refactor(contractor-onboarding): transform correctly base64 files (#712)

* feat(contractor-onboarding) - fix update files

* fix tests

Author: gabrielseco

src/flows/ContractorOnboarding/hooks.tsx

@@ -56,6 +56,7 @@ import {
   buildContractPreviewJsfModify,
 } from '@/src/flows/ContractorOnboarding/jsfModify';
 import { useUploadFile } from '@/src/common/api/files';
+import { dataURLtoFile } from '@/src/lib/files';
 
 type useContractorOnboardingProps = Omit<
   ContractorOnboardingFlowProps,
@@ -421,9 +422,7 @@ export const useContractorOnboarding = ({
       saudi_nationality_status: employment?.contract_details?.nationality,
       ...(ir35File?.content && {
         ir35_sds_file: [
-          new File([ir35File.content as unknown as string], ir35File.name, {
-            type: 'application/pdf',
-          }),
+          dataURLtoFile(ir35File.content as unknown as string, ir35File.name),
         ],
       }),
     };

src/flows/ContractorOnboarding/tests/ContractorOnboarding.test.tsx

@@ -380,7 +380,8 @@ describe('ContractorOnboardingFlow', () => {
               id: '643e3627-320e-44a9-9721-7b9a3cf5b946',
               name: 'test-sds.pdf',
               type: 'other',
-              content: 'data:application/pdf;base64,JVBERi0xLjQKJeLjz9MK...', // Truncated base64
+              content:
+                'data:application/pdf;base64,JVBERi0xLjQKMSAwIG9iago8PAovVGl0bGUgKP7/KQovQ3JlYXRvciAo/v8AdwBrAGgAdABtAGwAdABvAHAAZABmACAAMAAuADEAMgAuADYALgAxKQovUHJvZHVjZXIgKP7/AFEAdAAgADQALgA4AC4ANykKL0NyZWF0aW9uRGF0ZSAoRDoyMDI1MTAyMzE1MjEwNFopCj4+CmVuZG9iagozIDAgb2JqCjw8Ci9UeXBlIC9FeHRHU3RhdGUKL1NBIHRydWUKL1NNIDAuMDIKL2NhIDEuMAovQ0EgMS4wCi9BSVMgZmFsc2UKL1NNYXNrIC9Ob25lPj4KZW5kb2JqCjQgMCBvYmoKWy9QYXR0ZXJuIC9E',
               inserted_at: '2026-01-26T11:08:56Z',
               sub_type: 'ir_35',
             },

src/lib/files.ts

@@ -22,3 +22,19 @@ export const convertFilesToBase64 = async (files: File[]) => {
   );
   return base64Files;
 };
+
+/**
+ * Convert a data URL to a File object
+ * @param dataURL - The data URL to convert
+ * @param filename - The name of the file
+ * @returns The File object
+ */
+export function dataURLtoFile(dataURL: string, filename: string): File {
+  const arr = dataURL.split(',');
+  const mime = arr[0].match(/:(.*?);/)?.[1];
+  const bstr = atob(arr[1]);
+
+  const u8arr = Uint8Array.from(bstr, (char) => char.charCodeAt(0));
+
+  return new File([u8arr], filename, { type: mime });
+}