ai-contract-platform/mobile/lib/shared/storage/session_store.dart

import 'dart:convert';

import 'package:flutter/foundation.dart';
import 'package:flutter/services.dart';
import 'package:flutter_secure_storage/flutter_secure_storage.dart';
import 'package:shared_preferences/shared_preferences.dart';

import '../../features/auth/config/auth_config.dart';
import '../../features/auth/domain/auth_session.dart';

abstract class SessionStorageDriver {
  const SessionStorageDriver();

  Future<String?> read(String key);
  Future<void> write(String key, String value);
  Future<void> delete(String key);
}

class SecureSessionStorageDriver implements SessionStorageDriver {
  const SecureSessionStorageDriver();

  static const FlutterSecureStorage _storage = FlutterSecureStorage();

  @override
  Future<String?> read(String key) {
    return _storage.read(key: key);
  }

  @override
  Future<void> write(String key, String value) {
    return _storage.write(key: key, value: value);
  }

  @override
  Future<void> delete(String key) {
    return _storage.delete(key: key);
  }
}

class InMemorySessionStorageDriver implements SessionStorageDriver {
  InMemorySessionStorageDriver({Map<String, String>? initialValues})
    : _values = Map<String, String>.from(initialValues ?? const <String, String>{});

  final Map<String, String> _values;

  @override
  Future<String?> read(String key) async {
    return _values[key];
  }

  @override
  Future<void> write(String key, String value) async {
    _values[key] = value;
  }

  @override
  Future<void> delete(String key) async {
    _values.remove(key);
  }
}

class SessionStore {
  SessionStore._();

  static final ValueNotifier<AuthSession?> _current = ValueNotifier<AuthSession?>(null);
  static SessionStorageDriver _storage = const SecureSessionStorageDriver();

  static ValueListenable<AuthSession?> get listenable => _current;
  static AuthSession? get current => _current.value;
  static bool get isSignedIn => _current.value?.isAuthenticated ?? false;

  @visibleForTesting
  static void useStorageDriverForTesting(SessionStorageDriver storage) {
    _storage = storage;
    _current.value = null;
  }

  @visibleForTesting
  static void resetStorageDriverForTesting() {
    _storage = const SecureSessionStorageDriver();
    _current.value = null;
  }

  static Future<void> hydrate() async {
    if (!AuthConfig.persistSession) {
      return;
    }
    final raw = await _loadPersistedSession();
    if (raw == null || raw.isEmpty) {
      return;
    }
    try {
      final decoded = jsonDecode(raw);
      if (decoded is Map<String, dynamic>) {
        final session = AuthSession.fromJson(decoded);
        if (session.isAuthenticated) {
          _current.value = session;
        } else {
          _current.value = null;
          await _deletePersistedSession();
        }
      }
    } catch (_) {
      _current.value = null;
      await _deletePersistedSession();
    }
  }

  static Future<void> save(AuthSession session) async {
    _current.value = session;
    if (!AuthConfig.persistSession) {
      return;
    }
    await _storage.write(AuthConfig.sessionStorageKey, jsonEncode(session.toJson()));
    if (_storage is SecureSessionStorageDriver) {
      await _deleteLegacySession();
    }
  }

  static Future<void> clear() async {
    _current.value = null;
    if (!AuthConfig.persistSession) {
      return;
    }
    await _storage.delete(AuthConfig.sessionStorageKey);
    if (_storage is SecureSessionStorageDriver) {
      await _deleteLegacySession();
    }
  }

  static Future<String?> _loadPersistedSession() async {
    final raw = await _storage.read(AuthConfig.sessionStorageKey);
    if (raw != null && raw.isNotEmpty) {
      return raw;
    }

    try {
      final preferences = await SharedPreferences.getInstance();
      final legacyRaw = preferences.getString(AuthConfig.sessionStorageKey);
      if (legacyRaw == null || legacyRaw.isEmpty) {
        return null;
      }

      await _storage.write(AuthConfig.sessionStorageKey, legacyRaw);
      await preferences.remove(AuthConfig.sessionStorageKey);
      return legacyRaw;
    } on MissingPluginException {
      return null;
    }
  }

  static Future<void> _deletePersistedSession() async {
    await _storage.delete(AuthConfig.sessionStorageKey);
    await _deleteLegacySession();
  }

  static Future<void> _deleteLegacySession() async {
    try {
      final preferences = await SharedPreferences.getInstance();
      await preferences.remove(AuthConfig.sessionStorageKey);
    } on MissingPluginException {
      // Unit tests that use an in-memory driver do not register the legacy plugin.
    }
  }
}