Feat: Implement foliage layer management commands (create, delete, update)

src/commands/delete-foliage-layer-command.ts

@@ -0,0 +1,53 @@
+import { createOpaqueId } from "../core/ids";
+import { cloneFoliageLayer, type FoliageLayer } from "../foliage/foliage";
+
+import type { EditorCommand } from "./command";
+
+export function createDeleteFoliageLayerCommand(
+  foliageLayerId: string
+): EditorCommand {
+  let deletedLayer: FoliageLayer | null = null;
+
+  return {
+    id: createOpaqueId("command"),
+    label: "Delete foliage layer",
+    execute(context) {
+      const currentDocument = context.getDocument();
+      const currentLayer = currentDocument.foliageLayers[foliageLayerId];
+
+      if (currentLayer === undefined) {
+        throw new Error(`Foliage layer ${foliageLayerId} does not exist.`);
+      }
+
+      if (deletedLayer === null) {
+        deletedLayer = cloneFoliageLayer(currentLayer);
+      }
+
+      const nextFoliageLayers = {
+        ...currentDocument.foliageLayers
+      };
+
+      delete nextFoliageLayers[foliageLayerId];
+
+      context.setDocument({
+        ...currentDocument,
+        foliageLayers: nextFoliageLayers
+      });
+    },
+    undo(context) {
+      if (deletedLayer === null) {
+        return;
+      }
+
+      const currentDocument = context.getDocument();
+
+      context.setDocument({
+        ...currentDocument,
+        foliageLayers: {
+          ...currentDocument.foliageLayers,
+          [deletedLayer.id]: cloneFoliageLayer(deletedLayer)
+        }
+      });
+    }
+  };
+}