import 'dart:async';

import 'package:flutter/material.dart';
import 'package:flutter_bloc/flutter_bloc.dart';

import '../../../../api/marianumcloud/cloud_users/cloud_users_actions.dart';
import '../../../../push/push_registration.dart';
import '../../../../routing/app_routes.dart';
import '../../../../session/account_codec.dart';
import '../../../../session/session.dart';
import '../../../../session/session_lifecycle.dart';
import '../../../../session/session_manager.dart';
import '../../../../state/app/modules/account/bloc/account_bloc.dart';
import '../../../../state/app/modules/capabilities/bloc/capabilities_cubit.dart';
import '../../../../widget/account_switcher_sheet.dart';
import '../../../../widget/app_progress_indicator.dart';
import '../../../../widget/async_action_button.dart';
import '../../../../widget/avatar_actions_sheet.dart';
import '../../../../widget/child_switcher.dart';
import '../../../../widget/confirm_dialog.dart';
import '../../../../widget/demo_restricted.dart';
import '../../../../widget/user_avatar.dart';

// Display-name is stable per account; cache it so every Settings rebuild
// doesn't re-issue the OCS request.
String? _cachedDisplayName;
String? _cachedDisplayNameFor;

class AccountSection extends StatelessWidget {
  const AccountSection({super.key});

  @override
  Widget build(BuildContext context) => switch (SessionManager().current) {
    GuardianSession(:final email) => _GuardianAccount(email: email),
    _ => const _SchoolAccount(),
  };
}

/// Guardians have no Nextcloud profile: show the e-mail and linked children.
class _GuardianAccount extends StatelessWidget {
  final String email;

  const _GuardianAccount({required this.email});

  @override
  Widget build(BuildContext context) {
    final children = context.watch<CapabilitiesCubit>().state.children;
    final colors = Theme.of(context).colorScheme;
    return Column(
      crossAxisAlignment: CrossAxisAlignment.stretch,
      children: [
        Padding(
          padding: const EdgeInsets.fromLTRB(16, 20, 8, 16),
          child: Row(
            children: [
              CircleAvatar(
                radius: 36,
                backgroundColor: colors.secondaryContainer,
                foregroundColor: colors.onSecondaryContainer,
                child: const Icon(Icons.family_restroom_outlined, size: 34),
              ),
              const SizedBox(width: 12),
              Expanded(
                child: ValueListenableBuilder<AccountIndex>(
                  valueListenable: SessionManager().accounts,
                  builder: (context, index, _) => _AccountName(
                    name: index.active?.displayName ?? 'Elternkonto',
                    identity: email,
                  ),
                ),
              ),
              const SizedBox(width: 4),
              const _AccountActions(),
            ],
          ),
        ),
        if (children.isNotEmpty)
          Padding(
            padding: const EdgeInsets.fromLTRB(16, 8, 16, 0),
            child: Text(
              children.length == 1 ? 'Dein Kind' : 'Deine Kinder',
              style: Theme.of(context).textTheme.labelLarge?.copyWith(
                color: Theme.of(context).colorScheme.primary,
              ),
            ),
          ),
        for (final child in children) ChildTile(child: child),
      ],
    );
  }
}

class _SchoolAccount extends StatefulWidget {
  const _SchoolAccount();

  @override
  State<_SchoolAccount> createState() => _SchoolAccountState();
}

class _SchoolAccountState extends State<_SchoolAccount> {
  int _avatarVersion = 0;
  bool _avatarBusy = false;
  String? _displayName;

  @override
  void initState() {
    super.initState();
    final username = SessionManager().requireNextcloud().username;
    if (_cachedDisplayNameFor == username) _displayName = _cachedDisplayName;
    if (_displayName == null) _loadDisplayName(username);
  }

