/// Multi-select sheet for adding catalog products to a shopping list.
library;

import 'package:flutter/material.dart';

import '../models/product.dart';
import 'product_image.dart';

class AddListItemSelection {
  const AddListItemSelection({required this.name, this.productId});

  final String name;
  final int? productId;
}

Future<List<AddListItemSelection>?> showAddListItemsSheet(
  BuildContext context, {
  required List<Product> products,
}) {
  return showModalBottomSheet<List<AddListItemSelection>>(
    context: context,
    isScrollControlled: true,
    showDragHandle: true,
    builder: (context) => _AddListItemsSheet(products: products),
  );
}

class _AddListItemsSheet extends StatefulWidget {
  const _AddListItemsSheet({required this.products});

  final List<Product> products;

  @override
  State<_AddListItemsSheet> createState() => _AddListItemsSheetState();
}

class _AddListItemsSheetState extends State<_AddListItemsSheet> {
  final TextEditingController _controller = TextEditingController();
  final Set<int> _selectedProductIds = {};
  String? _error;

  @override
  void dispose() {
    _controller.dispose();
    super.dispose();
  }

  List<Product> get _matches {
    final query = _controller.text.trim().toLowerCase();
    if (query.isEmpty) return widget.products;
    return widget.products
        .where((product) => product.name.toLowerCase().contains(query))
        .toList();
  }

  int get _addCount {
    var count = _selectedProductIds.length;
    final typed = _controller.text.trim();
    if (typed.isEmpty) return count;
    final selectedNames = {
      for (final product in widget.products)
        if (_selectedProductIds.contains(product.id))
          product.name.toLowerCase(),
    };
    if (!selectedNames.contains(typed.toLowerCase())) count++;
    return count;
  }

  void _toggleProduct(Product product) {
    setState(() {
      if (_selectedProductIds.contains(product.id)) {
        _selectedProductIds.remove(product.id);
      } else {
        _selectedProductIds.add(product.id);
      }
      _error = null;
    });
  }

  void _add() {
    final selections = <AddListItemSelection>[
      for (final product in widget.products)
        if (_selectedProductIds.contains(product.id))
          AddListItemSelection(name: product.name, productId: product.id),
    ];
    final typed = _controller.text.trim();
    if (typed.isNotEmpty &&
        !selections.any(
          (item) => item.name.toLowerCase() == typed.toLowerCase(),
        )) {
      selections.add(AddListItemSelection(name: typed));
    }
    if (selections.isEmpty) {
      setState(() => _error = 'Select products or enter an item name.');
      return;
    }
    Navigator.of(context).pop(selections);
  }

  @override
  Widget build(BuildContext context) {
    final theme = Theme.of(context);
    final bottom = MediaQuery.viewInsetsOf(context).bottom;
    final matches = _matches;
    final addCount = _addCount;

    return Padding(
      padding: EdgeInsets.fromLTRB(16, 0, 16, 16 + bottom),
      child: SizedBox(
        height: MediaQuery.sizeOf(context).height * 0.72,
        child: Column(
          crossAxisAlignment: CrossAxisAlignment.stretch,
          children: [
            Text('Add items', style: theme.textTheme.titleLarge),
            const SizedBox(height: 12),
            TextField(
              controller: _controller,
              autofocus: true,
              textCapitalization: TextCapitalization.sentences,
              decoration: const InputDecoration(
                labelText: 'Search or type a new item',
              ),
              onChanged: (_) => setState(() => _error = null),
            ),
            if (_error != null) ...[
              const SizedBox(height: 8),
              Text(_error!, style: TextStyle(color: theme.colorScheme.error)),
            ],
            const SizedBox(height: 8),
            Text('From products', style: theme.textTheme.labelMedium),
            const SizedBox(height: 4),
            Expanded(
              child: matches.isEmpty
                  ? Center(
                      child: Text(
                        widget.products.isEmpty
                            ? 'No products in your catalog yet.'
                            : 'No products match this search.',
                        style: theme.textTheme.bodyMedium,
                      ),
                    )
                  : ListView.builder(
                      itemCount: matches.length,
                      itemBuilder: (context, index) {
                        final product = matches[index];
                        final selected = _selectedProductIds.contains(
                          product.id,
                        );
                        return ListTile(
                          contentPadding: EdgeInsets.zero,
                          leading: Checkbox(
                            value: selected,
                            onChanged: (_) => _toggleProduct(product),
                          ),
                          title: Text(product.name),
                          trailing: ProductImage(
                            name: product.name,
                            path: product.imagePath,
                            size: 32,
                          ),
                          onTap: () => _toggleProduct(product),
                        );
                      },
                    ),
            ),
            FilledButton(
              onPressed: addCount == 0 ? null : _add,
              child: Text(addCount == 1 ? 'Add 1 item' : 'Add $addCount items'),
            ),
          ],
        ),
      ),
    );
  }
}