Add GLTF model import and related assets

src/commands/import-model-asset-command.ts

@@ -0,0 +1,92 @@
+import { createOpaqueId } from "../core/ids";
+import { cloneEditorSelection, type EditorSelection } from "../core/selection";
+import type { ToolMode } from "../core/tool-mode";
+import { cloneModelInstance, type ModelInstance } from "../assets/model-instances";
+import { cloneProjectAssetRecord, type ModelAssetRecord } from "../assets/project-assets";
+
+import type { EditorCommand } from "./command";
+
+interface ImportModelAssetCommandOptions {
+  asset: ModelAssetRecord;
+  modelInstance: ModelInstance;
+  label?: string;
+}
+
+function setSingleModelInstanceSelection(modelInstanceId: string): EditorSelection {
+  return {
+    kind: "modelInstances",
+    ids: [modelInstanceId]
+  };
+}
+
+export function createImportModelAssetCommand(options: ImportModelAssetCommandOptions): EditorCommand {
+  const nextAsset = cloneProjectAssetRecord(options.asset);
+  const nextModelInstance = cloneModelInstance(options.modelInstance);
+  let previousSelection: EditorSelection | null = null;
+  let previousToolMode: ToolMode | null = null;
+
+  return {
+    id: createOpaqueId("command"),
+    label: options.label ?? `Import ${nextAsset.sourceName}`,
+    execute(context) {
+      const currentDocument = context.getDocument();
+
+      if (currentDocument.assets[nextAsset.id] !== undefined) {
+        throw new Error(`Asset ${nextAsset.id} already exists.`);
+      }
+
+      if (currentDocument.modelInstances[nextModelInstance.id] !== undefined) {
+        throw new Error(`Model instance ${nextModelInstance.id} already exists.`);
+      }
+
+      if (previousSelection === null) {
+        previousSelection = cloneEditorSelection(context.getSelection());
+      }
+
+      if (previousToolMode === null) {
+        previousToolMode = context.getToolMode();
+      }
+
+      context.setDocument({
+        ...currentDocument,
+        assets: {
+          ...currentDocument.assets,
+          [nextAsset.id]: cloneProjectAssetRecord(nextAsset)
+        },
+        modelInstances: {
+          ...currentDocument.modelInstances,
+          [nextModelInstance.id]: cloneModelInstance(nextModelInstance)
+        }
+      });
+      context.setSelection(setSingleModelInstanceSelection(nextModelInstance.id));
+      context.setToolMode("select");
+    },
+    undo(context) {
+      const currentDocument = context.getDocument();
+      const nextAssets = {
+        ...currentDocument.assets
+      };
+      const nextModelInstances = {
+        ...currentDocument.modelInstances
+      };
+
+      delete nextAssets[nextAsset.id];
+      delete nextModelInstances[nextModelInstance.id];
+
+      context.setDocument({
+        ...currentDocument,
+        assets: nextAssets,
+        modelInstances: nextModelInstances
+      });
+
+      if (previousSelection !== null) {
+        context.setSelection(previousSelection);
+      }
+
+      if (previousToolMode !== null) {
+        context.setToolMode(previousToolMode);
+      }
+    }
+  };
+}
+