import 'dart:math';

class H5Line {
  const H5Line({
    required this.label,
    required this.url,
  });

  final String label;
  final String url;

  Uri get uri => Uri.parse(url);
}

enum Environment {
  development,
  staging,
  production,
}

class AppConfig {
  static const String appName = '本地打包';
  static const String appLogo = '';

  static const String flutterShellMarkerQueryKey = 'flutter_shell';
  static const String flutterShellUrlQueryKey = 'flutter_shell_url';
  static const List<String> wildcardH5DomainTemplates = [
    '*.albzyuxq.vip',
    '*.zdyswvnt.vip',
    '*.gxifpxcr.vip',
  ];
  static const Environment currentEnvironment = Environment.production;

  // Kept for the packaging service's legacy domain rewrite step.
  static final Map<Environment, List<String>> _environmentHosts = {
    Environment.production: [
      '*.albzyuxq.vip',
      '*.zdyswvnt.vip',
      '*.gxifpxcr.vip',
    ],
  };

  static final Random _random = Random.secure();

  static H5Line get h5Line => createRandomH5Line();

  static H5Line createRandomH5Line({
    int attempt = 0,
    String Function()? wildcardFactory,
  }) {
    final templates = _h5DomainTemplatesForCurrentEnvironment;
    final template = templates[attempt.abs() % templates.length];
    return h5LineFromUrl(
      _buildFlutterShellHomeUrl(
        _replaceWildcardHost(template, wildcardFactory: wildcardFactory),
      ),
    );
  }

  static List<String> get _h5DomainTemplatesForCurrentEnvironment {
    final environmentHosts = _environmentHosts[currentEnvironment];
    if (environmentHosts == null || environmentHosts.isEmpty) {
      return wildcardH5DomainTemplates;
    }
    return environmentHosts;
  }

  static H5Line h5LineFromUrl(String value) {
    return H5Line(label: '线路1', url: _normalizeHomeUrl(value));
  }

  static String originForUrl(String value) {
    final uri = Uri.parse(value);
    return '${uri.scheme}://${uri.authority}';
  }

  static String _buildFlutterShellHomeUrl(String host) {
    final normalized = _normalizeHomeUrl(host);
    final uri = Uri.parse(normalized);
    final origin = originForUrl(normalized);
    final queryParameters = Map<String, String>.from(uri.queryParameters)
      ..[flutterShellMarkerQueryKey] = '1'
      ..[flutterShellUrlQueryKey] = origin;
    return uri.replace(queryParameters: queryParameters).toString();
  }

  static String _normalizeHomeUrl(String host) {
    final value = host.trim();
    if (value.isEmpty) {
      throw const FormatException('Empty H5 line URL');
    }

    final normalized =
        value.startsWith('http://') || value.startsWith('https://')
            ? value
            : 'https://$value';
    final uri = Uri.parse(normalized);
    final path = uri.path.isEmpty ? '/' : uri.path;
    return uri.replace(path: path).toString();
  }

  static String _replaceWildcardHost(
    String value, {
    String Function()? wildcardFactory,
  }) {
    if (!value.contains('*.')) {
      return value;
    }

    return value.replaceAllMapped(
      '*.',
      (_) => '${(wildcardFactory ?? _randomWildcardLabel)()}.',
    );
  }

  static String _randomWildcardLabel() {
    const alphabet = 'abcdefghijklmnopqrstuvwxyz0123456789';
    final label = StringBuffer();
    for (var index = 0; index < 6; index += 1) {
      label.write(alphabet[_random.nextInt(alphabet.length)]);
    }
    return label.toString();
  }
}