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lib/pods/network.dart

@@ -1,8 +1,50 @@
+import 'dart:async';
+import 'dart:convert';
+import 'dart:developer';
+import 'dart:io';
+
+import 'package:flutter/foundation.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
 import 'package:dio/dio.dart';
+import 'package:package_info_plus/package_info_plus.dart';
+import 'package:device_info_plus/device_info_plus.dart';
+import 'package:island/models/auth.dart';
+import 'package:shared_preferences/shared_preferences.dart';
+
 import 'config.dart';
 
-final dioProvider = Provider<Dio>((ref) {
+final userAgentProvider = FutureProvider<String>((ref) async {
+  final String platformInfo;
+  if (kIsWeb) {
+    final deviceInfo = await DeviceInfoPlugin().webBrowserInfo;
+    platformInfo = 'Web; ${deviceInfo.vendor}';
+  } else if (Platform.isAndroid) {
+    final deviceInfo = await DeviceInfoPlugin().androidInfo;
+    platformInfo =
+        'Android; ${deviceInfo.brand} ${deviceInfo.model}; ${deviceInfo.id}';
+  } else if (Platform.isIOS) {
+    final deviceInfo = await DeviceInfoPlugin().iosInfo;
+    platformInfo = 'iOS; ${deviceInfo.model}; ${deviceInfo.name}';
+  } else if (Platform.isMacOS) {
+    final deviceInfo = await DeviceInfoPlugin().macOsInfo;
+    platformInfo = 'MacOS; ${deviceInfo.model}; ${deviceInfo.hostName}';
+  } else if (Platform.isWindows) {
+    final deviceInfo = await DeviceInfoPlugin().windowsInfo;
+    platformInfo =
+        'Windows NT; ${deviceInfo.productName}; ${deviceInfo.computerName}';
+  } else if (Platform.isLinux) {
+    final deviceInfo = await DeviceInfoPlugin().linuxInfo;
+    platformInfo = 'Linux; ${deviceInfo.prettyName}';
+  } else {
+    platformInfo = 'Unknown';
+  }
+
+  final packageInfo = await PackageInfo.fromPlatform();
+
+  return 'Solian/${packageInfo.version}+${packageInfo.buildNumber} ($platformInfo)';
+});
+
+final apiClientProvider = Provider<Dio>((ref) {
   final serverUrl = ref.watch(serverUrlProvider);
   final dio = Dio(
     BaseOptions(
@@ -16,5 +58,127 @@ final dioProvider = Provider<Dio>((ref) {
     ),
   );
 
+  dio.interceptors.add(
+    InterceptorsWrapper(
+      onRequest: (
+        RequestOptions options,
+        RequestInterceptorHandler handler,
+      ) async {
+        final atk = await getFreshAtk(ref);
+        if (atk != null) {
+          options.headers['Authorization'] = 'Bearer $atk';
+        }
+        final userAgent = ref.watch(userAgentProvider);
+        if (userAgent.value != null) {
+          options.headers['User-Agent'] = userAgent.value;
+        }
+        return handler.next(options);
+      },
+    ),
+  );
+
   return dio;
 });
+
+final tokenPairProvider = Provider<AppTokenPair?>((ref) {
+  final prefs = ref.watch(sharedPreferencesProvider);
+  final tkPairString = prefs.getString(kTokenPairStoreKey);
+  if (tkPairString == null) return null;
+  return AppTokenPair.fromJson(jsonDecode(tkPairString));
+});
+
+Future<(String, String)?> refreshToken(Ref ref, String? rtk) async {
+  if (rtk == null) return null;
+
+  final baseUrl = ref.watch(serverUrlProvider);
+
+  final dio = Dio();
+  dio.options.baseUrl = baseUrl;
+
+  final resp = await dio.post(
+    '/auth/token',
+    data: {'grant_type': 'refresh_token', 'refresh_token': rtk},
+  );
+
+  final String atk = resp.data['access_token'];
+  final String nRtk = resp.data['refresh_token'];
+  setTokenPair(ref.watch(sharedPreferencesProvider), atk, nRtk);
+  ref.invalidate(tokenPairProvider);
+
+  return (atk, nRtk);
+}
+
+Completer<String?>? _refreshCompleter;
+
+Future<String?> getFreshAtk(Ref ref) async {
+  final tkPair = ref.watch(tokenPairProvider);
+  var atk = tkPair?.accessToken;
+  var rtk = tkPair?.refreshToken;
+
+  if (_refreshCompleter != null) {
+    return await _refreshCompleter!.future;
+  } else {
+    _refreshCompleter = Completer<String?>();
+  }
+
+  try {
+    if (atk != null) {
+      final atkParts = atk.split('.');
+      if (atkParts.length != 3) {
+        throw Exception('invalid format of access token');
+      }
+
+      var rawPayload = atkParts[1].replaceAll('-', '+').replaceAll('_', '/');
+      switch (rawPayload.length % 4) {
+        case 0:
+          break;
+        case 2:
+          rawPayload += '==';
+          break;
+        case 3:
+          rawPayload += '=';
+          break;
+        default:
+          throw Exception('illegal format of access token payload');
+      }
+
+      final b64 = utf8.fuse(base64Url);
+      final payload = b64.decode(rawPayload);
+      final exp = jsonDecode(payload)['exp'];
+      if (exp <= DateTime.now().millisecondsSinceEpoch ~/ 1000) {
+        log('[Auth] Access token need refresh, doing it at ${DateTime.now()}');
+        final result = await refreshToken(ref, rtk);
+        if (result == null) {
+          atk = null;
+        } else {
+          atk = result.$1;
+        }
+      }
+
+      if (atk != null) {
+        _refreshCompleter!.complete(atk);
+        return atk;
+      } else {
+        log('[Auth] Access token refresh failed...');
+        _refreshCompleter!.complete(null);
+      }
+    }
+  } catch (err) {
+    log('[Auth] Failed to authenticate user... $err');
+    _refreshCompleter!.completeError(err);
+  } finally {
+    _refreshCompleter = null;
+  }
+
+  return null;
+}
+
+Future<void> setTokenPair(
+  SharedPreferences prefs,
+  String atk,
+  String rtk,
+) async {
+  final tkPair = AppTokenPair(accessToken: atk, refreshToken: rtk);
+  final tkPairString = jsonEncode(tkPair);
+  prefs.setString(kTokenPairStoreKey, tkPairString);
+}