines[eid]++;
 	}
 
-	return value;
+	return CommandCost();
 }
 
 /**
diff --git a/src/train_cmd.cpp b/src/train_cmd.cpp
index 70c275925..8a83755a5 100644
--- a/src/train_cmd.cpp
+++ b/src/train_cmd.cpp
@@ -574,32 +574,27 @@ void DrawTrainEngine(int left, int right, int preferred_x, int y, EngineID engin
 	}
 }
 
-static CommandCost CmdBuildRailWagon(EngineID engine, TileIndex tile, DoCommandFlag flags)
+/**
+ * Build a railroad wagon.
+ * @param tile     tile of the depot where rail-vehicle is built.
+ * @param flags    type of operation.
+ * @param e        the engine to build.
+ * @param ret[out] the vehicle that has been built.
+ * @return the cost of this operation or an error.
+ */
+CommandCost CmdBuildRailWagon(TileIndex tile, DoCommandFlag flags, const Engine *e, Vehicle **ret)
 {
-	const Engine *e = Engine::Get(engine);
 	const RailVehicleInfo *rvi = &e->u.rail;
-	CommandCost value(EXPENSES_NEW_VEHICLES, e->GetCost());
-
-	/* Engines without valid cargo should not be available */
-	if (e->GetDefaultCargoType() == CT_INVALID) return CMD_ERROR;
-
-	if (flags & DC_QUERY_COST) return value;
 
 	/* Check that the wagon can drive on the track in question */
 	if (!IsCompatibleRail(rvi->railtype, GetRailType(tile))) return CMD_ERROR;
 
-	uint num_vehicles = 1 + CountArticulatedParts(engine, false);
-
-	/* Allow for the wagon and the articulated parts */
-	if (!Vehicle::CanAllocateItem(num_vehicles)) {
-		return_cmd_error(STR_ERROR_TOO_MANY_VEHICLES_IN_GAME);
-	}
-
 	if (flags & DC_EXEC) {
 		Train *v = new Train();
+		*ret = v;
 		v->spritenum = rvi->image_index;
 
-		v->engine_type = engine;
+		v->engine_type = e->index;
 		v->tcache.first_engine = INVALID_ENGINE; // needs to be set before first callback
 
 		DiagDirection dir = GetRailDepotDirection(tile);
@@ -624,7 +619,6 @@ static CommandCost CmdBuildRailWagon(EngineID engine, TileIndex tile, DoCommandF
 
 		v->cargo_type = e->GetDefaultCargoType();
 		v->cargo_cap = rvi->capacity;
-		v->value = value.GetCost();
 
 		v->railtype = rvi->railtype;
 
@@ -642,12 +636,6 @@ static CommandCost CmdBuildRailWagon(EngineID engine, TileIndex tile, DoCommandF
 		v->First()->ConsistChanged(false);
 		UpdateTrainGroupID(v->First());
 
-		SetWindowDirty(WC_VEHICLE_DEPOT, v->tile);
-		if (IsLocalCompany()) {
-			InvalidateAutoreplaceWindow(v->engine_type, v->group_id); // updates the replace Train window
-		}
-		Company::Get(_current_company)->num_engines[engine]++;
-
 		CheckConsistencyOfArticulatedVehicle(v);
 
 		/* Try to connect the vehicle to one of free chains of wagons. */
@@ -655,7 +643,7 @@ static CommandCost CmdBuildRailWagon(EngineID engine, TileIndex tile, DoCommandF
 		FOR_ALL_TRAINS(w) {
 			if (w->tile == tile &&              ///< Same depot
 					w->IsFreeWagon() &&             ///< A free wagon chain
-					w->engine_type == engine &&     ///< Same type
+					w->engine_type == e->index &&   ///< Same type
 					w->First() != v &&              ///< Don't connect to ourself
 					!(w->vehstatus & VS_CRASHED)) { ///< Not crashed/flooded
 				DoCommand(0, v->index | (w->Last()->index << 16), 1, DC_EXEC, CMD_MOVE_RAIL_VEHICLE);
@@ -664,7 +652,7 @@ static CommandCost CmdBuildRailWagon(EngineID engine, TileIndex tile, DoCommandF
 		}
 	}
 
-	return value;
+	return CommandCost();
 }
 
 /** Move all free vehicles in the depot to the train */
@@ -715,60 +703,30 @@ static void AddRearEngineToMultiheadedTrain(Train *v)
 
