Add audio asset handling and import command

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

@@ -0,0 +1,46 @@
+import { createOpaqueId } from "../core/ids";
+import { cloneProjectAssetRecord, type AudioAssetRecord } from "../assets/project-assets";
+
+import type { EditorCommand } from "./command";
+
+interface ImportAudioAssetCommandOptions {
+  asset: AudioAssetRecord;
+  label?: string;
+}
+
+export function createImportAudioAssetCommand(options: ImportAudioAssetCommandOptions): EditorCommand {
+  const nextAsset = cloneProjectAssetRecord(options.asset);
+
+  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.`);
+      }
+
+      context.setDocument({
+        ...currentDocument,
+        assets: {
+          ...currentDocument.assets,
+          [nextAsset.id]: cloneProjectAssetRecord(nextAsset)
+        }
+      });
+    },
+    undo(context) {
+      const currentDocument = context.getDocument();
+      const nextAssets = {
+        ...currentDocument.assets
+      };
+
+      delete nextAssets[nextAsset.id];
+
+      context.setDocument({
+        ...currentDocument,
+        assets: nextAssets
+      });
+    }
+  };
+}