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

class ChatGptOss extends BaseProvider {
  @override
  String get name => 'ChatGptOss';

  @override
  bool get working => true;

  @override
  List<String> get models => ['gpt-oss-120b', 'gpt-5-nano'];

  @override
  String get defaultModel => 'gpt-oss-120b';

  String _generateFingerprint() {
    final seed = '${DateTime.now().millisecondsSinceEpoch / 1000.0}-${Random().nextDouble()}';
    return md5.convert(utf8.encode(seed)).toString();
  }

  @override
  Stream<String> createAsyncGenerator(
    String model,
    List<Message> messages, {
    bool stream = false,
  }) async* {
    final prompt = formatPrompt(messages);
    final url = Uri.parse('https://chat-gpt-oss.com/api/message');

    final payload = {
      "conversation_id": null,
      "model": model,
      "content": prompt,
      "reasoning_effort": "low",
    };

    final req = http.Request('POST', url);
    req.headers.addAll({
      "accept": "text/event-stream",
      "accept-language": "en-US,en;q=0.9",
      "cache-control": "no-cache",
      "content-type": "application/json",
      "origin": "https://chat-gpt-oss.com",
      "pragma": "no-cache",
      "referer": "https://chat-gpt-oss.com/",
      "sec-ch-ua": '"Chromium";v="148", "Google Chrome";v="148", "Not/A)Brand";v="99"',
      "sec-ch-ua-mobile": "?0",
      "sec-ch-ua-platform": '"Linux"',
      "sec-fetch-dest": "empty",
      "sec-fetch-mode": "cors",
      "sec-fetch-site": "same-origin",
      "user-agent": "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/148.0.0.0 Safari/537.36",
      "x-fingerprint": _generateFingerprint(),
    });
    
    req.body = jsonEncode(payload);
    
    final response = await g4fHttp.send(req);

    if (response.statusCode == 200) {
        String? currentEvent;
        await for (final line in splitSseLines(response.stream.transform(utf8.decoder))) {
          final trimmed = line.trim();
          if (trimmed.isEmpty) {
            currentEvent = null;
            continue;
          }
          if (trimmed.startsWith('event:')) {
            currentEvent = trimmed.substring(6).trim();
            if (currentEvent == 'summary') {
              return;
            }
            continue;
          }
          if (trimmed.startsWith('data:') && currentEvent == 'message') {
            final dataStr = trimmed.substring(5).trim();
            if (dataStr.isEmpty) continue;
            try {
              final jsonChunk = jsonDecode(dataStr);
              final content = jsonChunk['content'] as String?;
              if (content != null && content.isNotEmpty) {
                yield content;
              }
            } catch (_) {}
          }
        }
    } else {
      throw Exception('$name returned status ${response.statusCode}');
    }
  }
}