feat(core): pdf preview (#8569)

Co-authored-by: forehalo <forehalo@gmail.com>

packages/frontend/core/src/utils/resource.ts

@@ -0,0 +1,42 @@
+import { fileTypeFromBuffer } from 'file-type';
+
+export async function resourceUrlToBlob(
+  url: string
+): Promise<Blob | undefined> {
+  const buffer = await fetch(url).then(response => response.arrayBuffer());
+
+  if (!buffer) {
+    console.warn('Could not get blob');
+    return;
+  }
+  try {
+    const type = await fileTypeFromBuffer(buffer);
+    if (!type) {
+      return;
+    }
+    const blob = new Blob([buffer], { type: type.mime });
+    return blob;
+  } catch (error) {
+    console.error('Error converting resource to blob', error);
+  }
+  return;
+}
+
+export async function downloadBlob(blob: Blob, filename: string) {
+  const blobUrl = URL.createObjectURL(blob);
+  const a = document.createElement('a');
+  a.href = blobUrl;
+  a.download = filename;
+  document.body.append(a);
+  a.click();
+  a.remove();
+  URL.revokeObjectURL(blobUrl);
+}
+
+export async function downloadResourceWithUrl(url: string, filename: string) {
+  // given input url may not have correct mime type
+  const blob = await resourceUrlToBlob(url);
+  if (!blob) return;
+
+  await downloadBlob(blob, filename);
+}