  Future<void> _loadDisplayName(String username) async {
    try {
      final info = await GetUserInfo().run();
      _cachedDisplayNameFor = username;
      _cachedDisplayName = info.displayName.isEmpty ? null : info.displayName;
      if (!mounted) return;
      setState(() => _displayName = _cachedDisplayName);
    } catch (_) {
      // Silent fallback to username — surfacing an error dialog over the
      // settings screen on every open would be noisier than helpful.
    }
  }

  Future<void> _editAvatar() async {
    if (guardDemoAction(context)) return;
    final result = await showAvatarActionsSheet(context, allowRemove: true);
    if (result == null || !mounted) return;

    if (result is AvatarRemoveResult) {
      var confirmed = false;
      await showDialog<void>(
        context: context,
        builder: (_) => ConfirmDialog(
          title: 'Profilbild entfernen',
          content: 'Möchtest du dein Profilbild wirklich entfernen?',
          confirmButton: 'Entfernen',
          onConfirm: () => confirmed = true,
        ),
      );
      if (!confirmed || !mounted) return;
    }

    setState(() => _avatarBusy = true);
    final ok = await runWithErrorDialog(context, () async {
      if (result is AvatarUploadResult) {
        await SetUserAvatar(result.bytes).run();
      } else {
        await DeleteUserAvatar().run();
      }
    });
    if (!mounted) return;
    setState(() => _avatarBusy = false);
    if (!ok) return;

    invalidateAvatarCache(
      id: SessionManager().requireNextcloud().username,
      isGroup: false,
    );
    setState(() => _avatarVersion++);
  }

  @override
  Widget build(BuildContext context) {
    final nextcloud = SessionManager().requireNextcloud();
    final username = nextcloud.username;
    final displayName = _displayName;
    final theme = Theme.of(context);

    return Column(
      crossAxisAlignment: CrossAxisAlignment.stretch,
      children: [
        Padding(
          padding: const EdgeInsets.fromLTRB(16, 20, 8, 16),
          child: Row(
            children: [
              SizedBox(
                width: 84,
                height: 84,
                child: Stack(
                  clipBehavior: Clip.none,
                  children: [
                    Center(
                      child: GestureDetector(
                        onTap: () => AppRoutes.openLargeProfilePicture(
                          context,
                          username,
                        ),
                        child: UserAvatar(
                          key: ValueKey(_avatarVersion),
                          id: username,
                          size: 36,
                          requestSize: 256,
                        ),
                      ),
                    ),
                    Positioned(
                      right: 0,
                      bottom: 0,
                      child: _AvatarEditBadge(
                        busy: _avatarBusy,
                        onTap: _avatarBusy ? null : _editAvatar,
                      ),
                    ),
                  ],
                ),
              ),
              const SizedBox(width: 12),
              Expanded(
                child: Column(
                  crossAxisAlignment: CrossAxisAlignment.start,
                  mainAxisSize: MainAxisSize.min,
                  children: [
                    Text(
                      displayName ?? username,
                      style: const TextStyle(
                        fontSize: 20,
                        fontWeight: FontWeight.w600,
                      ),
                      maxLines: 2,
                      overflow: TextOverflow.ellipsis,
                    ),
                    if (displayName != null) ...[
                      const SizedBox(height: 2),
                      Text(
                        username,
                        style: TextStyle(
                          fontSize: 13,
                          color: theme.colorScheme.onSurfaceVariant,
                        ),
                        maxLines: 1,
                        overflow: TextOverflow.ellipsis,
                      ),
                    ],
                  ],
                ),
              ),
              const SizedBox(width: 4),
              const _AccountActions(),
            ],
          ),
        ),
        // Nur für Login-Flow-Konten (2FA) sichtbar — Passwort-Konten heilen
        // sich still über das App-Passwort-Minting und sollen von dem ganzen
        // Flow-Mechanismus nichts mitbekommen.
        if (!SessionManager().isDemo && nextcloud.usesLoginFlow)
          AsyncListTile(
            leading: const Icon(Icons.cloud_sync_outlined),
            title: const Text('Nextcloud neu verbinden'),
            subtitle: const Text('Bei Anmeldeproblemen in Talk oder Dateien'),
            closeOnSuccess: false,
            onPressed: _reconnectNextcloud,
          ),
      ],
    );
  }

