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

import 'api_client.dart';

final sessionProvider = AsyncNotifierProvider<SessionNotifier, SessionData?>(
  SessionNotifier.new,
);

class SessionData {
  const SessionData({
    required this.userId,
    required this.email,
    this.defaultContextId,
    this.selectedContextId,
  });

  final String userId;
  final String email;
  final String? defaultContextId;
  final String? selectedContextId;

  String? get effectiveContextId => selectedContextId ?? defaultContextId;
}

class SessionNotifier extends AsyncNotifier<SessionData?> {
  static const _kContext = 'msn_selected_context_id';

  @override
  Future<SessionData?> build() async {
    final storage = ref.read(tokenStorageProvider);
    final token = await storage.readToken();
    if (token == null || token.isEmpty) return null;

    final dio = ref.read(dioProvider);
    try {
      final res = await dio.get<Map<String, dynamic>>('/api/auth/me');
      final id = res.data!['id'] as String;
      final email = res.data!['email'] as String;
      final prefs = await SharedPreferences.getInstance();
      final saved = prefs.getString(_kContext);
      final ctxRes = await dio.get<Map<String, dynamic>>('/api/contexts');
      final list = ctxRes.data!['contexts'] as List<dynamic>? ?? [];
      String? personalId;
      for (final c in list) {
        final m = c as Map<String, dynamic>;
        if (m['kind'] == 'personal') {
          personalId = m['id'] as String;
          break;
        }
      }
      final def = personalId ?? (list.isNotEmpty ? (list.first as Map)['id'] as String : null);
      return SessionData(
        userId: id,
        email: email,
        defaultContextId: def,
        selectedContextId: saved ?? def,
      );
    } on DioException {
      await storage.clear();
      return null;
    }
  }

  Future<void> applyLogin({
    required String userId,
    required String email,
    String? defaultContextId,
  }) async {
    final prefs = await SharedPreferences.getInstance();
    final saved = prefs.getString(_kContext);
    state = AsyncData(
      SessionData(
        userId: userId,
        email: email,
        defaultContextId: defaultContextId,
        selectedContextId: saved ?? defaultContextId,
      ),
    );
  }

  Future<void> setSelectedContext(String contextId) async {
    final cur = state.value;
    if (cur == null) return;
    final prefs = await SharedPreferences.getInstance();
    await prefs.setString(_kContext, contextId);
    state = AsyncData(
      SessionData(
        userId: cur.userId,
        email: cur.email,
        defaultContextId: cur.defaultContextId,
        selectedContextId: contextId,
      ),
    );
  }

  Future<void> logout() async {
    await ref.read(tokenStorageProvider).clear();
    final prefs = await SharedPreferences.getInstance();
    await prefs.remove(_kContext);
    state = const AsyncData(null);
  }
}