move the placement rules and the config-dependent queries off BuildingSystem

src/lib/sim/FactoryQueries.h

@@ -8,15 +8,19 @@
 #include "Building.h"
 #include "BuildingId.h"
 #include "BuildingType.h"
+#include "BeltSystem.h"
 #include "FactoryState.h"
+#include "GameConfig.h"
+#include "Port.h"
 
 // Queries and operations over the factory's world data that need nothing but that
 // data — no config, no belts, no RNG. Free functions rather than BuildingSystem
 // methods so that callers depend on the data they read instead of on the system
 // that happens to tick it (see FactoryState.h).
 //
-// A helper belongs here only if it is a pure function of FactoryState. Anything
-// needing GameConfig or the asteroid bound stays on BuildingSystem for now.
+// Most need nothing but the state. The two at the bottom also take the config,
+// because answering them means reading a building definition — but still no belts,
+// no RNG and no system.
 
 // The building with the given id, or nullptr when no building has it. Construction
 // sites are not buildings yet — use findSite for those.
@@ -52,3 +56,16 @@ const Building* findNearestBuilding(const FactoryState& state, QVector2D worldPo
 // (REQ-BLD-DECON-QUEUE), or its holding capacity is already taken — emerging
 // scrap counts against that capacity (REQ-MAT-OUTPUT-EMERGE).
 bool deliverScrapToSalvageBay(FactoryState& state, BuildingId bayId);
+
+// Every belt-facing edge of the building or site with this id (REQ-MAT-INPUT-PORTS,
+// REQ-BLD-BELT-DRAG). Empty when the id is unknown. A site has no stored ports, so
+// they are derived from its surface mask.
+std::vector<Port> getInputPorts(const FactoryState& state, const GameConfig& config,
+                                BuildingId id);
+
+// The two output directions and stored filters of a queued Splitter site
+// (REQ-BLD-SITE-CONFIG), or nullopt if the id is not one. Operational splitters are
+// configured through BeltSystem by tile instead.
+std::optional<BeltSystem::SplitterInfo> getSiteSplitterInfo(const FactoryState& state,
+                                                            const GameConfig& config,
+                                                            BuildingId id);