import 'dart:convert';

import 'package:crypto/crypto.dart';

class BackendIdentity {
  BackendIdentity._();

  static const internalBuild = bool.fromEnvironment('INTERNAL_BUILD');
  static const configuredBaseUrl = String.fromEnvironment('API_BASE_URL');

  static const String baseUrl = configuredBaseUrl != ''
      ? configuredBaseUrl
      : 'https://api.invalid';

  static final String scope = scopeForBaseUrl(baseUrl);

  static String accountNamespace(int userId) => 'account_${scope}_$userId';

  static String scopeForBaseUrl(String value) => sha256
      .convert(utf8.encode(_normalizedBaseUrl(value)))
      .toString()
      .substring(0, 16);

  static String accountNamespaceFor(String baseUrl, int userId) =>
      'account_${scopeForBaseUrl(baseUrl)}_$userId';

  static String _normalizedBaseUrl(String value) {
    final uri = Uri.tryParse(value.trim());
    if (uri == null || !uri.hasScheme || uri.host.isEmpty) {
      return value.trim().toLowerCase();
    }
    final path = uri.path == '/'
        ? ''
        : uri.path.replaceFirst(RegExp(r'/+$'), '');
    return uri
        .replace(path: path, query: null, fragment: null)
        .toString()
        .toLowerCase();
  }
}