refactor: settings page

ui/lib/widgets/utils.dart

@@ -0,0 +1,64 @@
+import 'dart:math';
+
+import 'package:flutter/material.dart';
+import 'package:intl/intl.dart';
+import 'package:ui/providers/APIs.dart';
+
+class Utils {
+  static Future<void> showAlertDialog(BuildContext context, String msg) async {
+    return showDialog<void>(
+      context: context,
+      barrierDismissible: true, // user must tap button!
+      builder: (BuildContext context) {
+        return AlertDialog(
+          title: const Text('警告 ⚠️'),
+          content: SingleChildScrollView(
+            child: ListBody(
+              children: <Widget>[
+                Text(msg),
+              ],
+            ),
+          ),
+          actions: <Widget>[
+            TextButton(
+              child: const Text('确定'),
+              onPressed: () {
+                Navigator.of(context).pop();
+              },
+            ),
+          ],
+        );
+      },
+    );
+  }
+
+  static showSnakeBar(String msg) {
+    final context = APIs.navigatorKey.currentContext;
+    if (context != null) {
+      ScaffoldMessenger.of(context).showSnackBar(SnackBar(
+        content: Text(msg),
+        showCloseIcon: true,
+      ));
+    }
+  }
+
+  static bool showError(BuildContext context, AsyncSnapshot snapshot) {
+    final isErrored = snapshot.hasError &&
+        snapshot.connectionState != ConnectionState.waiting;
+    if (isErrored) {
+      Utils.showSnakeBar("当前操作出错: ${snapshot.error}");
+      return true;
+    }
+    return false;
+  }
+}
+
+extension FileFormatter on num {
+  String readableFileSize({bool base1024 = true}) {
+    final base = base1024 ? 1024 : 1000;
+    if (this <= 0) return "0";
+    final units = ["B", "kB", "MB", "GB", "TB"];
+    int digitGroups = (log(this) / log(base)).round();
+    return "${NumberFormat("#,##0.#").format(this / pow(base, digitGroups))} ${units[digitGroups]}";
+  }
+}