 /**
  * Build a railroad vehicle.
- * @param tile tile of the depot where rail-vehicle is built
- * @param flags type of operation
- * @param p1 engine type id
- * @param p2 bit 1 prevents any free cars from being added to the train
- * @param text unused
- * @return the cost of this operation or an error
+ * @param tile     tile of the depot where rail-vehicle is built.
+ * @param flags    type of operation.
+ * @param e        the engine to build.
+ * @param data     bit 0 prevents any free cars from being added to the train.
+ * @param ret[out] the vehicle that has been built.
+ * @return the cost of this operation or an error.
  */
-CommandCost CmdBuildRailVehicle(TileIndex tile, DoCommandFlag flags, uint32 p1, uint32 p2, const char *text)
+CommandCost CmdBuildRailVehicle(TileIndex tile, DoCommandFlag flags, const Engine *e, uint16 data, Vehicle **ret)
 {
-	EngineID eid = GB(p1, 0, 16);
-	/* Check if the engine-type is valid (for the company) */
-	if (!IsEngineBuildable(eid, VEH_TRAIN, _current_company)) return_cmd_error(STR_ERROR_RAIL_VEHICLE_NOT_AVAILABLE);
-
-	const Engine *e = Engine::Get(eid);
 	const RailVehicleInfo *rvi = &e->u.rail;
-	CommandCost value(EXPENSES_NEW_VEHICLES, e->GetCost());
-
-	/* Engines with CT_INVALID should not be available */
-	if (e->GetDefaultCargoType() == CT_INVALID) return CMD_ERROR;
-
-	if (flags & DC_QUERY_COST) return value;
-
-	/* Check if the train is actually being built in a depot belonging
-	 * to the company. Doesn't matter if only the cost is queried */
-	if (!IsRailDepotTile(tile)) return CMD_ERROR;
-	if (!IsTileOwner(tile, _current_company)) return CMD_ERROR;
 
-	if (rvi->railveh_type == RAILVEH_WAGON) return CmdBuildRailWagon(eid, tile, flags);
-
-	uint num_vehicles =
-		(rvi->railveh_type == RAILVEH_MULTIHEAD ? 2 : 1) +
-		CountArticulatedParts(eid, false);
+	if (rvi->railveh_type == RAILVEH_WAGON) return CmdBuildRailWagon(tile, flags, e, ret);
 
 	/* Check if depot and new engine uses the same kind of tracks *
 	 * We need to see if the engine got power on the tile to avoid electric engines in non-electric depots */
 	if (!HasPowerOnRail(rvi->railtype, GetRailType(tile))) return CMD_ERROR;
 
-	/* Allow for the dual-heads and the articulated parts */
-	if (!Vehicle::CanAllocateItem(num_vehicles)) {
-		return_cmd_error(STR_ERROR_TOO_MANY_VEHICLES_IN_GAME);
-	}
-
-	UnitID unit_num = (flags & DC_AUTOREPLACE) ? 0 : GetFreeUnitNumber(VEH_TRAIN);
-	if (unit_num > _settings_game.vehicle.max_trains) {
-		return_cmd_error(STR_ERROR_TOO_MANY_VEHICLES_IN_GAME);
-	}
-
 	if (flags & DC_EXEC) {
 		DiagDirection dir = GetRailDepotDirection(tile);
 		int x = TileX(tile) * TILE_SIZE + _vehicle_initial_x_fract[dir];
 		int y = TileY(tile) * TILE_SIZE + _vehicle_initial_y_fract[dir];
 
 		Train *v = new Train();
-		v->unitnumber = unit_num;
+		*ret = v;
 		v->direction = DiagDirToDir(dir);
 		v->tile = tile;
 		v->owner = _current_company;
@@ -781,10 +739,9 @@ CommandCost CmdBuildRailVehicle(TileIndex tile, DoCommandFlag flags, uint32 p1,
 		v->cargo_type = e->GetDefaultCargoType();
 		v->cargo_cap = rvi->capacity;
 		v->max_speed = rvi->max_speed;
-		v->value = value.GetCost();
 		v->last_station_visited = INVALID_STATION;
 
-		v->engine_type = eid;
+		v->engine_type = e->index;
 		v->tcache.first_engine = INVALID_ENGINE; // needs to be set before first callback
 
 		v->reliability = e->reliability;
@@ -818,23 +775,14 @@ CommandCost CmdBuildRailVehicle(TileIndex tile, DoCommandFlag flags, uint32 p1,
 		v->ConsistChanged(false);
 		UpdateTrainGroupID(v);
 
