core: Determine User-Agent using package_info_plus package

Author: sirpengi

lib/api/core.dart

@@ -1,7 +1,9 @@
 import 'dart:convert';
 import 'dart:io';
 
+import 'package:device_info_plus/device_info_plus.dart';
 import 'package:http/http.dart' as http;
+import 'package:package_info_plus/package_info_plus.dart';
 
 import '../log.dart';
 import '../model/localizations.dart';
@@ -69,8 +71,24 @@ class ApiConnection {
     }
   }
 
-  void addUserAgent(http.BaseRequest request) {
-    request.headers['User-Agent'] = 'ZulipMobile/?.?.? (Android 14)';
+  Future<void> addUserAgent(http.BaseRequest request) async {
+    final packageInfo = await PackageInfo.fromPlatform();
+    final String applicationVersion = packageInfo.version;
+    final String systemName;
+    final String systemVersion;
+    final deviceInfo = await DeviceInfoPlugin().deviceInfo;
+    switch (deviceInfo) {
+      case IosDeviceInfo():
+        systemName = deviceInfo.systemName;
+        systemVersion = deviceInfo.systemVersion;
+      case AndroidDeviceInfo():
+        systemName = "Android";
+        systemVersion = deviceInfo.version.release;
+      default:
+        systemName = "Desktop";
+        systemVersion = "?";
+    }
+    request.headers['User-Agent'] = 'ZulipMobile/$applicationVersion ($systemName $systemVersion)';
   }
 
   final http.Client _client;
@@ -84,7 +102,7 @@ class ApiConnection {
     assert(debugLog("${request.method} ${request.url}"));
 
     addAuth(request);
-    addUserAgent(request);
+    await addUserAgent(request);
 
     final http.StreamedResponse response;
     try {