import 'dart:convert';

import 'package:shared_preferences/shared_preferences.dart';
import 'package:flutter/foundation.dart';
import 'package:uuid/uuid.dart';

/// Persists the user's profile (nickname, tagline, interests) and ephemeral BLE
/// token locally. No data is ever sent without explicit user consent (toggle).
class SessionStore extends ChangeNotifier {
  static const _interestsKey = 'interests';
  static const _tokenKey = 'ble_token';
  static const _nameKey = 'profile_name';
  static const _taglineKey = 'profile_tagline';
  static const _profileDoneKey = 'profile_done';

  List<String> _interests = [];
  String _bleToken = '';
  String _name = '';
  String _tagline = '';
  bool _profileDone = false;

  List<String> get interests => List.unmodifiable(_interests);
  String get bleToken => _bleToken;
  String get name => _name;
  String get tagline => _tagline;

  /// True once the user has completed profile setup at least once.
  bool get hasProfile => _profileDone;

  /// Display name — falls back to "Anonym" if not set.
  String get displayName => _name.isNotEmpty ? _name : 'Anonym';

  SessionStore() {
    _load();
  }

  Future<void> _load() async {
    final prefs = await SharedPreferences.getInstance();
    _interests = prefs.getStringList(_interestsKey) ?? [];
    _bleToken = prefs.getString(_tokenKey) ?? _newToken(prefs);
    _name = prefs.getString(_nameKey) ?? '';
    _tagline = prefs.getString(_taglineKey) ?? '';
    _profileDone = prefs.getBool(_profileDoneKey) ?? false;
    notifyListeners();
  }

  String _newToken(SharedPreferences prefs) {
    final token = const Uuid().v4();
    prefs.setString(_tokenKey, token);
    return token;
  }

  /// Saves the full profile in one call. Marks profile as complete.
  Future<void> saveProfile({
    required String name,
    required String tagline,
    required List<String> interests,
  }) async {
    final prefs = await SharedPreferences.getInstance();
    await Future.wait([
      prefs.setString(_nameKey, name),
      prefs.setString(_taglineKey, tagline),
      prefs.setStringList(_interestsKey, interests),
      prefs.setBool(_profileDoneKey, true),
    ]);
    _name = name;
    _tagline = tagline;
    _interests = interests;
    _profileDone = true;
    notifyListeners();
  }

  /// Reset ephemeral identity — fresh BLE token, clears profile.
  Future<void> reset() async {
    final prefs = await SharedPreferences.getInstance();
    await Future.wait([
      prefs.remove(_interestsKey),
      prefs.remove(_nameKey),
      prefs.remove(_taglineKey),
      prefs.remove(_profileDoneKey),
    ]);
    _interests = [];
    _name = '';
    _tagline = '';
    _profileDone = false;
    _bleToken = _newToken(prefs);
    notifyListeners();
  }
}