  /// Erneuert die Nextcloud-Zugangsdaten über den Login Flow v2 (inkl. des
  /// zweiten Talk-Durchlaufs) und bindet die Push-Subscription neu.
  Future<void> _reconnectNextcloud() async {
    final ok = await AppRoutes.openNextcloudLoginFlow(context);
    if (!ok || !mounted) return;
    // Neues App-Passwort = neue NC-Session: die Push-Subscription neu binden.
    unawaited(PushRegistration().register());
    ScaffoldMessenger.of(context).showSnackBar(
      const SnackBar(content: Text('Nextcloud-Verbindung erneuert.')),
    );
  }
}

Future<void> _confirmLogout(BuildContext context) async {
  final accountBloc = context.read<AccountBloc>();
  final others = SessionManager().accounts.value.accounts.length - 1;
  String? nextAccountId;
  // Flip AccountBloc state only after the dialog fully closes: doing it from
  // inside the sign-out (the previous approach) raced AsyncDialogAction's
  // pop(true) against the navigator teardown of the account switch.
  final confirmed = await showDialog<bool>(
    context: context,
    builder: (dialogContext) => ConfirmDialog(
      title: 'Abmelden?',
      content: others > 0
          ? 'Möchtest du dich wirklich abmelden? Die App wechselt danach zu '
                'einem deiner anderen Konten.'
          : 'Möchtest du dich wirklich abmelden?',
      confirmButton: 'Abmelden',
      onConfirmAsync: () async =>
          nextAccountId = await SessionLifecycle.signOut(),
    ),
  );
  if (confirmed != true) return;
  accountBloc.activated(nextAccountId);
}

class _AccountName extends StatelessWidget {
  final String name;
  final String identity;

  const _AccountName({required this.name, required this.identity});

  @override
  Widget build(BuildContext context) => Column(
    crossAxisAlignment: CrossAxisAlignment.start,
    mainAxisSize: MainAxisSize.min,
    children: [
      Text(
        name,
        style: const TextStyle(fontSize: 20, fontWeight: FontWeight.w600),
        maxLines: 2,
        overflow: TextOverflow.ellipsis,
      ),
      const SizedBox(height: 2),
      Text(
        identity,
        style: TextStyle(
          fontSize: 13,
          color: Theme.of(context).colorScheme.onSurfaceVariant,
        ),
        maxLines: 1,
        overflow: TextOverflow.ellipsis,
      ),
    ],
  );
}

class _AccountActions extends StatelessWidget {
  const _AccountActions();

  @override
  Widget build(BuildContext context) => Column(
    mainAxisSize: MainAxisSize.min,
    crossAxisAlignment: CrossAxisAlignment.start,
    children: [
      TextButton.icon(
        style: compactAccountButtonStyle,
        icon: const Icon(Icons.logout_outlined, size: 18),
        label: const Text('Abmelden'),
        onPressed: () => _confirmLogout(context),
      ),
      const AccountSwitchButton(),
    ],
  );
}

class _AvatarEditBadge extends StatelessWidget {
  final bool busy;
  final VoidCallback? onTap;
  const _AvatarEditBadge({required this.busy, required this.onTap});

  @override
  Widget build(BuildContext context) {
    final theme = Theme.of(context);
    return Material(
      color: theme.colorScheme.primary,
      shape: const CircleBorder(),
      elevation: 2,
      child: InkWell(
        customBorder: const CircleBorder(),
        onTap: onTap,
        child: SizedBox(
          width: 27,
          height: 27,
          child: busy
              ? Padding(
                  padding: const EdgeInsets.all(6),
                  child: AppProgressIndicator.small(
                    color: theme.colorScheme.onPrimary,
                  ),
                )
              : Icon(Icons.edit, size: 14, color: theme.colorScheme.onPrimary),
        ),
      ),
    );
  }
}