fix(file-service): provide required size to pick-upload functions (#94)

* fix(file-service): provide required size to pick upload functions

* fix(file-service): throw error when file size exceeds

* fix(file-service): test commit

* fix(file-service): document things

* fix(file-service): document more things

lib/src/modules/common/file_upload/file_uploader.dart

@@ -1,44 +1,70 @@
-import 'package:fa_flutter_core/fa_flutter_core.dart';
+import 'package:image_picker/image_picker.dart';
 import 'package:file_picker/file_picker.dart';
-import 'package:open_file/src/platform/open_file.dart';
+import 'package:open_file/open_file.dart';
 
 class FileService {
   FileService._();
 
-  /// Return the Clicked Image
+  /// Picks an image and returns a `PlatformFile`.
+  /// The file size should be in MB.
+  /// No limit for file size if [requiredFileSize] is null
+  /// this will throw error if file size exceeds [requiredFileSize].
+
   static Future<PlatformFile?> pickImage(
-      ImageSource source, String? name) async {
+      ImageSource source, String? name, double? requiredFileSize) async {
     final pickedFile = await ImagePicker().pickImage(source: source);
 
     if (pickedFile != null) {
+      if (requiredFileSize != null) {
+        final fileSizeInBytes = requiredFileSize * 1024 * 1024;
+        final pickedFileSize = await pickedFile.length();
+
+        if (pickedFileSize > fileSizeInBytes) {
+          throw Exception("File size exceeds the $requiredFileSize MB limit");
+        }
+      }
+
       return PlatformFile(
         name: name ?? pickedFile.name,
         size: await pickedFile.length(),
         path: pickedFile.path,
       );
     }
+
     return null;
   }
 
-  /// Return the Picked File from the System
-  /// handled extensions are [pdf, jpeg, jpg, png]
-  /// We can add more via [extension] parameter
-  static Future<PlatformFile?> pickDocument(List<String>? extensions) async {
+  /// Picks a document from the system and returns a `PlatformFile`.
+  /// Handled extensions are [pdf, jpeg, jpg, png]. More can be added via the `extensions` parameter.
+  /// The file size should be in MB.
+  /// No limit for file size if [requiredFileSize] is null
+  /// this will throw error if file size exceeds [requiredFileSize].
+
+  static Future<PlatformFile?> pickDocument(
+      List<String>? extensions, double? requiredFileSize) async {
     FilePickerResult? result = await FilePicker.platform.pickFiles(
       type: FileType.custom,
-      allowedExtensions: extensions ??
-          [
-            'pdf',
-            'jpg',
-            'jpeg',
-            'png',
-          ],
+      allowedExtensions: extensions ?? ['pdf', 'jpg', 'jpeg', 'png'],
     );
-    if (result != null) return result.files.first;
+
+    if (result != null && result.files.isNotEmpty) {
+      final pickedFile = result.files.first;
+
+      if (requiredFileSize != null) {
+        final fileSizeInBytes = requiredFileSize * 1024 * 1024;
+
+        if (pickedFile.size > fileSizeInBytes) {
+          throw Exception("File size exceeds the $requiredFileSize MB limit");
+        }
+      }
+
+      return pickedFile;
+    }
+
     return null;
   }
 
-  /// Open the DOC
+  /// Opens the document at the specified path.
   static void openFile(String path) {
     OpenFile.open(path);
   }