import 'dart:convert';
import 'package:http/http.dart' as http;
import '../http_client.dart';
import '../http_util.dart';
import '../models.dart';
import '../sse.dart';
import 'base_provider.dart';

/// Port of g4f.Provider.OperaAria — anonymous OAuth, collect SSE to one reply.
class OperaAria extends BaseProvider {
  @override
  String get name => 'OperaAria';

  @override
  bool get working => true;

  @override
  List<String> get models => ['aria'];

  @override
  String get defaultModel => 'aria';

  static const _tokenUrl = 'https://oauth2.opera-api.com/oauth2/v1/token/';
  static const _signupUrl =
      'https://auth.opera.com/account/v2/external/anonymous/signup';
  static const _chatUrl = 'https://composer.opera-api.com/api/v2/a-chat';
  static const _secret =
      'Pcc5NvlCrxl02pMw32kO6WrnhpS0pUZ95YrDP8XNKJJQvFht4wQDkFJ7v9x5hn7C';

  @override
  Stream<String> createAsyncGenerator(
    String model,
    List<Message> messages, {
    bool stream = false,
  }) async* {
      final tokenHeaders = {
        'User-Agent': 'okhttp/5.3.2',
        'Content-Type': 'application/x-www-form-urlencoded',
        'x-requested-with': 'XMLHttpRequest',
        'x-opera-client-cache': '1',
      };
      final anon = await g4fHttp.post(
        Uri.parse(_tokenUrl),
        headers: tokenHeaders,
        body: {
          'client_id': 'mini-client',
          'client_secret': _secret,
          'grant_type': 'client_credentials',
          'scope': 'anonymous_account',
        },
      ).timeout(const Duration(seconds: 12));
      if (anon.statusCode != 200) {
        throw Exception('Opera anon ${anon.statusCode}');
      }
      final anonToken = jsonDecode(anon.body)['access_token'] as String;

      final signup = await g4fHttp.post(
        Uri.parse(_signupUrl),
        headers: {
          'User-Agent': 'okhttp/5.3.2',
          'Authorization': 'Bearer $anonToken',
          'Accept': 'application/json',
          'Content-Type': 'application/json; charset=utf-8',
          'x-requested-with': 'XMLHttpRequest',
          'x-opera-client-cache': '1',
        },
        body: jsonEncode({'client_id': 'mini'}),
      ).timeout(const Duration(seconds: 12));
      if (signup.statusCode != 200) {
        throw Exception('Opera signup ${signup.statusCode}');
      }
      final authToken = jsonDecode(signup.body)['token'] as String;

      final refresh = await g4fHttp.post(
        Uri.parse(_tokenUrl),
        headers: tokenHeaders,
        body: {
          'auth_token': authToken,
          'client_id': 'mini',
          'grant_type': 'auth_token',
          'scope': 'shodan:aria',
        },
      ).timeout(const Duration(seconds: 12));
      if (refresh.statusCode != 200) {
        throw Exception('Opera refresh ${refresh.statusCode}');
      }
      final access = jsonDecode(refresh.body)['access_token'] as String;

      final req = http.Request('POST', Uri.parse(_chatUrl));
      req.headers.addAll({
        'Accept': 'text/event-stream',
        'Authorization': 'Bearer $access',
        'Content-Type': 'application/json',
        'Origin': 'https://composer.opera-api.com',
        'Referer': 'https://composer.opera-api.com/assets/aria/index.html',
        'User-Agent':
            'Mozilla/5.0 (Linux; U; Android 14; Pixel 8 Pro Build/UQ1A.240205.004; wv) AppleWebKit/537.36 (KHTML, like Gecko) Version/4.0 Chrome/138.0.7204.179 Mobile Safari/537.36 OPR/99.0.2254.81922',
        'X-Opera-Timezone': '+03:00',
        'X-Opera-UI-Language': 'en',
        'X-Requested-With': 'com.opera.mini.native',
      });
      req.body = jsonEncode({
        'query': formatPrompt(messages),
        'sia': true,
        'think_harder': false,
        'supported_features': [],
        'file_attachments': [],
      });
      final res = await g4fHttp.send(req).timeout(requestTimeout);
      if (res.statusCode != 200) {
        throw Exception('Opera chat ${res.statusCode}');
      }
      final raw = utf8.decode(await res.stream.toBytes().timeout(requestTimeout));
      final buf = StringBuffer();
      for (final piece in extractAllSseContent(raw)) {
        buf.write(piece);
      }
      if (buf.isEmpty) {
        // v2 envelope: {"response":{"message":"..."}}
        for (final line in raw.split('\n')) {
          if (!line.contains('{')) continue;
          try {
            final data = jsonDecode(line.startsWith('data:') ? line.substring(5) : line);
            if (data is Map) {
              final msg = data['response'] is Map
                  ? (data['response'] as Map)['message']
                  : data['message'];
              if (msg is String) buf.write(msg);
            }
          } catch (_) {}
        }
      }
      final text = buf.toString().trim();
      if (!looksLikeModelOutput(text)) throw Exception('Opera empty');
      yield text;
  }
}