// Copyright 2014 The Flutter Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

import 'package:flutter/material.dart';

/// Flutter code sample for [ExpansionPanelList].

void main() => runApp(const ExpansionPanelListExampleApp());

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

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(title: const Text('ExpansionPanelList Sample')),
        body: const ExpansionPanelListExample(),
      ),
    );
  }
}

// stores ExpansionPanel state information
class Item {
  Item({
    required this.expandedValue,
    required this.headerValue,
    this.isExpanded = false,
  });

  String expandedValue;
  String headerValue;
  bool isExpanded;
}

List<Item> generateItems(int numberOfItems) {
  return List<Item>.generate(numberOfItems, (int index) {
    return Item(
      headerValue: 'Panel $index',
      expandedValue: 'This is item number $index',
    );
  });
}

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

  @override
  State<ExpansionPanelListExample> createState() =>
      _ExpansionPanelListExampleState();
}

class _ExpansionPanelListExampleState extends State<ExpansionPanelListExample> {
  final List<Item> _data = generateItems(8);

  @override
  Widget build(BuildContext context) {
    return SingleChildScrollView(child: Container(child: _buildPanel()));
  }

  Widget _buildPanel() {
    return ExpansionPanelList(
      expansionCallback: (int index, bool isExpanded) {
        setState(() {
          _data[index].isExpanded = isExpanded;
        });
      },
      children: _data.map<ExpansionPanel>((Item item) {
        return ExpansionPanel(
          headerBuilder: (BuildContext context, bool isExpanded) {
            return ListTile(title: Text(item.headerValue));
          },
          body: ListTile(
            title: Text(item.expandedValue),
            subtitle: const Text(
              'To delete this panel, tap the trash can icon',
            ),
            trailing: const Icon(Icons.delete),
            onTap: () {
              setState(() {
                _data.removeWhere((Item currentItem) => item == currentItem);
              });
            },
          ),
          isExpanded: item.isExpanded,
        );
      }).toList(),
    );
  }
}