fix: start duplicate server on mobile when the app is closed by swiping (#370)

ui/flutter/lib/database/database.dart

@@ -6,6 +6,7 @@ import 'package:hive/hive.dart';
 import 'entity.dart';
 
 const String _startConfig = 'startConfig';
+const String _lastRunningConfig = 'lastRunningConfig';
 const String _windowState = 'windowState';
 const String _bookmark = 'bookmark';
 const String _createHistory = 'createHistory';
@@ -53,6 +54,15 @@ class Database {
         _startConfig, (json) => StartConfigEntity.fromJson(json));
   }
 
+  void saveLastRunningConfig(StartConfigEntity entity) {
+    save<StartConfigEntity>(_lastRunningConfig, entity);
+  }
+
+  StartConfigEntity? getLastRunningConfig() {
+    return get<StartConfigEntity>(
+        _lastRunningConfig, (json) => StartConfigEntity.fromJson(json));
+  }
+
   /// Patch non-null fields with the original value
   void saveWindowState(WindowStateEntity entity) {
     final state = getWindowState();

ui/flutter/lib/main.dart

@@ -1,5 +1,6 @@
 import 'package:flutter/foundation.dart';
 import 'package:flutter/material.dart';
+import 'package:flutter_foreground_task/flutter_foreground_task.dart';
 import 'package:get/get.dart';
 import 'package:window_manager/window_manager.dart';
 
@@ -8,6 +9,7 @@ import 'app/modules/app/controllers/app_controller.dart';
 import 'app/modules/app/views/app_view.dart';
 import 'core/libgopeed_boot.dart';
 import 'database/database.dart';
+import 'database/entity.dart';
 import 'i18n/message.dart';
 import 'util/locale_manager.dart';
 import 'util/log_util.dart';
@@ -52,8 +54,23 @@ Future<void> init() async {
   try {
     await controller.loadStartConfig();
     final startCfg = controller.startConfig.value;
-    controller.runningPort.value = await LibgopeedBoot.instance.start(startCfg);
-    api.init(startCfg.network, controller.runningAddress(), startCfg.apiToken);
+    // When the app is closed by swiping on the mobile, the backend server is actually still running, don't need to start again.
+    final isRunning =
+        Util.isMobile() && (await FlutterForegroundTask.isRunningService);
+    if (!isRunning) {
+      controller.runningPort.value =
+          await LibgopeedBoot.instance.start(startCfg);
+      api.init(
+          startCfg.network, controller.runningAddress(), startCfg.apiToken);
+      Database.instance.saveLastRunningConfig(StartConfigEntity(
+          network: startCfg.network,
+          address: controller.runningAddress(),
+          apiToken: startCfg.apiToken));
+    } else {
+      final lastRunningConfig = Database.instance.getLastRunningConfig()!;
+      api.init(lastRunningConfig.network, lastRunningConfig.address,
+          lastRunningConfig.apiToken);
+    }
   } catch (e) {
     logger.e("libgopeed init fail", e);
   }