import 'dart:async';

import 'package:flutter/material.dart';
import 'package:flutter/services.dart';
import 'package:flutter_riverpod/flutter_riverpod.dart';
import 'package:go_router/go_router.dart';
import 'package:shuffle/core/l10n/l10n.dart';
import 'package:shuffle/core/routing/app_routes.dart';
import 'package:shuffle/core/theme/app_spacing.dart';
import 'package:shuffle/core/widgets/app_banner.dart';
import 'package:shuffle/core/widgets/app_form_scaffold.dart';
import 'package:shuffle/core/widgets/app_password_field.dart';
import 'package:shuffle/core/widgets/app_primary_button.dart';
import 'package:shuffle/core/widgets/app_text_field.dart';
import 'package:shuffle/features/auth/domain/auth_failure.dart';
import 'package:shuffle/features/auth/presentation/auth_failure_texts.dart';
import 'package:shuffle/features/auth/presentation/check_email/resend_controller.dart';
import 'package:shuffle/features/auth/presentation/login/login_controller.dart';
import 'package:shuffle/features/auth/presentation/login/login_state.dart';
import 'package:shuffle/features/auth/presentation/widgets/auth_screen_title.dart';

/// Sign-in (`/login`, KTO-01 Kriterien 5, 6 und 7). Only shows state and
/// forwards input to the [LoginController]. [from] is the unchecked `from`
/// query parameter; the controller validates it.
class LoginScreen extends ConsumerStatefulWidget {
  const LoginScreen({this.from, super.key});

  final String? from;

  @override
  ConsumerState<LoginScreen> createState() => _LoginScreenState();
}

class _LoginScreenState extends ConsumerState<LoginScreen> {
  final _email = TextEditingController();
  final _password = TextEditingController();
  final _emailFocus = FocusNode();
  final _passwordFocus = FocusNode();

  @override
  void initState() {
    super.initState();
    _emailFocus.addListener(
      () => _onFocusChange(_emailFocus, LoginField.email),
    );
    _passwordFocus.addListener(
      () => _onFocusChange(_passwordFocus, LoginField.password),
    );
  }

  void _onFocusChange(FocusNode node, LoginField field) {
    if (!node.hasFocus) {
      ref.read(loginControllerProvider.notifier).fieldBlurred(field);
    }
  }

  @override
  void dispose() {
    _email.dispose();
    _password.dispose();
    _emailFocus.dispose();
    _passwordFocus.dispose();
    super.dispose();
  }

  Future<void> _submit() async {
    final target = await ref
        .read(loginControllerProvider.notifier)
        .submit(from: widget.from);
    if (!mounted || target == null) {
      return;
    }
    TextInput.finishAutofillContext();
    context.go(target);
  }

  void _requestFocus(LoginField? field) {
    switch (field) {
      case LoginField.email:
        _emailFocus.requestFocus();
      case LoginField.password:
        _passwordFocus.requestFocus();
      case null:
        break;
    }
  }

  @override
  Widget build(BuildContext context) {
    ref.listen(loginControllerProvider, (previous, next) {
      if (previous?.focusRequest != next.focusRequest) {
        _requestFocus(next.focusField);
      }
    });
    final state = ref.watch(loginControllerProvider);
    final resend = ref.watch(resendControllerProvider);
    final controller = ref.read(loginControllerProvider.notifier);
    final l10n = context.l10n;
    final busy = state.isSubmitting;

