Allow creating blueprints from construction sites

src/lib/sim/BuildingConfig.cpp

@@ -1,10 +1,55 @@
 #include "BuildingConfig.h"
 
+#include <algorithm>
+#include <climits>
+
 #include "BeltSystem.h"
 #include "Building.h"
 #include "BuildingSystem.h"
 #include "Simulation.h"
 
+namespace
+{
+// The blueprint-relevant geometry shared by operational buildings and construction
+// sites. Resolved from whichever of the two a selected id refers to.
+struct SelectedBuilding
+{
+    BuildingId                id;
+    BuildingType              type;
+    Rotation                  rotation;
+    QPoint                    anchor;
+    const std::vector<QPoint>* bodyCells;
+};
+
+// Resolves a selected id to a player-placeable building or construction site, if it
+// is one. Returns std::nullopt for an unknown id or a non-player-placeable building
+// (the HQ and defence stations, per REQ-UI-BLUEPRINT-CREATE).
+std::optional<SelectedBuilding> resolvePlaceable(const Simulation& sim, BuildingId id)
+{
+    const Building*         building = sim.buildings().findBuilding(id);
+    const ConstructionSite* site     = building ? nullptr : sim.buildings().findSite(id);
+    if (!building && !site)
+    {
+        return std::nullopt;
+    }
+
+    const BuildingType  type = building ? building->type : site->type;
+    const BuildingDef*  def  = sim.config().buildings.findBuildingDef(type);
+    if (!def || !def->playerPlaceable)
+    {
+        return std::nullopt;
+    }
+
+    SelectedBuilding resolved;
+    resolved.id        = id;
+    resolved.type      = type;
+    resolved.rotation  = building ? building->rotation : site->rotation;
+    resolved.anchor    = building ? building->anchor : site->anchor;
+    resolved.bodyCells = building ? &building->bodyCells : &site->bodyCells;
+    return resolved;
+}
+} // namespace
+
 std::optional<BuildingConfig> readBuildingConfig(const Simulation& sim, BuildingId id)
 {
     const Building*         building = sim.buildings().findBuilding(id);
@@ -49,3 +94,74 @@ std::optional<BuildingConfig> readBuildingConfig(const Simulation& sim, Building
 
     return config;
 }
+
+Blueprint captureBlueprintFromSelection(const Simulation&              sim,
+                                        const std::vector<BuildingId>& selectedIds)
+{
+    std::vector<SelectedBuilding> entries;
+    entries.reserve(selectedIds.size());
+    for (const BuildingId id : selectedIds)
+    {
+        const std::optional<SelectedBuilding> resolved = resolvePlaceable(sim, id);
+        if (resolved.has_value())
+        {
+            entries.push_back(*resolved);
+        }
+    }
+
+    if (entries.empty())
+    {
+        return Blueprint{};
+    }
+
+    int minX = INT_MAX, maxX = INT_MIN;
+    int minY = INT_MAX, maxY = INT_MIN;
+    for (const SelectedBuilding& e : entries)
+    {
+        for (const QPoint& cell : *e.bodyCells)
+        {
+            minX = std::min(minX, cell.x());
+            maxX = std::max(maxX, cell.x());
+            minY = std::min(minY, cell.y());
+            maxY = std::max(maxY, cell.y());
+        }
+    }
+
+    const QPoint center((minX + maxX) / 2, (minY + maxY) / 2);
+
+    Blueprint blueprint;
+    blueprint.buildings.reserve(entries.size());
+    for (const SelectedBuilding& e : entries)
+    {
+        BlueprintBuilding building;
+        building.type     = e.type;
+        building.rotation = e.rotation;
+        building.offset   = e.anchor - center;
+        // Recipe / schematic / layout / splitter-filter capture is shared with the
+        // copy-settings gesture (REQ-BLD-COPY-CONFIG) via readBuildingConfig, which
+        // handles operational buildings and construction sites alike.
+        const std::optional<BuildingConfig> config = readBuildingConfig(sim, e.id);
+        if (config.has_value())
+        {
+            building.recipeId        = config->recipeId.value_or(std::string());
+            building.shipLayout      = config->shipLayout;
+            building.splitterFilterA = config->splitterFilterA;
+            building.splitterFilterB = config->splitterFilterB;
+        }
+        blueprint.buildings.push_back(building);
+    }
+    return blueprint;
+}
+
+bool selectionHasPlaceableBuilding(const Simulation&              sim,
+                                   const std::vector<BuildingId>& selectedIds)
+{
+    for (const BuildingId id : selectedIds)
+    {
+        if (resolvePlaceable(sim, id).has_value())
+        {
+            return true;
+        }
+    }
+    return false;
+}