import 'dart:convert';
import 'package:dio/dio.dart';
import 'package:worldhopper/models/opds_server.dart';

/// Service for handling HTTP Basic Authentication
class AuthService {
  /// Create Dio client with authentication for a server
  Dio createAuthenticatedClient(OPDSServer server) {
    final dio = Dio(
      BaseOptions(
        connectTimeout: const Duration(seconds: 30),
        receiveTimeout: const Duration(seconds: 30),
        headers: {
          'User-Agent': 'Worldhopper/1.0',
          'Accept': 'application/atom+xml, application/xml, text/xml, */*',
        },
      ),
    );

    // Add authentication interceptor if credentials are provided
    if (server.requiresAuth) {
      dio.interceptors.add(
        InterceptorsWrapper(
          onRequest: (options, handler) {
            final authHeader = _generateBasicAuthHeader(
              server.username!,
              server.password!,
            );
            options.headers['Authorization'] = authHeader;
            return handler.next(options);
          },
          onError: (error, handler) {
            // Handle 401 Unauthorized errors
            if (error.response?.statusCode == 401) {
              // Could trigger re-authentication flow here
            }
            return handler.next(error);
          },
        ),
      );
    }

    // Add logging interceptor for debugging
    dio.interceptors.add(
      LogInterceptor(
        requestBody: false,
        responseBody: false,
        logPrint: (obj) {
          // Custom logging (can be integrated with a logging package)
          // print(obj);
        },
      ),
    );

    return dio;
  }

  /// Generate HTTP Basic Auth header
  String _generateBasicAuthHeader(String username, String password) {
    final credentials = '$username:$password';
    final encoded = base64Encode(utf8.encode(credentials));
    return 'Basic $encoded';
  }

  /// Get authentication headers for image requests
  Map<String, String> getAuthHeaders(OPDSServer server) {
    if (!server.requiresAuth) {
      return {};
    }

    return {
      'Authorization': _generateBasicAuthHeader(
        server.username!,
        server.password!,
      ),
    };
  }

  /// Generate Basic Auth header from username and password
  static String generateBasicAuthHeader(String username, String password) {
    final credentials = '$username:$password';
    final encoded = base64Encode(utf8.encode(credentials));
    return 'Basic $encoded';
  }
}