feat: download document via api v2 (#1918)

adds document download functionality to the API v2, returning
pre-signed S3 URLs that provide secure, time-limited access to document
files similar to what happens in the API v1 download document endpoint.

packages/trpc/server/document-router/download-document.ts

@@ -0,0 +1,93 @@
+import { DocumentDataType } from '@prisma/client';
+
+import { AppError, AppErrorCode } from '@documenso/lib/errors/app-error';
+import { getDocumentById } from '@documenso/lib/server-only/document/get-document-by-id';
+import { getPresignGetUrl } from '@documenso/lib/universal/upload/server-actions';
+import { isDocumentCompleted } from '@documenso/lib/utils/document';
+
+import { authenticatedProcedure } from '../trpc';
+import { ZDownloadDocumentRequestSchema, ZDownloadDocumentResponseSchema } from './schema';
+
+export const downloadDocumentRoute = authenticatedProcedure
+  .meta({
+    openapi: {
+      method: 'GET',
+      path: '/document/{documentId}/download-beta',
+      summary: 'Download document (beta)',
+      description: 'Get a pre-signed download URL for the original or signed version of a document',
+      tags: ['Document'],
+    },
+  })
+  .input(ZDownloadDocumentRequestSchema)
+  .output(ZDownloadDocumentResponseSchema)
+  .query(async ({ input, ctx }) => {
+    const { teamId, user } = ctx;
+    const { documentId, version } = input;
+
+    ctx.logger.info({
+      input: {
+        documentId,
+        version,
+      },
+    });
+
+    if (process.env.NEXT_PUBLIC_UPLOAD_TRANSPORT !== 's3') {
+      throw new AppError(AppErrorCode.INVALID_REQUEST, {
+        message: 'Document downloads are only available when S3 storage is configured.',
+      });
+    }
+
+    const document = await getDocumentById({
+      documentId,
+      userId: user.id,
+      teamId,
+    });
+
+    if (!document.documentData) {
+      throw new AppError(AppErrorCode.NOT_FOUND, {
+        message: 'Document data not found',
+      });
+    }
+
+    if (document.documentData.type !== DocumentDataType.S3_PATH) {
+      throw new AppError(AppErrorCode.INVALID_REQUEST, {
+        message: 'Document is not stored in S3 and cannot be downloaded via URL.',
+      });
+    }
+
+    if (version === 'signed' && !isDocumentCompleted(document.status)) {
+      throw new AppError(AppErrorCode.INVALID_REQUEST, {
+        message: 'Document is not completed yet.',
+      });
+    }
+
+    try {
+      const documentData =
+        version === 'original'
+          ? document.documentData.initialData || document.documentData.data
+          : document.documentData.data;
+
+      const { url } = await getPresignGetUrl(documentData);
+
+      const baseTitle = document.title.replace(/\.pdf$/, '');
+      const suffix = version === 'signed' ? '_signed.pdf' : '.pdf';
+      const filename = `${baseTitle}${suffix}`;
+
+      return {
+        downloadUrl: url,
+        filename,
+        contentType: 'application/pdf',
+      };
+    } catch (error) {
+      ctx.logger.error({
+        error,
+        message: 'Failed to generate download URL',
+        documentId,
+        version,
+      });
+
+      throw new AppError(AppErrorCode.UNKNOWN_ERROR, {
+        message: 'Failed to generate download URL',
+      });
+    }
+  });