refactor: download function to be reusable (#740)

packages/lib/client-only/download-pdf.ts

@@ -0,0 +1,29 @@
+import type { DocumentData } from '@documenso/prisma/client';
+
+import { getFile } from '../universal/upload/get-file';
+
+type DownloadPDFProps = {
+  documentData: DocumentData;
+  fileName?: string;
+};
+
+export const downloadPDF = async ({ documentData, fileName }: DownloadPDFProps) => {
+  const bytes = await getFile(documentData);
+
+  const blob = new Blob([bytes], {
+    type: 'application/pdf',
+  });
+
+  const link = window.document.createElement('a');
+
+  const [baseTitle] = fileName?.includes('.pdf')
+    ? fileName.split('.pdf')
+    : [fileName ?? 'document'];
+
+  link.href = window.URL.createObjectURL(blob);
+  link.download = `${baseTitle}_signed.pdf`;
+
+  link.click();
+
+  window.URL.revokeObjectURL(link.href);
+};