import 'dart:io';

class BotConfig {
  BotConfig({
    required this.backendUrl,
    required this.shareDailyLimit,
    required this.apiKey,
    required this.botToken,
  });

  final String backendUrl;
  final int shareDailyLimit;
  final String apiKey;
  final String botToken;

  static const String defaultBackendUrl = 'https://api.mnemo-cards.online';
  static const int defaultShareDailyLimit = 1;

  factory BotConfig.fromEnvironment({
    Map<String, String>? environment,
  }) {
    final env = environment ?? Platform.environment;

    // Backend URL: MNEMO_BACKEND_URL or BACKEND_URL or default
    final backendUrl = <String?>[
      env['MNEMO_BACKEND_URL'],
      env['BACKEND_URL'],
      defaultBackendUrl,
    ].firstWhere(
      (value) => value != null && value.trim().isNotEmpty,
    )!;

    // Share daily limit: BOT_SHARE_DAILY_LIMIT or default
    final shareDailyLimitStr = env['BOT_SHARE_DAILY_LIMIT'];
    final shareDailyLimit = shareDailyLimitStr != null
        ? int.tryParse(shareDailyLimitStr) ?? defaultShareDailyLimit
        : defaultShareDailyLimit;

    // API Key: required
    final apiKey = env['TELEGRAM_BOT_API_KEY'];
    if (apiKey == null || apiKey.isEmpty) {
      throw Exception(
          'TELEGRAM_BOT_API_KEY environment variable is required');
    }

    // Bot Token: required
    final botToken = env['TELEGRAM_BOT_TOKEN'];
    if (botToken == null || botToken.isEmpty) {
      throw Exception('TELEGRAM_BOT_TOKEN environment variable is required');
    }

    return BotConfig(
      backendUrl: backendUrl.trim(),
      shareDailyLimit: shareDailyLimit,
      apiKey: apiKey,
      botToken: botToken,
    );
  }
}