-		if (!HasBit(p2, 1) && !(flags & DC_AUTOREPLACE)) { // check if the cars should be added to the new vehicle
+		if (!HasBit(data, 0) && !(flags & DC_AUTOREPLACE)) { // check if the cars should be added to the new vehicle
 			NormalizeTrainVehInDepot(v);
 		}
 
-		InvalidateWindowData(WC_VEHICLE_DEPOT, v->tile);
-		InvalidateWindowClassesData(WC_TRAINS_LIST, 0);
-		SetWindowDirty(WC_COMPANY, v->owner);
-		if (IsLocalCompany()) {
-			InvalidateAutoreplaceWindow(v->engine_type, v->group_id); // updates the replace Train window
-		}
-
-		Company::Get(_current_company)->num_engines[eid]++;
-
 		CheckConsistencyOfArticulatedVehicle(v);
 	}
 
-	return value;
+	return CommandCost();
 }
 
 
diff --git a/src/vehicle_cmd.cpp b/src/vehicle_cmd.cpp
index e63609434..b08c9406d 100644
--- a/src/vehicle_cmd.cpp
+++ b/src/vehicle_cmd.cpp
@@ -28,15 +28,19 @@
 #include "depot_map.h"
 #include "vehiclelist.h"
 #include "engine_base.h"
+#include "engine_func.h"
+#include "articulated_vehicles.h"
+#include "autoreplace_gui.h"
+#include "company_base.h"
 
 #include "table/strings.h"
 
 /* Tables used in vehicle.h to find the right command for a certain vehicle type */
 const uint32 _veh_build_proc_table[] = {
-	CMD_BUILD_RAIL_VEHICLE | CMD_MSG(STR_ERROR_CAN_T_BUY_TRAIN),
-	CMD_BUILD_ROAD_VEH     | CMD_MSG(STR_ERROR_CAN_T_BUY_ROAD_VEHICLE),
-	CMD_BUILD_SHIP         | CMD_MSG(STR_ERROR_CAN_T_BUY_SHIP),
-	CMD_BUILD_AIRCRAFT     | CMD_MSG(STR_ERROR_CAN_T_BUY_AIRCRAFT),
+	CMD_BUILD_VEHICLE | CMD_MSG(STR_ERROR_CAN_T_BUY_TRAIN),
+	CMD_BUILD_VEHICLE | CMD_MSG(STR_ERROR_CAN_T_BUY_ROAD_VEHICLE),
+	CMD_BUILD_VEHICLE | CMD_MSG(STR_ERROR_CAN_T_BUY_SHIP),
+	CMD_BUILD_VEHICLE | CMD_MSG(STR_ERROR_CAN_T_BUY_AIRCRAFT),
 };
 
 const uint32 _veh_sell_proc_table[] = {
@@ -61,6 +65,90 @@ const uint32 _send_to_depot_proc_table[] = {
 	CMD_SEND_AIRCRAFT_TO_HANGAR | CMD_MSG(STR_ERROR_CAN_T_SEND_AIRCRAFT_TO_HANGAR),
 };
 
