import 'dart:convert';
import 'package:http/http.dart' as http;

class TelegramClient {
  final String token;
  final http.Client _http;
  final String _base;

  TelegramClient(this.token)
      : _http = http.Client(),
        _base = 'https://api.telegram.org/bot$token';

  // Долгий polling — ждёт до timeout секунд, возвращает новые апдейты
  Future<List<Map<String, dynamic>>> getUpdates({
    required int offset,
    int timeout = 30,
  }) async {
    try {
      final response = await _http.get(
        Uri.parse('$_base/getUpdates?offset=$offset&timeout=$timeout&allowed_updates=["message"]'),
        headers: {'content-type': 'application/json'},
      ).timeout(Duration(seconds: timeout + 5));

      final data = jsonDecode(response.body) as Map<String, dynamic>;
      if (data['ok'] != true) return [];
      return (data['result'] as List<dynamic>).cast<Map<String, dynamic>>();
    } catch (_) {
      return [];
    }
  }

  Future<void> sendMessage(int chatId, String text, {int? replyToMessageId}) async {
    final chunks = _splitMessage(text);
    for (final chunk in chunks) {
      final payload = <String, dynamic>{
        'chat_id': chatId,
        'text': chunk,
        'parse_mode': 'Markdown',
      };
      if (replyToMessageId != null) payload['reply_to_message_id'] = replyToMessageId;
      try {
        await _http.post(
          Uri.parse('$_base/sendMessage'),
          headers: {'content-type': 'application/json'},
          body: jsonEncode(payload),
        );
      } catch (_) {
        try {
          final plain = <String, dynamic>{'chat_id': chatId, 'text': chunk};
          if (replyToMessageId != null) plain['reply_to_message_id'] = replyToMessageId;
          await _http.post(
            Uri.parse('$_base/sendMessage'),
            headers: {'content-type': 'application/json'},
            body: jsonEncode(plain),
          );
        } catch (_) {}
      }
    }
  }

  Future<void> sendTyping(int chatId) async {
    try {
      await _http.post(
        Uri.parse('$_base/sendChatAction'),
        headers: {'content-type': 'application/json'},
        body: jsonEncode({'chat_id': chatId, 'action': 'typing'}),
      );
    } catch (_) {}
  }

  List<String> _splitMessage(String text) {
    const maxLen = 4000;
    if (text.length <= maxLen) return [text];
    final chunks = <String>[];
    var start = 0;
    while (start < text.length) {
      final end = (start + maxLen).clamp(0, text.length);
      chunks.add(text.substring(start, end));
      start = end;
    }
    return chunks;
  }

  void dispose() => _http.close();
}