refactor: Switch to file_picker package and get rid of some dependency overrides

lib/utils/matrix_sdk_extensions/matrix_file_extension.dart

@@ -1,9 +1,14 @@
+import 'dart:io';
+
 import 'package:flutter/material.dart';
 
-import 'package:file_picker_cross/file_picker_cross.dart';
-import 'package:image_picker/image_picker.dart';
+import 'package:file_picker/file_picker.dart';
+import 'package:flutter_gen/gen_l10n/l10n.dart';
+import 'package:future_loading_dialog/future_loading_dialog.dart';
 import 'package:matrix/matrix.dart';
+import 'package:path_provider/path_provider.dart';
 import 'package:share_plus/share_plus.dart';
+import 'package:universal_html/html.dart' as html;
 
 import 'package:fluffychat/utils/platform_infos.dart';
 import 'package:fluffychat/utils/size_string.dart';
@@ -13,10 +18,65 @@ extension MatrixFileExtension on MatrixFile {
     if (PlatformInfos.isIOS) {
       return share(context);
     }
-    final fileName = name.split('/').last;
 
-    final file = FilePickerCross(bytes);
-    await file.exportToStorage(fileName: fileName, share: false);
+    if (PlatformInfos.isWeb) {
+      _webDownload();
+      return;
+    }
+
+    final downloadPath = PlatformInfos.isAndroid
+        ? await getDownloadPathAndroid()
+        : await FilePicker.platform.saveFile(
+            dialogTitle: L10n.of(context)!.saveFile,
+            fileName: name,
+            type: filePickerFileType,
+          );
+    if (downloadPath == null) return;
+
+    final result = await showFutureLoadingDialog(
+      context: context,
+      future: () => File(downloadPath).writeAsBytes(bytes),
+    );
+    if (result.error != null) return;
+
+    ScaffoldMessenger.of(context).showSnackBar(
+      SnackBar(
+        content: Text(
+          L10n.of(context)!.fileHasBeenSavedAt(downloadPath),
+        ),
+      ),
+    );
+  }
+
+  Future<String> getDownloadPathAndroid() async {
+    final downloadDirectories = await getExternalStorageDirectories(
+      type: StorageDirectory.downloads,
+    );
+    if (downloadDirectories != null && downloadDirectories.isNotEmpty) {
+      return downloadDirectories.first.path;
+    }
+    final fallbackDirectory = await getApplicationDocumentsDirectory();
+    return fallbackDirectory.path;
+  }
+
+  FileType get filePickerFileType {
+    if (this is MatrixImageFile) return FileType.image;
+    if (this is MatrixAudioFile) return FileType.audio;
+    if (this is MatrixVideoFile) return FileType.video;
+    return FileType.any;
+  }
+
+  void _webDownload() {
+    html.AnchorElement(
+      href: html.Url.createObjectUrlFromBlob(
+        html.Blob(
+          [bytes],
+          'application/octet-stream',
+        ),
+      ),
+    )
+      ..download = name
+      ..click();
   }
 
   void share(BuildContext context) async {