import 'package:dio/dio.dart';
import 'package:fintracker_api/fintracker_api.dart';
import 'package:flutter_riverpod/flutter_riverpod.dart';

import '../cache/response_cache_provider.dart';
import '../config.dart';
import 'token_store.dart';

enum AuthStatus { unknown, signedOut, signedIn }

class AuthState {
  const AuthState(this.status, {this.accessToken, this.email});
  final AuthStatus status;
  final String? accessToken;
  final String? email;

  bool get signedIn => status == AuthStatus.signedIn;
}

final tokenStoreProvider = Provider<TokenStore>((_) => TokenStore());

/// A bare Dio for auth calls: no auth interceptor, so a refresh can never recurse.
final authDioProvider = Provider<Dio>(
  (ref) => Dio(
    BaseOptions(
      baseUrl: ref.watch(apiBaseUrlProvider),
      connectTimeout: const Duration(seconds: 10),
      receiveTimeout: const Duration(seconds: 20),
    ),
  ),
);

final authControllerProvider = NotifierProvider<AuthController, AuthState>(
  AuthController.new,
);

class AuthController extends Notifier<AuthState> {
  @override
  AuthState build() {
    Future.microtask(_restore);
    return const AuthState(AuthStatus.unknown);
  }

  AuthApi get _api => AuthApi(ref.read(authDioProvider));
  TokenStore get _store => ref.read(tokenStoreProvider);

  Future<void> _restore() async {
    final refresh = await _store.readRefresh();
    if (refresh == null) {
      state = const AuthState(AuthStatus.signedOut);
      return;
    }
    final ok = await refreshSession(refresh);
    if (!ok) state = const AuthState(AuthStatus.signedOut);
  }

  Future<String?> login(String email, String password) async {
    try {
      final r = await _api.authLogin(
        loginRequest: LoginRequest(email: email, password: password),
      );
      await _accept(r.data!);
      return null;
    } on DioException catch (e) {
      return problemMessage(e);
    }
  }

  /// Exchange a refresh token for a new pair. Returns false when it is no longer valid.
  Future<bool> refreshSession([String? refresh]) async {
    final token = refresh ?? await _store.readRefresh();
    if (token == null) return false;
    try {
      final r = await _api.authRefresh(
        refreshRequest: RefreshRequest(refreshToken: token),
      );
      await _accept(r.data!);
      return true;
    } on DioException catch (e) {
      if (e.response?.statusCode == 401) await _wipeLocal();
      return false;
    }
  }

  Future<void> _accept(TokenPair pair) async {
    await _store.writeRefresh(pair.refreshToken);
    state = AuthState(
      AuthStatus.signedIn,
      accessToken: pair.accessToken,
      email: state.email,
    );
  }

  Future<void> logout() async {
    final refresh = await _store.readRefresh();
    if (refresh != null) {
      try {
        await _api.authLogout(
          refreshRequest: RefreshRequest(refreshToken: refresh),
        );
      } on DioException {
        // the server may already consider it revoked; local state wins
      }
    }
    await _wipeLocal();
    state = const AuthState(AuthStatus.signedOut);
  }

  /// Everything this device keeps for the account: the refresh token and the cached
  /// responses (the whole financial picture, in plain sqlite / IndexedDB).
  Future<void> _wipeLocal() async {
    await _store.clear();
    try {
      await ref.read(responseCacheDbProvider).clear();
    } on Object {
      // the token is already gone; a cache that cannot be opened must not block signing out
    }
  }
}

/// Human-readable text from an RFC 7807 body, falling back to the transport error.
String problemMessage(DioException e) {
  final data = e.response?.data;
  if (data is Map) {
    final detail = data['detail'] ?? data['title'];
    if (detail is String && detail.isNotEmpty) return detail;
  }
  return switch (e.type) {
    DioExceptionType.connectionError ||
    DioExceptionType.connectionTimeout ||
    DioExceptionType.receiveTimeout => 'Сервер недоступен',
    _ => e.message ?? 'Ошибка запроса',
  };
}