refactor: Use custom decorator for upload files

apps/api/.eslintrc.json

@@ -10,7 +10,20 @@
     },
     {
       "files": ["*.ts", "*.tsx"],
-      "rules": {}
+      "rules": {
+        "no-restricted-imports": [
+          "error",
+          {
+            "paths": [
+              {
+                "name": "@nestjs/common",
+                "importNames": ["UploadedFile", "UploadedFiles"],
+                "message": "Import UploadedFile/UploadedFiles from the local 'common/uploaded-file.decorator' module (use the appropriate relative path, e.g. '../common/uploaded-file.decorator') instead. The custom decorators re-encode `file.originalname` from latin1 to UTF-8 so non-ASCII filenames are stored correctly."
+              }
+            ]
+          }
+        ]
+      }
     },
     {
       "files": ["*.js", "*.jsx"],

apps/api/src/bank-transactions-file/bank-transactions-file.controller.ts

@@ -15,7 +15,8 @@ import {
 import { BankTransactionsFileService } from './bank-transactions-file.service'
 import 'multer'
 import { FilesInterceptor } from '@nestjs/platform-express'
-import { UseInterceptors, UploadedFiles } from '@nestjs/common'
+import { UseInterceptors } from '@nestjs/common'
+import { UploadedFiles } from '../common/uploaded-file.decorator'
 import { AuthenticatedUser, Public, RoleMatchingMode, Roles } from 'nest-keycloak-connect'
 import { RealmViewSupporters, ViewSupporters } from '@podkrepi-bg/podkrepi-types'
 import { FilesTypesDto } from './dto/files-type.dto'

apps/api/src/campaign-application/campaign-application.controller.ts

@@ -11,9 +11,9 @@ import {
   Post,
   Response,
   StreamableFile,
-  UploadedFiles,
   UseInterceptors,
 } from '@nestjs/common'
+import { UploadedFiles } from '../common/uploaded-file.decorator'
 import { FilesInterceptor } from '@nestjs/platform-express'
 import { ApiTags } from '@nestjs/swagger'
 import { AuthenticatedUser } from 'nest-keycloak-connect'

apps/api/src/campaign-application/campaign-application.service.ts

@@ -321,9 +321,8 @@ export class CampaignApplicationService {
     campaignApplicationId: string,
   ) {
 
-    const decodedFilename = Buffer.from(file.originalname, 'base64').toString('utf-8')
     const fileDto: CreateCampaignApplicationFileDto = {
-      filename: decodedFilename,
+      filename: file.originalname,
       mimetype: file.mimetype,
       campaignApplicationId: campaignApplicationId,
       personId,

apps/api/src/campaign-file/campaign-file.controller.ts

@@ -14,7 +14,8 @@ import {
   forwardRef,
 } from '@nestjs/common'
 import { FilesInterceptor } from '@nestjs/platform-express'
-import { UseInterceptors, UploadedFiles } from '@nestjs/common'
+import { UseInterceptors } from '@nestjs/common'
+import { UploadedFiles } from '../common/uploaded-file.decorator'
 import { RoleMatchingMode, Roles } from 'nest-keycloak-connect'
 import { RealmViewSupporters, ViewSupporters } from '@podkrepi-bg/podkrepi-types'
 import { Public, AuthenticatedUser } from 'nest-keycloak-connect'

apps/api/src/campaign-news-file/campaign-news-file.controller.ts

@@ -13,12 +13,13 @@
   ForbiddenException,
 } from '@nestjs/common'
 import { FilesInterceptor } from '@nestjs/platform-express'
-import { UseInterceptors, UploadedFiles } from '@nestjs/common'
+import { UseInterceptors } from '@nestjs/common'
+import { UploadedFiles } from '../common/uploaded-file.decorator'
 import { Public, AuthenticatedUser } from 'nest-keycloak-connect'
 import { PersonService } from '../person/person.service'
 import { FilesRoleDto } from './dto/files-role.dto'
 import { CampaignNewsFileService } from './campaign-news-file.service'
 import { KeycloakTokenParsed, isAdmin } from '../auth/keycloak'
 import { ApiTags } from '@nestjs/swagger'
 import { validateFileType } from '../common/files'
 import { CampaignNewsService } from '../campaign-news/campaign-news.service'

apps/api/src/common/uploaded-file.decorator.ts

@@ -0,0 +1,45 @@
+import { createParamDecorator, ExecutionContext } from '@nestjs/common'
+
+/**
+ * Multer (Busboy) decodes multipart filename headers as latin1 by default,
+ * so non-ASCII filenames arrive on `file.originalname` as mojibake. These
+ * decorators replace Nest's built-in `UploadedFile` / `UploadedFiles` and
+ * re-decode `originalname` as UTF-8 before the controller sees the file.
+ *
+ * Use these in place of the Nest decorators on every multipart upload
+ * handler so non-ASCII filenames are stored correctly everywhere.
+ */
+
+type AnyFile = { originalname?: string } & Record<string, unknown>
+
+/**
+ * Returns a shallow copy of `file` with `originalname` re-decoded from
+ * latin1 to UTF-8. We deliberately do NOT mutate the original Multer file
+ * object, so the request stays pristine for any other consumer (guards,
+ * interceptors, exception filters) and so this conversion stays idempotent
+ * — running it twice on the same input always yields the same result.
+ */
+const withDecodedFilename = <T extends AnyFile>(file: T): T => {
+  if (!file || typeof file.originalname !== 'string') return file
+  return {
+    ...file,
+    originalname: Buffer.from(file.originalname, 'latin1').toString('utf8'),
+  }
+}
+
+export const UploadedFile = createParamDecorator((_data: unknown, ctx: ExecutionContext) => {
+  const file = ctx.switchToHttp().getRequest().file
+  return file ? withDecodedFilename(file) : file
+})
+
+export const UploadedFiles = createParamDecorator((_data: unknown, ctx: ExecutionContext) => {
+  const files = ctx.switchToHttp().getRequest().files
+  if (!files) return files
+  if (Array.isArray(files)) return files.map(withDecodedFilename)
+  // FileFieldsInterceptor: { [field]: Express.Multer.File[] }
+  const result: Record<string, AnyFile[]> = {}
+  for (const key of Object.keys(files)) {
+    result[key] = files[key].map(withDecodedFilename)
+  }
+  return result
+})

apps/api/src/expenses/expenses.controller.ts

@@ -20,7 +20,8 @@ import { ExpensesService } from './expenses.service'
 import { CreateExpenseDto } from './dto/create-expense.dto'
 import { UpdateExpenseDto } from './dto/update-expense.dto'
 import { ApiTags } from '@nestjs/swagger'
-import { UseInterceptors, UploadedFiles } from '@nestjs/common'
+import { UseInterceptors } from '@nestjs/common'
+import { UploadedFiles } from '../common/uploaded-file.decorator'
 import { FilesInterceptor } from '@nestjs/platform-express'
 import { validateFileType } from '../common/files'
 

apps/api/src/irregularity-file/irregularity-file.controller.ts

@@ -13,7 +13,8 @@ import {
 } from '@nestjs/common'
 
 import { FilesInterceptor } from '@nestjs/platform-express'
-import { UseInterceptors, UploadedFiles } from '@nestjs/common'
+import { UseInterceptors } from '@nestjs/common'
+import { UploadedFiles } from '../common/uploaded-file.decorator'
 import { Roles, RoleMatchingMode, Public } from 'nest-keycloak-connect'
 
 import { PersonService } from '../person/person.service'