import 'package:flutter/foundation.dart';

import '../models/verification.dart';
import '../services/verification.dart';

class VerificationProvider extends ChangeNotifier {
  VerificationProvider(this.service);
  final VerificationService service;
  VerificationState _state = const VerificationState(VerificationStatus.idle);
  VerificationState get state => _state;
  bool _disposed = false;
  int _generation = 0;

  Future<void> send({required String email, required String locale}) => _run(
    () => service.send(email: email.trim(), locale: locale),
    VerificationStatus.sending,
    VerificationStatus.sent,
  );
  Future<void> confirm(String token) => _run(
    () => service.confirm(token: token),
    VerificationStatus.checking,
    VerificationStatus.verified,
  );

  Future<void> _run(
    Future<VerificationResult> Function() operation,
    VerificationStatus loading,
    VerificationStatus success,
  ) async {
    if (_disposed || _state.isLoading) return;
    final generation = ++_generation;
    _state = VerificationState(loading);
    notifyListeners();
    if (_disposed || generation != _generation) return;
    try {
      final result = await operation();
      if (_disposed || generation != _generation) return;
      _state = VerificationState(
        success,
        isSimulated: result.isSimulated,
        result: success == VerificationStatus.verified ? result : null,
      );
    } catch (error) {
      if (_disposed || generation != _generation) return;
      final code = error is VerificationException
          ? error.code
          : VerificationError.internal;
      // Send failures must not be presented as confirmation-token failures.
      _state = VerificationState(
        loading == VerificationStatus.sending
            ? VerificationStatus.error
            : switch (code) {
                VerificationError.expired => VerificationStatus.expired,
                VerificationError.invalid => VerificationStatus.invalid,
                VerificationError.internal => VerificationStatus.error,
                VerificationError.needsAssistance => VerificationStatus.error,
              },
        error: code,
      );
    }
    notifyListeners();
  }

  void reset() {
    if (_disposed) return;
    ++_generation;
    _state = const VerificationState(VerificationStatus.idle);
    notifyListeners();
  }

  @override
  void dispose() {
    _disposed = true;
    ++_generation;
    super.dispose();
  }
}