import 'dart:convert';
import 'package:http/http.dart' as http;

class ApiClient {
  ApiClient(
    this.baseUrl, {
    this.getAccessToken,
    this.onUnauthorized,
  });

  final String baseUrl; // z.B. https://api.windesign.at/hedgehogs.php?r=
  final Future<String?> Function()? getAccessToken;
  final Future<void> Function()? onUnauthorized;

  Future<http.Response> _send(String method, String path,
      {Object? body}) async {
    final uri = Uri.parse('$baseUrl$path');
    final headers = {'Content-Type': 'application/json'};
    final token = await getAccessToken?.call();
    if (token != null) headers['Authorization'] = 'Bearer $token';

    switch (method) {
      case 'GET':
        return http.get(uri, headers: headers);
      case 'POST':
        return http.post(uri,
            headers: headers, body: body == null ? null : jsonEncode(body));
      case 'PUT':
        return http.put(uri,
            headers: headers, body: body == null ? null : jsonEncode(body));
      case 'DELETE':
        return http.delete(uri, headers: headers);
      default:
        throw UnimplementedError(method);
    }
  }

  Future<T> _requestWithRetry<T>(String method, String path,
      {Object? body}) async {
    var res = await _send(method, path, body: body);

    if (res.statusCode == 401 && onUnauthorized != null) {
      await onUnauthorized!.call();
      res = await _send(method, path, body: body);
    }

    if (res.statusCode >= 200 && res.statusCode < 300) {
      if (res.body.isEmpty) return (null as T);
      final decoded = jsonDecode(res.body);
      return decoded as T;
    }
    throw ApiException(res.statusCode, res.body);
  }

  Future<T> get<T>(String path) async => _requestWithRetry<T>('GET', path);
  Future<T> post<T>(String path, Object body) async =>
      _requestWithRetry<T>('POST', path, body: body);
  Future<T> put<T>(String path, Object body) async =>
      _requestWithRetry<T>('PUT', path, body: body);
  Future<T> delete<T>(String path) async =>
      _requestWithRetry<T>('DELETE', path);
}

class ApiException implements Exception {
  final int status;
  final String body;
  ApiException(this.status, this.body);
  @override
  String toString() => 'ApiException($status): $body';
}