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

const String _baseUrl = 'https://backend.prosapp.co/api/v1';

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

class ApiService {
  static ApiService? _instance;
  static ApiService get instance => _instance ??= ApiService._();
  ApiService._();

  String? _token;

  Future<String?> getToken() async {
    if (_token != null) return _token;
    final prefs = await SharedPreferences.getInstance();
    _token = prefs.getString('token');
    return _token;
  }

  Future<void> saveToken(String token) async {
    _token = token;
    final prefs = await SharedPreferences.getInstance();
    await prefs.setString('token', token);
  }

  Future<void> clearToken() async {
    _token = null;
    final prefs = await SharedPreferences.getInstance();
    await prefs.remove('token');
  }

  Future<Map<String, String>> _headers({bool auth = true}) async {
    final headers = <String, String>{'Content-Type': 'application/json'};
    if (auth) {
      final token = await getToken();
      if (token != null) headers['Authorization'] = 'Bearer $token';
    }
    return headers;
  }

  dynamic _parse(http.Response res) {
    final body = jsonDecode(res.body);
    if (res.statusCode >= 200 && res.statusCode < 300) return body;
    final msg = body is Map ? (body['message'] ?? res.reasonPhrase) : res.reasonPhrase;
    throw ApiException(res.statusCode, msg.toString());
  }

  Future<dynamic> get(String path, {bool auth = true, Map<String, String>? query}) async {
    final uri = Uri.parse('$_baseUrl$path').replace(queryParameters: query);
    final res = await http.get(uri, headers: await _headers(auth: auth));
    return _parse(res);
  }

  Future<dynamic> post(String path, Map<String, dynamic> body, {bool auth = false}) async {
    final res = await http.post(
      Uri.parse('$_baseUrl$path'),
      headers: await _headers(auth: auth),
      body: jsonEncode(body),
    );
    return _parse(res);
  }

  Future<dynamic> patch(String path, Map<String, dynamic> body, {bool auth = true}) async {
    final res = await http.patch(
      Uri.parse('$_baseUrl$path'),
      headers: await _headers(auth: auth),
      body: jsonEncode(body),
    );
    return _parse(res);
  }

  Future<String> uploadFile(String filePath) async {
    final token = await getToken();
    final req = http.MultipartRequest('POST', Uri.parse('$_baseUrl/storage/upload'));
    if (token != null) req.headers['Authorization'] = 'Bearer $token';
    req.files.add(await http.MultipartFile.fromPath('file', filePath));
    final streamed = await req.send();
    final res = await http.Response.fromStream(streamed);
    final body = jsonDecode(res.body);
    if (res.statusCode >= 200 && res.statusCode < 300) return body['url'] as String;
    throw ApiException(res.statusCode, body['message']?.toString() ?? 'Upload failed');
  }
}