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

import '../../../api/marianumconnect/queries/get_capabilities/guardian_child.dart';
import '../../../push/notification_permission_prompt.dart';
import '../../../routing/app_routes.dart';
import '../../../state/app/infrastructure/loadable_state/view/loadable_state_consumer.dart';
import '../../../state/app/modules/capabilities/bloc/capabilities_cubit.dart';
import '../../../state/app/modules/parent_letters/bloc/parent_letters_bloc.dart';
import '../../../state/app/modules/parent_letters/bloc/parent_letters_state.dart';
import '../../../state/app/modules/parent_letters/parent_letters_logic.dart';
import '../../../widget/async_action_button.dart';
import '../../../widget/child_switcher.dart';
import '../../../widget/placeholder_view.dart';
import 'widgets/parent_letter_tile.dart';

class ParentLettersView extends StatefulWidget {
  const ParentLettersView({super.key});

  @override
  State<ParentLettersView> createState() => _ParentLettersViewState();
}

class _ParentLettersViewState extends State<ParentLettersView> {
  /// Null shows the letters of all children. Deliberately independent of the
  /// app-wide child selection: the inbox must not hide a sibling's letters.
  String? _childFilter;

  @override
  void initState() {
    super.initState();
    WidgetsBinding.instance.addPostFrameCallback((_) {
      if (!mounted) return;
      context.read<ParentLettersBloc>().refresh(silent: true);
      maybePromptParentLetterNotifications(context);
    });
  }

  @override
  Widget build(BuildContext context) {
    final children = context.watch<CapabilitiesCubit>().state.children;
    final filter = children.any((child) => child.id == _childFilter)
        ? _childFilter
        : null;
    return Scaffold(
      appBar: AppBar(title: const Text('Elternbriefe')),
      body: Column(
        children: [
          if (children.length > 1)
            _ChildFilterBar(
              children: children,
              selected: filter,
              onSelected: (id) => setState(() => _childFilter = id),
            ),
          Expanded(
            child: LoadableStateConsumer<ParentLettersBloc, ParentLettersState>(
              child: (state, loading) {
                if (children.isEmpty) return const NoChildrenPlaceholder();
                final letters = filterLettersByChild(state.letters, filter);
                if (letters.isEmpty && !state.hasMore) {
                  return const PlaceholderView(
                    icon: Icons.mark_email_read_outlined,
                    text: 'Keine Elternbriefe vorhanden.',
                  );
                }
                return ListView.separated(
                  physics: const AlwaysScrollableScrollPhysics(),
                  itemCount: letters.length + (state.hasMore ? 1 : 0),
                  separatorBuilder: (_, _) => const Divider(height: 1),
                  itemBuilder: (context, index) {
                    if (index == letters.length) {
                      return Padding(
                        padding: const EdgeInsets.all(8),
                        child: AsyncTextButton(
                          onPressed: context
                              .read<ParentLettersBloc>()
                              .loadOlder,
                          child: const Text('Ältere Elternbriefe laden'),
                        ),
                      );
                    }
                    final letter = letters[index];
                    return ParentLetterTile(
                      letter: letter,
                      children: children,
                      onTap: () =>
                          AppRoutes.openParentLetter(context, id: letter.id),
                    );
                  },
                );
              },
            ),
          ),
        ],
      ),
    );
  }
}

class _ChildFilterBar extends StatelessWidget {
  final List<GuardianChild> children;
  final String? selected;
  final ValueChanged<String?> onSelected;

  const _ChildFilterBar({
    required this.children,
    required this.selected,
    required this.onSelected,
  });

  @override
  Widget build(BuildContext context) => SingleChildScrollView(
    scrollDirection: Axis.horizontal,
    padding: const EdgeInsets.symmetric(horizontal: 12, vertical: 4),
    child: Row(
      spacing: 8,
      children: [
        ChoiceChip(
          label: const Text('Alle'),
          selected: selected == null,
          onSelected: (_) => onSelected(null),
        ),
        for (final child in children)
          ChoiceChip(
            label: Text(child.firstName),
            selected: selected == child.id,
            onSelected: (_) => onSelected(child.id),
          ),
      ],
    ),
  );
}