import 'dart:async';

import 'package:riverpod_annotation/riverpod_annotation.dart';
import 'package:shuffle/core/config/app_config_provider.dart';
import 'package:shuffle/core/logging/app_logger.dart';
import 'package:shuffle/core/platform/url_opener.dart';
import 'package:shuffle/features/auth/domain/auth_failure.dart';
import 'package:shuffle/features/auth/domain/resend_origin.dart';
import 'package:shuffle/features/auth/domain/validation/display_name_rule.dart';
import 'package:shuffle/features/auth/domain/validation/email_format.dart';
import 'package:shuffle/features/auth/presentation/providers/auth_providers.dart';
import 'package:shuffle/features/auth/presentation/register/register_state.dart';

part 'register_controller.g.dart';

/// Legal texts linked from the consent checkbox.
enum LegalDocument { privacy, terms }

final _log = AppLogger('RegisterController');

/// Logic of the registration form (KTO-01 Kriterien 1 bis 4 und 10).
@riverpod
class RegisterController extends _$RegisterController {
  Future<void>? _commonPasswordsLoad;

  @override
  RegisterState build() => const RegisterState();

  void emailChanged(String value) {
    state = state.copyWith(email: value, serverEmailInvalid: false);
  }

  void passwordChanged(String value) {
    // The password is checked while typing (Kriterium 3).
    state = state.copyWith(
      password: value,
      visibleFields: {...state.visibleFields, RegisterField.password},
      serverPasswordReasons: null,
    );
    unawaited(loadCommonPasswords());
  }

  void displayNameChanged(String value) {
    state = state.copyWith(displayName: value);
  }

  void ageConfirmedChanged({required bool value}) {
    state = state.copyWith(ageConfirmed: value);
  }

  void termsAcceptedChanged({required bool value}) {
    state = state.copyWith(termsAccepted: value);
  }

  /// Field left: show its error (text fields only).
  void fieldBlurred(RegisterField field) {
    if (field == RegisterField.ageConfirmation ||
        field == RegisterField.termsAcceptance) {
      return;
    }
    state = state.copyWith(visibleFields: {...state.visibleFields, field});
  }

  /// Starts loading the list of common passwords (lazy, once). Called when
  /// the password field is used.
  Future<void> loadCommonPasswords() => _commonPasswordsLoad ??= _load();

  Future<void> _load() async {
    try {
      final list = await ref.read(commonPasswordListProvider.future);
      if (!ref.mounted) {
        return;
      }
      state = state.copyWith(commonPasswords: list);
    } on Object catch (error) {
      // Fallback: only the length rule runs in the client; the server
      // enforces the minimum length as well.
      _log.warning('common password list unavailable: ${error.runtimeType}');
    }
  }

  /// Validates and submits. Returns `true` if the screen should continue to
  /// "check your inbox" (every 200 response, and `emailSendLimited`, F12).
  Future<bool> submit() async {
    if (state.isSubmitting) {
      return false;
    }
    // Set before the first await, otherwise a second trigger (button and
    // Enter key) passes the guard while the list is still loading.
    state = state.copyWith(status: RegisterStatus.submitting);
    await loadCommonPasswords();
    if (!ref.mounted) {
      return false;
    }

    state = state.copyWith(
      visibleFields: RegisterField.values.toSet(),
      bannerFailure: null,
      serverPasswordReasons: null,
      serverEmailInvalid: false,
      focusField: null,
    );
    final invalid = state.firstInvalidField;
    if (invalid != null) {
      state = state.copyWith(
        status: RegisterStatus.editing,
        focusField: invalid,
        focusRequest: state.focusRequest + 1,
      );
      return false;
    }

    final input = ref.read(registrationInputFactoryProvider)(
      email: EmailFormat.normalize(state.email),
      password: state.password,
      displayName: DisplayNameRule.normalize(state.displayName),
      ageConfirmed: state.ageConfirmed,
      termsAccepted: state.termsAccepted,
    );
    final result = await ref.read(authRepositoryProvider).signUp(input);
    if (!ref.mounted) {
      return false;
    }

    final failure = result.errorOrNull;
    state = state.copyWith(status: RegisterStatus.editing);
    if (failure == null || openEmailInputFailureFor(failure) == null) {
      return true;
    }
    _showFailure(failure);
    return false;
  }

  void _showFailure(AuthFailure failure) {
    switch (failure) {
      case WeakPassword(:final reasons):
        state = state.copyWith(
          serverPasswordReasons: reasons,
          focusField: RegisterField.password,
          focusRequest: state.focusRequest + 1,
        );
      case InvalidEmail():
        state = state.copyWith(
          serverEmailInvalid: true,
          focusField: RegisterField.email,
          focusRequest: state.focusRequest + 1,
        );
      default:
        state = state.copyWith(bannerFailure: failure);
    }
  }

  /// Opens a legal text in the browser. `false` if that did not work.
  Future<bool> openLegalDocument(LegalDocument document) async {
    final config = ref.read(appConfigProvider);
    final url = switch (document) {
      LegalDocument.privacy => config.legalPrivacyUrl,
      LegalDocument.terms => config.legalTermsUrl,
    };
    final uri = Uri.tryParse(url);
    if (uri == null || !isOpenableExternalUrl(uri)) {
      _log.warning('invalid legal url for ${document.name}');
      return false;
    }
    return ref.read(urlOpenerProvider)(uri);
  }
}