+
+CommandCost CmdBuildRailVehicle(TileIndex tile, DoCommandFlag flags, const Engine *e, uint16 data, Vehicle **v);
+CommandCost CmdBuildRoadVehicle(TileIndex tile, DoCommandFlag flags, const Engine *e, uint16 data, Vehicle **v);
+CommandCost CmdBuildShip       (TileIndex tile, DoCommandFlag flags, const Engine *e, uint16 data, Vehicle **v);
+CommandCost CmdBuildAircraft   (TileIndex tile, DoCommandFlag flags, const Engine *e, uint16 data, Vehicle **v);
+
+/**
+ * Build a vehicle.
+ * @param tile tile of depot where the vehicle is built
+ * @param flags for command
+ * @param p1 various bitstuffed data
+ *  bits  0-15: vehicle type being built.
+ *  bits 16-31: vehicle type specific bits passed on to the vehicle build functions.
+ * @param p2 unused
+ * @param text unused
+ * @return the cost of this operation or an error
+ */
+CommandCost CmdBuildVehicle(TileIndex tile, DoCommandFlag flags, uint32 p1, uint32 p2, const char *text)
+{
+	/* Elementary check for valid location. */
+	if (!IsDepotTile(tile) || !IsTileOwner(tile, _current_company)) return CMD_ERROR;
+
+	VehicleType type;
+	switch (GetTileType(tile)) {
+		case MP_RAILWAY: type = VEH_TRAIN;    break;
+		case MP_ROAD:    type = VEH_ROAD;     break;
+		case MP_WATER:   type = VEH_SHIP;     break;
+		case MP_STATION: type = VEH_AIRCRAFT; break;
+		default: NOT_REACHED(); // Safe due to IsDepotTile()
+	}
+
+	/* Validate the engine type. */
+	EngineID eid = GB(p1, 0, 16);
+	if (!IsEngineBuildable(eid, type, _current_company)) return_cmd_error(STR_ERROR_RAIL_VEHICLE_NOT_AVAILABLE + type);
+
+	const Engine *e = Engine::Get(eid);
+	CommandCost value(EXPENSES_NEW_VEHICLES, e->GetCost());
+
+	/* Engines without valid cargo should not be available */
+	if (e->GetDefaultCargoType() == CT_INVALID) return CMD_ERROR;
+
+	/* Check whether the number of vehicles we need to build can be built according to pool space. */
+	uint num_vehicles;
+	switch (type) {
+		case VEH_TRAIN:    num_vehicles = (e->u.rail.railveh_type == RAILVEH_MULTIHEAD ? 2 : 1) + CountArticulatedParts(eid, false); break;
+		case VEH_ROAD:     num_vehicles = 1 + CountArticulatedParts(eid, false); break;
+		case VEH_SHIP:     num_vehicles = 1; break;
+		case VEH_AIRCRAFT: num_vehicles = e->u.air.subtype & AIR_CTOL ? 2 : 3; break;
+		default: NOT_REACHED(); // Safe due to IsDepotTile()
+	}
+	if (!Vehicle::CanAllocateItem(num_vehicles)) return_cmd_error(STR_ERROR_TOO_MANY_VEHICLES_IN_GAME);
+
+	/* Check whether we can allocate a unit number. Autoreplace does not allocate
+	 * an unit number as it will (always) reuse the one of the replaced vehicle
+	 * and (train) wagons don't have an unit number in any scenario. */
+	UnitID unit_num = (flags & DC_AUTOREPLACE || (type == VEH_TRAIN && e->u.rail.railveh_type == RAILVEH_WAGON)) ? 0 : GetFreeUnitNumber(type);
+	if (unit_num == UINT16_MAX) return_cmd_error(STR_ERROR_TOO_MANY_VEHICLES_IN_GAME);
+
+	Vehicle *v;
+	switch (type) {
+		case VEH_TRAIN:    value.AddCost(CmdBuildRailVehicle(tile, flags, e, GB(p1, 16, 16), &v)); break;
+		case VEH_ROAD:     value.AddCost(CmdBuildRoadVehicle(tile, flags, e, GB(p1, 16, 16), &v)); break;
+		case VEH_SHIP:     value.AddCost(CmdBuildShip       (tile, flags, e, GB(p1, 16, 16), &v)); break;
+		case VEH_AIRCRAFT: value.AddCost(CmdBuildAircraft   (tile, flags, e, GB(p1, 16, 16), &v)); break;
+		default: NOT_REACHED(); // Safe due to IsDepotTile()
+	}
+
+	if (value.Succeeded() && flags & DC_EXEC) {
+		v->unitnumber = unit_num;
+		v->value      = value.GetCost();
+
+		InvalidateWindowData(WC_VEHICLE_DEPOT, tile);
+		InvalidateWindowClassesData(GetWindowClassForVehicleType(type), 0);
+		SetWindowDirty(WC_COMPANY, _current_company);
+		if (IsLocalCompany()) {
+			InvalidateAutoreplaceWindow(v->engine_type, v->group_id); // updates the auto replace window
+		}
+
+		Company::Get(_current_company)->num_engines[eid]++;
+	}
+
+	return value;
+}
+
 /**
  * Start/Stop a vehicle
  * @param tile unused
@@ -467,7 +555,7 @@ CommandCost CmdCloneVehicle(TileIndex tile, DoCommandFlag flags, uint32 p1, uint
 		DoCommandFlag build_flags = flags;
 		if ((flags & DC_EXEC) && !v->IsPrimaryVehicle()) build_flags |= DC_AUTOREPLACE;
 
-		CommandCost cost = DoCommand(tile, v->engine_type, 2, build_flags, GetCmdBuildVeh(v));
+		CommandCost cost = DoCommand(tile, v->engine_type | (1 << 16), 0, build_flags, GetCmdBuildVeh(v));
 
 		if (cost.Failed()) {
 			/* Can't build a part, then sell the stuff we already made; clear up the mess */