media: add attachment view, unify types

src/views/attachment.ts

@@ -0,0 +1,34 @@
+import { UnattachedMedia } from '@/db/unattached-media.ts';
+import { type TypeFest } from '@/deps.ts';
+
+type DittoAttachment = TypeFest.SetOptional<UnattachedMedia, 'id' | 'pubkey' | 'uploaded_at'>;
+
+function renderAttachment(media: DittoAttachment) {
+  const { id, data, url } = media;
+  return {
+    id: id ?? url ?? data.cid,
+    type: getAttachmentType(data.mime ?? ''),
+    url,
+    preview_url: url,
+    remote_url: null,
+    description: data.description ?? '',
+    blurhash: data.blurhash || null,
+    cid: data.cid,
+  };
+}
+
+/** MIME to Mastodon API `Attachment` type. */
+function getAttachmentType(mime: string): string {
+  const [type] = mime.split('/');
+
+  switch (type) {
+    case 'image':
+    case 'video':
+    case 'audio':
+      return type;
+    default:
+      return 'unknown';
+  }
+}
+
+export { type DittoAttachment, renderAttachment };