/// Named shopping lists of things to buy.
library;

import 'package:flutter/material.dart';

import 'models/shopping_list.dart';
import 'services/product_repository.dart';
import 'shopping_list_detail_screen.dart';
import 'utils/dates.dart';
import 'widgets/confirm_dialog.dart';
import 'widgets/name_dialog.dart';
import 'widgets/profile_button.dart';
import 'widgets/settings_button.dart';

class ShoppingListsScreen extends StatefulWidget {
  const ShoppingListsScreen({super.key, required this.repository});

  final ProductRepository repository;

  @override
  State<ShoppingListsScreen> createState() => _ShoppingListsScreenState();
}

class _ShoppingListsScreenState extends State<ShoppingListsScreen> {
  List<ShoppingList>? _lists;
  Object? _error;
  bool _editing = false;
  int _loadToken = 0;

  bool get _hasLists => _lists != null && _lists!.isNotEmpty;

  @override
  void initState() {
    super.initState();
    widget.repository.addListener(_load);
    _load();
  }

  @override
  void dispose() {
    widget.repository.removeListener(_load);
    super.dispose();
  }

  Future<void> _load() async {
    final token = ++_loadToken;
    try {
      final lists = await widget.repository.getShoppingLists();
      if (!mounted || token != _loadToken) return;
      setState(() {
        _lists = lists;
        _error = null;
        if (lists.isEmpty) _editing = false;
      });
    } catch (error) {
      if (!mounted || token != _loadToken) return;
      setState(() => _error = error);
    }
  }

  Future<void> _create() async {
    final name = await showNameDialog(
      context,
      title: 'New shopping list',
      label: 'List name',
      confirmLabel: 'Create',
    );
    if (name == null || !mounted) return;
    final id = await widget.repository.createShoppingList(name);
    if (!mounted) return;
    await _openList(id);
  }

  Future<void> _openList(int id) async {
    await Navigator.of(context).push<void>(
      MaterialPageRoute(
        builder: (_) =>
            ShoppingListDetailScreen(repository: widget.repository, listId: id),
      ),
    );
    if (mounted) _load();
  }

  Future<void> _removeList(ShoppingList list) async {
    final confirmed = await confirmAction(
      context,
      title: 'Delete shopping list?',
      message: '"${list.name}" and its items will be deleted.',
    );
    if (!confirmed || !mounted) return;
    setState(() {
      _lists = [
        for (final item in _lists ?? const <ShoppingList>[])
          if (item.id != list.id) item,
      ];
      if (_lists!.isEmpty) _editing = false;
    });
    try {
      await widget.repository.deleteShoppingList(list.id);
    } catch (_) {
      if (mounted) _load();
    }
  }

  @override
  Widget build(BuildContext context) {
    final theme = Theme.of(context);

    return Scaffold(
      appBar: AppBar(
        title: const Text('Shopping lists'),
        actions: [
          if (_hasLists)
            IconButton(
              tooltip: _editing ? 'Done' : 'Edit',
              onPressed: () => setState(() => _editing = !_editing),
              icon: Icon(_editing ? Icons.check : Icons.edit_outlined),
            ),
          const ProfileButton(),
          const SettingsButton(),
        ],
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: _create,
        tooltip: 'New list',
        child: const Icon(Icons.add),
      ),
      body: _error != null && _lists == null
          ? Center(
              child: Text(
                'Could not load shopping lists.',
                style: theme.textTheme.bodyLarge,
              ),
            )
          : _lists == null
          ? const Center(child: CircularProgressIndicator())
          : _lists!.isEmpty
          ? Center(
              child: Text(
                'Create a list for your next shop.',
                textAlign: TextAlign.center,
                style: theme.textTheme.bodyLarge,
              ),
            )
          : ListView.separated(
              padding: const EdgeInsets.fromLTRB(8, 8, 8, 88),
              itemCount: _lists!.length,
              separatorBuilder: (_, _) => const SizedBox(height: 4),
              itemBuilder: (context, index) {
                final list = _lists![index];
                final remaining = list.itemCount - list.checkedCount;
                return ListTile(
                  leading: CircleAvatar(child: Text('${list.itemCount}')),
                  title: Text('${list.name} (${formatDate(list.createdAt)})'),
                  subtitle: Text(
                    list.itemCount == 0
                        ? 'Empty'
                        : remaining == 0
                        ? 'All done'
                        : remaining == 1
                        ? '1 item left'
                        : '$remaining items left',
                  ),
                  trailing: _editing
                      ? IconButton(
                          tooltip: 'Delete',
                          onPressed: () => _removeList(list),
                          icon: const Icon(Icons.delete_outline),
                        )
                      : const Icon(Icons.chevron_right),
                  onTap: _editing ? null : () => _openList(list.id),
                );
              },
            ),
    );
  }
}