feat: multisign embedding (#1823)

Adds the ability to use a multisign embedding for cases where multiple
documents need to be signed in a convenient manner.

packages/trpc/server/embedding-router/get-multi-sign-document.ts

@@ -0,0 +1,62 @@
+import { AppError, AppErrorCode } from '@documenso/lib/errors/app-error';
+import { getDocumentAndSenderByToken } from '@documenso/lib/server-only/document/get-document-by-token';
+import { viewedDocument } from '@documenso/lib/server-only/document/viewed-document';
+import { getCompletedFieldsForToken } from '@documenso/lib/server-only/field/get-completed-fields-for-token';
+import { getFieldsForToken } from '@documenso/lib/server-only/field/get-fields-for-token';
+import { getRecipientByToken } from '@documenso/lib/server-only/recipient/get-recipient-by-token';
+
+import { procedure } from '../trpc';
+import {
+  ZGetMultiSignDocumentRequestSchema,
+  ZGetMultiSignDocumentResponseSchema,
+} from './get-multi-sign-document.types';
+
+export const getMultiSignDocumentRoute = procedure
+  .input(ZGetMultiSignDocumentRequestSchema)
+  .output(ZGetMultiSignDocumentResponseSchema)
+  .query(async ({ input, ctx: { metadata } }) => {
+    try {
+      const { token } = input;
+
+      const [document, fields, recipient] = await Promise.all([
+        getDocumentAndSenderByToken({
+          token,
+          requireAccessAuth: false,
+        }).catch(() => null),
+        getFieldsForToken({ token }),
+        getRecipientByToken({ token }).catch(() => null),
+        getCompletedFieldsForToken({ token }).catch(() => []),
+      ]);
+
+      if (!document || !recipient) {
+        throw new AppError(AppErrorCode.NOT_FOUND, {
+          message: 'Document or recipient not found',
+        });
+      }
+
+      await viewedDocument({
+        token,
+        requestMetadata: metadata.requestMetadata,
+      });
+
+      // Transform fields to match our schema
+      const transformedFields = fields.map((field) => ({
+        ...field,
+        recipient,
+      }));
+
+      return {
+        ...document,
+        folder: null,
+        fields: transformedFields,
+      };
+    } catch (error) {
+      if (error instanceof AppError) {
+        throw error;
+      }
+
+      throw new AppError(AppErrorCode.UNKNOWN_ERROR, {
+        message: 'Failed to get document details',
+      });
+    }
+  });