tasq/lib/screens/searchable_multi_select_dropdown.dart

import 'package:flutter/material.dart';

/// Searchable multi-select dropdown with chips and 'Select All' option
class SearchableMultiSelectDropdown<T> extends StatefulWidget {
  const SearchableMultiSelectDropdown({
    Key? key,
    required this.label,
    required this.items,
    required this.selectedIds,
    required this.getId,
    required this.getLabel,
    required this.onChanged,
  }) : super(key: key);

  final String label;
  final List<T> items;
  final List<String> selectedIds;
  final String Function(T) getId;
  final String Function(T) getLabel;
  final ValueChanged<List<String>> onChanged;

  @override
  State<SearchableMultiSelectDropdown<T>> createState() =>
      SearchableMultiSelectDropdownState<T>();
}

class SearchableMultiSelectDropdownState<T>
    extends State<SearchableMultiSelectDropdown<T>> {
  late List<String> _selectedIds;
  String _search = '';
  bool _selectAll = false;

  @override
  void initState() {
    super.initState();
    _selectedIds = List<String>.from(widget.selectedIds);
    _selectAll =
        _selectedIds.length == widget.items.length && widget.items.isNotEmpty;
  }

  void _openDropdown() async {
    await showDialog(
      context: context,
      builder: (context) {
        return StatefulBuilder(
          builder: (context, setState) {
            final filtered = widget.items
                .where(
                  (item) => widget
                      .getLabel(item)
                      .toLowerCase()
                      .contains(_search.toLowerCase()),
                )
                .toList();
            return AlertDialog(
              title: Text('Select ${widget.label}'),
              content: Column(
                mainAxisSize: MainAxisSize.min,
                children: [
                  TextField(
                    decoration: const InputDecoration(hintText: 'Search...'),
                    onChanged: (v) => setState(() => _search = v),
                  ),
                  CheckboxListTile(
                    value: _selectAll,
                    title: const Text('Select All'),
                    onChanged: (checked) {
                      setState(() {
                        _selectAll = checked ?? false;
                        if (_selectAll) {
                          _selectedIds = widget.items
                              .map(widget.getId)
                              .toList();
                        } else {
                          _selectedIds.clear();
                        }
                      });
                    },
                  ),
                  SizedBox(
                    height: 200,
                    child: ListView(
                      children: [
                        for (final item in filtered)
                          CheckboxListTile(
                            value: _selectedIds.contains(widget.getId(item)),
                            title: Text(widget.getLabel(item)),
                            onChanged: (checked) {
                              setState(() {
                                final id = widget.getId(item);
                                if (checked == true) {
                                  _selectedIds.add(id);
                                } else {
                                  _selectedIds.remove(id);
                                }
                                _selectAll =
                                    _selectedIds.length ==
                                        widget.items.length &&
                                    widget.items.isNotEmpty;
                              });
                            },
                          ),
                      ],
                    ),
                  ),
                ],
              ),
              actions: [
                TextButton(
                  onPressed: () => Navigator.of(context).pop(),
                  child: const Text('Cancel'),
                ),
                ElevatedButton(
                  onPressed: () => Navigator.of(context).pop(_selectedIds),
                  child: const Text('Done'),
                ),
              ],
            );
          },
        );
      },
    ).then((result) {
      if (result is List<String>) {
        setState(() {
          _selectedIds = result;
          _selectAll =
              _selectedIds.length == widget.items.length &&
              widget.items.isNotEmpty;
        });
        widget.onChanged(_selectedIds);
      }
    });
  }

  @override
  Widget build(BuildContext context) {
    return Column(
      crossAxisAlignment: CrossAxisAlignment.start,
      children: [
        InputDecorator(
          decoration: InputDecoration(labelText: widget.label),
          child: Wrap(
            spacing: 8,
            runSpacing: 4,
            children: [
              ..._selectedIds.map((id) {
                T item;
                try {
                  item = widget.items.firstWhere((e) => widget.getId(e) == id);
                } catch (_) {
                  return const SizedBox.shrink();
                }
                return Chip(
                  label: Text(widget.getLabel(item)),
                  onDeleted: () {
                    setState(() {
                      _selectedIds.remove(id);
                      _selectAll =
                          _selectedIds.length == widget.items.length &&
                          widget.items.isNotEmpty;
                    });
                    widget.onChanged(_selectedIds);
                  },
                );
              }),
              ActionChip(
                label: Text('Select'),
                avatar: const Icon(Icons.arrow_drop_down),
                onPressed: _openDropdown,
              ),
            ],
          ),
        ),
      ],
    );
  }
}