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 clientConfigDevice = 'h5';
  static const String clientConfigSerialNo = 'h5-domain';
  static const String _dartDefinedH5LineUrls =
      String.fromEnvironment('H5_LINE_URLS');
  static const String _dartDefinedClientConfigQueryUrl =
      String.fromEnvironment('CLIENT_CONFIG_QUERY_URL');
  // Bootstrap only: used before /client_config/query returns dynamic H5 domains.
  static const String _bootstrapH5LineUrl = String.fromEnvironment(
      'BOOTSTRAP_H5_LINE_URL',
      defaultValue: 'https://h5-test.imharry.work/');
  static const Environment currentEnvironment = Environment.production;
  // Compatibility for the packaging service's legacy domain rewrite step.
  static final Map<Environment, List<String>> _environmentHosts = {
    Environment.production: [
      _bootstrapH5LineUrl,
    ],
  };
  static final Random _wildcardRandom = Random.secure();

  static List<H5Line> get h5Lines {
    final configuredUrls = _dartDefinedH5LineUrls.trim().isEmpty
        ? _normalizedUniqueUrls(defaultH5LineUrlsForBaseUri(Uri.base))
        : _normalizedUniqueUrls(_dartDefinedH5LineUrls.split(','));
    final urls = configuredUrls.isEmpty
        ? _normalizedUniqueUrls(const [_bootstrapH5LineUrl])
        : configuredUrls;

    return [
      for (var index = 0; index < urls.length; index += 1)
        H5Line(label: '线路${index + 1}', url: urls[index]),
    ];
  }

  static Map<String, String> get clientConfigQueryPayload => const {
        'device': clientConfigDevice,
        'serialNo': clientConfigSerialNo,
      };

  static List<Uri> get clientConfigQueryUris {
    final dartDefinedUrl = _dartDefinedClientConfigQueryUrl.trim();
    if (dartDefinedUrl.isNotEmpty) {
      return [Uri.parse(dartDefinedUrl)];
    }

    final lines = h5Lines;
    if (lines.isEmpty) {
      return const [];
    }

    return clientConfigQueryUrisForHomeUri(lines.first.uri);
  }

  static List<String> defaultH5LineUrlsForBaseUri(Uri baseUri) {
    final runtimeHomeUrl = _runtimeHomeUrlFromBaseUri(baseUri);
    if (runtimeHomeUrl != null) {
      return [runtimeHomeUrl];
    }

    final environmentHosts = _environmentHosts[currentEnvironment];
    if (environmentHosts == null || environmentHosts.isEmpty) {
      return const [_bootstrapH5LineUrl];
    }
    return environmentHosts;
  }

  static List<Uri> clientConfigQueryUrisForHomeUri(Uri homeUri) {
    return [
      _originUriWithPath(homeUri, '/client_config/query'),
      _originUriWithPath(homeUri, '/api/user/client_config/query'),
    ];
  }

  static List<H5Line> h5LinesFromResourceUrl(
    String resourceUrl, {
    String Function()? wildcardFactory,
  }) {
    final urls = _normalizedUniqueUrls(
      splitResourceUrlLines(resourceUrl).map(
        (value) => _replaceWildcardHost(
          value,
          wildcardFactory: wildcardFactory,
        ),
      ),
    );

    return [
      for (var index = 0; index < urls.length; index += 1)
        H5Line(label: '线路${index + 1}', url: urls[index]),
    ];
  }

  static List<String> splitResourceUrlLines(String resourceUrl) {
    if (resourceUrl.trim().isEmpty) {
      return const [];
    }

    final lines = <String>[];
    final seen = <String>{};
    for (final value
        in resourceUrl.split(RegExp(r'\\r\\n|\\n|\\r|\\t|[\r\n\t]+'))) {
      final line = value.trim();
      if (line.isEmpty || seen.contains(line)) {
        continue;
      }
      lines.add(line);
      seen.add(line);
    }
    return List.unmodifiable(lines);
  }

  static bool isLoginPageUrl(String? url) {
    if (url == null || url.isEmpty) {
      return false;
    }

    final uri = Uri.tryParse(url);
    if (uri == null) {
      return false;
    }

    return _isLoginPath(uri.path) || _isLoginPath(uri.fragment);
  }

  static bool _isLoginPath(String path) {
    final normalized = path.trim();
    if (normalized.isEmpty) {
      return false;
    }

    final pathOnly = normalized.split('?').first.split('#').first;
    final segments = pathOnly.split('/').where((segment) => segment.isNotEmpty);
    if (segments.isEmpty) {
      return false;
    }

    return segments.last == 'login';
  }

  static List<String> _normalizedUniqueUrls(Iterable<String> values) {
    final urls = <String>[];
    final seen = <String>{};

    for (final value in values) {
      final normalized = _tryNormalizeHomeUrl(value);
      if (normalized == null || seen.contains(normalized)) {
        continue;
      }
      urls.add(normalized);
      seen.add(normalized);
    }

    return List.unmodifiable(urls);
  }

  static String? _tryNormalizeHomeUrl(String value) {
    try {
      return _normalizeHomeUrl(value);
    } catch (_) {
      return null;
    }
  }

  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? _runtimeHomeUrlFromBaseUri(Uri baseUri) {
    if (_isLocalRuntimeUri(baseUri)) {
      return null;
    }

    return _originUriWithPath(baseUri, '/').toString();
  }

  static Uri _originUriWithPath(Uri uri, String path) {
    final normalizedPath = path.startsWith('/') ? path : '/$path';
    return Uri.parse('${uri.scheme}://${uri.authority}$normalizedPath');
  }

  static bool _isLocalRuntimeUri(Uri uri) {
    if (uri.scheme != 'http' && uri.scheme != 'https') {
      return true;
    }

    final host = _normalizeHostForCompare(uri.host);
    if (host.isEmpty) {
      return true;
    }

    if (host == 'localhost' || host.endsWith('.localhost') || host == '::1') {
      return true;
    }

    final ipv4Parts = _tryParseIpv4Address(host);
    if (ipv4Parts == null) {
      return false;
    }

    return ipv4Parts[0] == 127 || ipv4Parts.every((part) => part == 0);
  }

  static String _normalizeHostForCompare(String host) {
    final normalized = host.trim().toLowerCase();
    if (normalized.endsWith('.')) {
      return normalized.substring(0, normalized.length - 1);
    }
    return normalized;
  }

  static List<int>? _tryParseIpv4Address(String host) {
    final parts = host.split('.');
    if (parts.length != 4) {
      return null;
    }

    final octets = <int>[];
    for (final part in parts) {
      if (part.isEmpty || !RegExp(r'^\d+$').hasMatch(part)) {
        return null;
      }
      final value = int.tryParse(part);
      if (value == null || value < 0 || value > 255) {
        return null;
      }
      octets.add(value);
    }
    return octets;
  }

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

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

  static String _randomWildcardLabel() {
    const chars = 'abcdefghijklmnopqrstuvwxyz0123456789';
    return String.fromCharCodes(
      List<int>.generate(
        16,
        (_) => chars.codeUnitAt(_wildcardRandom.nextInt(chars.length)),
      ),
    );
  }
}