feat: add envelopes api (#2105)

apps/remix/server/api/files/files.helpers.ts

@@ -0,0 +1,81 @@
+import { type DocumentDataType, DocumentStatus } from '@prisma/client';
+import { type Context } from 'hono';
+
+import { sha256 } from '@documenso/lib/universal/crypto';
+import { getFileServerSide } from '@documenso/lib/universal/upload/get-file.server';
+
+import type { HonoEnv } from '../../router';
+
+type HandleEnvelopeItemFileRequestOptions = {
+  title: string;
+  status: DocumentStatus;
+  documentData: {
+    type: DocumentDataType;
+    data: string;
+    initialData: string;
+  };
+  version: 'signed' | 'original';
+  isDownload: boolean;
+  context: Context<HonoEnv>;
+};
+
+/**
+ * Helper function to handle envelope item file requests (both view and download)
+ */
+export const handleEnvelopeItemFileRequest = async ({
+  title,
+  status,
+  documentData,
+  version,
+  isDownload,
+  context: c,
+}: HandleEnvelopeItemFileRequestOptions) => {
+  const documentDataToUse = version === 'signed' ? documentData.data : documentData.initialData;
+
+  const etag = Buffer.from(sha256(documentDataToUse)).toString('hex');
+
+  if (c.req.header('If-None-Match') === etag) {
+    return c.body(null, 304);
+  }
+
+  const file = await getFileServerSide({
+    type: documentData.type,
+    data: documentDataToUse,
+  }).catch((error) => {
+    console.error(error);
+
+    return null;
+  });
+
+  if (!file) {
+    return c.json({ error: 'File not found' }, 404);
+  }
+
+  c.header('Content-Type', 'application/pdf');
+  c.header('ETag', etag);
+
+  if (!isDownload) {
+    if (status === DocumentStatus.COMPLETED) {
+      c.header('Cache-Control', 'public, max-age=31536000, immutable');
+    } else {
+      // Set a tiny 1 minute cache, with must-revalidate to ensure the client always checks for updates.
+      c.header('Cache-Control', 'public, max-age=60, must-revalidate');
+    }
+  }
+
+  if (isDownload) {
+    // Generate filename following the pattern from envelope-download-dialog.tsx
+    const baseTitle = title.replace(/\.pdf$/, '');
+    const suffix = version === 'signed' ? '_signed.pdf' : '.pdf';
+    const filename = `${baseTitle}${suffix}`;
+
+    c.header('Content-Disposition', `attachment; filename="${filename}"`);
+
+    // For downloads, prevent caching to ensure fresh data
+    c.header('Cache-Control', 'no-cache, no-store, must-revalidate');
+    c.header('Pragma', 'no-cache');
+    c.header('Expires', '0');
+  }
+
+  return c.body(file);
+};