    return AppFormScaffold(
      key: const Key('login_screen'),
      child: AutofillGroup(
        child: Column(
          crossAxisAlignment: CrossAxisAlignment.stretch,
          children: [
            AuthScreenTitle(l10n.authLoginTitle),
            if (state.bannerFailure case final failure?) ...[
              const SizedBox(height: AppSpacing.lg),
              if (state.showsNotConfirmed)
                AppBanner(
                  key: const Key('login_not_confirmed_banner'),
                  type: AppBannerType.info,
                  typeLabel: l10n.authBannerTypeInfo,
                  message: l10n.authErrorEmailNotConfirmed,
                  actionLabel: resend.isSending
                      ? null
                      : l10n.authActionResendConfirmation,
                  onAction: resend.isSending
                      ? null
                      : () => unawaited(controller.resendConfirmation()),
                )
              else
                _FailureBanner(
                  key: const Key('login_banner'),
                  failure: failure,
                  onRetry: busy ? null : _submit,
                ),
            ],
            if (state.showsNotConfirmed && resend.sent) ...[
              const SizedBox(height: AppSpacing.md),
              AppBanner(
                key: const Key('login_resent_banner'),
                type: AppBannerType.info,
                typeLabel: l10n.authBannerTypeInfo,
                message: l10n.authCheckEmailResent,
              ),
            ],
            if (state.showsNotConfirmed && resend.failure != null) ...[
              const SizedBox(height: AppSpacing.md),
              AppBanner(
                key: const Key('login_resend_error_banner'),
                type: AppBannerType.error,
                typeLabel: l10n.authBannerTypeError,
                message: authFailureMessage(l10n, resend.failure!),
              ),
            ],
            const SizedBox(height: AppSpacing.xl),
            AppTextField(
              key: const Key('login_email'),
              label: l10n.authFieldEmailLabel,
              controller: _email,
              focusNode: _emailFocus,
              keyboardType: TextInputType.emailAddress,
              textInputAction: TextInputAction.next,
              autofillHints: const [
                AutofillHints.username,
                AutofillHints.email,
              ],
              autocorrect: false,
              enableSuggestions: false,
              enabled: !busy,
              errorText: state.shownEmailError
                  ? l10n.authErrorEmailInvalid
                  : null,
              onChanged: controller.emailChanged,
            ),
            const SizedBox(height: AppSpacing.lg),
            AppPasswordField(
              key: const Key('login_password'),
              label: l10n.authFieldPasswordLabel,
              showPasswordLabel: l10n.authPasswordShow,
              hidePasswordLabel: l10n.authPasswordHide,
              controller: _password,
              focusNode: _passwordFocus,
              textInputAction: TextInputAction.done,
              enabled: !busy,
              errorText: state.shownPasswordRequired
                  ? l10n.authPasswordRequired
                  : null,
              onChanged: controller.passwordChanged,
              onSubmitted: (_) {
                if (!busy) {
                  unawaited(_submit());
                }
              },
            ),
            const SizedBox(height: AppSpacing.xl),
            AppPrimaryButton(
              key: const Key('login_submit'),
              label: l10n.authLoginSubmit,
              loadingLabel: l10n.authSubmitting,
              isLoading: busy,
              onPressed: _submit,
            ),
            const SizedBox(height: AppSpacing.sm),
            TextButton(
              key: const Key('login_forgot_link'),
              onPressed: busy
                  ? null
                  : () => context.go(AppRoutes.forgotPassword),
              child: Text(l10n.authLoginForgotPassword),
            ),
            TextButton(
              key: const Key('login_register_link'),
              onPressed: busy ? null : () => context.go(AppRoutes.register),
              child: Text(l10n.authLoginCreateAccount),
            ),
          ],
        ),
      ),
    );
  }
}

class _FailureBanner extends StatelessWidget {
  const _FailureBanner({
    required this.failure,
    required this.onRetry,
    super.key,
  });

  final AuthFailure failure;
  final VoidCallback? onRetry;

  @override
  Widget build(BuildContext context) {
    final l10n = context.l10n;
    final retryable = failure is NetworkFailure || failure is Unexpected;
    return AppBanner(
      type: AppBannerType.error,
      typeLabel: l10n.authBannerTypeError,
      message: authFailureMessage(l10n, failure),
      actionLabel: retryable && onRetry != null ? l10n.authActionRetry : null,
      onAction: retryable ? onRetry : null,
    );
  }
}