Fixed issue where http client settings were not synchronised with appdata. Close #337

lib/network/proxy.dart

@@ -0,0 +1,60 @@
+import 'package:flutter/services.dart';
+import 'package:venera/foundation/app.dart';
+import 'package:venera/foundation/appdata.dart';
+import 'package:venera/utils/ext.dart';
+
+String? _cachedProxy;
+
+DateTime? _cachedProxyTime;
+
+Future<String?> getProxy() async {
+  if (_cachedProxyTime != null &&
+      DateTime.now().difference(_cachedProxyTime!).inSeconds < 1) {
+    return _cachedProxy;
+  }
+  String? proxy = await _getProxy();
+  _cachedProxy = proxy;
+  _cachedProxyTime = DateTime.now();
+  return proxy;
+}
+
+Future<String?> _getProxy() async {
+  if ((appdata.settings['proxy'] as String).removeAllBlank == "direct") {
+    return null;
+  }
+  if (appdata.settings['proxy'] != "system") return appdata.settings['proxy'];
+
+  String res;
+  if (!App.isLinux) {
+    const channel = MethodChannel("venera/method_channel");
+    try {
+      res = await channel.invokeMethod("getProxy");
+    } catch (e) {
+      return null;
+    }
+  } else {
+    res = "No Proxy";
+  }
+  if (res == "No Proxy") return null;
+
+  if (res.contains(";")) {
+    var proxies = res.split(";");
+    for (String proxy in proxies) {
+      proxy = proxy.removeAllBlank;
+      if (proxy.startsWith('https=')) {
+        return proxy.substring(6);
+      }
+    }
+  }
+
+  final RegExp regex = RegExp(
+    r'^\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}:\d+$',
+    caseSensitive: false,
+    multiLine: false,
+  );
+  if (!regex.hasMatch(res)) {
+    return null;
+  }
+
+  return res;
+}