import 'package:freezed_annotation/freezed_annotation.dart';
import 'package:shuffle/features/auth/domain/auth_failure.dart';
import 'package:shuffle/features/auth/domain/validation/email_format.dart';

part 'login_state.freezed.dart';

/// Form fields of the sign-in, in reading order.
enum LoginField { email, password }

enum LoginStatus { editing, submitting }

/// Values, visibility of field errors and submit state of the sign-in form.
///
/// Credential failures are never attached to a field (Kriterium 7): they
/// show as [bannerFailure] above the form.
@freezed
abstract class LoginState with _$LoginState {
  const factory LoginState({
    @Default('') String email,
    @Default('') String password,
    @Default(<LoginField>{}) Set<LoginField> visibleFields,
    @Default(LoginStatus.editing) LoginStatus status,

    /// Failure of the last attempt, shown as banner.
    AuthFailure? bannerFailure,

    /// Address of the last attempt that ended in `emailNotConfirmed`. The
    /// resend action uses this one, not whatever is in the field now.
    String? unconfirmedEmail,

    /// Field that should receive focus after a failed submit.
    LoginField? focusField,

    /// Incremented whenever [focusField] is set.
    @Default(0) int focusRequest,
  }) = _LoginState;

  const LoginState._();

  bool get isSubmitting => status == LoginStatus.submitting;

  EmailError? get emailError => EmailFormat.validate(email);

  bool get passwordMissing => password.isEmpty;

  bool hasError(LoginField field) => switch (field) {
    LoginField.email => emailError != null,
    LoginField.password => passwordMissing,
  };

  LoginField? get firstInvalidField {
    for (final field in LoginField.values) {
      if (hasError(field)) {
        return field;
      }
    }
    return null;
  }

  bool isVisible(LoginField field) => visibleFields.contains(field);

  bool get shownEmailError => isVisible(LoginField.email) && emailError != null;

  bool get shownPasswordRequired =>
      isVisible(LoginField.password) && passwordMissing;

  bool get showsNotConfirmed =>
      bannerFailure is EmailNotConfirmed && unconfirmedEmail != null;
}