import 'dart:convert';

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

import '../config/intra_config.dart';

/// OAuth2 Intra : un token réutilisé pour toutes les requêtes API.
class IntraAuthService {
  IntraAuthService._();
  static final IntraAuthService instance = IntraAuthService._();

  final FlutterAppAuth _appAuth = const FlutterAppAuth();

  String? _accessToken;

  String? get accessToken => _accessToken;
  bool get isAuthenticated => _accessToken != null && _accessToken!.isNotEmpty;

  static final AuthorizationServiceConfiguration _serviceConfiguration =
      AuthorizationServiceConfiguration(
    authorizationEndpoint: IntraConfig.authorizeUrl,
    tokenEndpoint: IntraConfig.tokenUrl,
  );

  Future<void> signIn() async {
    if (!IntraConfig.isConfigured) {
      throw StateError(
        'CLIENT_ID, CLIENT_SECRET ou REDIRECT_URI manquant dans .env',
      );
    }

    final result = await _appAuth.authorizeAndExchangeCode(
      AuthorizationTokenRequest(
        IntraConfig.clientId,
        IntraConfig.redirectUri,
        clientSecret: IntraConfig.clientSecret,
        serviceConfiguration: _serviceConfiguration,
        // `projects` requis pour projects_users ; skills via cursus_users (pas /experiences).
        scopes: ['public', 'projects'],
      ),
    );

    _accessToken = result.accessToken;

    if (!isAuthenticated) {
      throw StateError('Connexion 42 annulée ou token absent');
    }
  }

  void signOut() {
    _accessToken = null;
  }

  /// Header Authorization pour les appels `api.intra.42.fr`.
  Map<String, String> authHeaders() {
    if (!isAuthenticated) {
      throw StateError('Non connecté à l’Intra');
    }
    return {
      'Authorization': 'Bearer $_accessToken',
      'Accept': 'application/json',
    };
  }

  Future<Map<String, dynamic>> fetchMe() async {
    final response = await http.get(
      Uri.parse('${IntraConfig.apiBaseUrl}/me'),
      headers: authHeaders(),
    );

    if (response.statusCode != 200) {
      throw Exception('GET /v2/me a échoué (${response.statusCode})');
    }

    return jsonDecode(response.body) as Map<String, dynamic>;
  }
}