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

import '../../../models/sys_menu.dart';
import '../../../services/api_client.dart';
import '../../../services/sys_service.dart';

/// 菜单管理页（树形展示）。
class MenuPage extends ConsumerStatefulWidget {
  const MenuPage({super.key});

  @override
  ConsumerState<MenuPage> createState() => _MenuPageState();
}

class _MenuPageState extends ConsumerState<MenuPage> {
  final SystemService _service = SystemService();

  List<SysMenu> _items = [];
  bool _loading = false;
  String? _error;

  @override
  void initState() {
    super.initState();
    _loadData();
  }

  Future<void> _loadData() async {
    setState(() {
      _loading = true;
      _error = null;
    });
    try {
      _items = await _service.getMenuList();
    } on ApiException catch (e) {
      _error = e.message;
    } catch (e) {
      _error = e.toString();
    } finally {
      if (mounted) setState(() => _loading = false);
    }
  }

  Future<void> _refresh() async {
    await _loadData();
  }

  /// 构建菜单树：parentId 为空或 "0" 的为根节点。
  List<_MenuNode> _buildTree(List<SysMenu> menus) {
    final nodeMap = <String, _MenuNode>{};
    for (final menu in menus) {
      nodeMap[menu.menuId] = _MenuNode(menu: menu);
    }

    final roots = <_MenuNode>[];
    for (final menu in menus) {
      final node = nodeMap[menu.menuId]!;
      final parentId = menu.parentId.isEmpty || menu.parentId == '0'
          ? null
          : menu.parentId;
      if (parentId == null || !nodeMap.containsKey(parentId)) {
        roots.add(node);
      } else {
        nodeMap[parentId]!.children.add(node);
      }
    }

    // 排序
    void sortNodes(List<_MenuNode> nodes) {
      nodes.sort((a, b) => a.menu.orderNum.compareTo(b.menu.orderNum));
      for (final node in nodes) {
        sortNodes(node.children);
      }
    }

    sortNodes(roots);
    return roots;
  }

  Future<void> _showForm({SysMenu? menu}) async {
    final result = await showModalBottomSheet<Map<String, dynamic>>(
      context: context,
      isScrollControlled: true,
      builder: (context) => _MenuForm(menu: menu, allMenus: _items),
    );

    if (result == null) return;

    try {
      await _service.saveMenu(result);
      if (mounted) {
        ScaffoldMessenger.of(context).showSnackBar(
          const SnackBar(content: Text('保存成功')),
        );
        _refresh();
      }
    } on ApiException catch (e) {
      if (mounted) {
        ScaffoldMessenger.of(context).showSnackBar(
          SnackBar(content: Text(e.message)),
        );
      }
    } catch (e) {
      if (mounted) {
        ScaffoldMessenger.of(context).showSnackBar(
          SnackBar(content: Text('保存失败：$e')),
        );
      }
    }
  }

  Future<void> _deleteMenu(SysMenu menu) async {
    final confirmed = await showDialog<bool>(
      context: context,
      builder: (context) => AlertDialog(
        title: const Text('确认删除'),
        content: Text('确定要删除菜单「${menu.name}」吗？'),
        actions: [
          TextButton(
            onPressed: () => Navigator.pop(context, false),
            child: const Text('取消'),
          ),
          FilledButton(
            onPressed: () => Navigator.pop(context, true),
            child: const Text('删除'),
          ),
        ],
      ),
    );

    if (confirmed != true) return;

    try {
      await _service.deleteMenu(menu.menuId);
      if (mounted) {
        ScaffoldMessenger.of(context).showSnackBar(
          const SnackBar(content: Text('删除成功')),
        );
        _refresh();
      }
    } on ApiException catch (e) {
      if (mounted) {
        ScaffoldMessenger.of(context).showSnackBar(
          SnackBar(content: Text(e.message)),
        );
      }
    } catch (e) {
      if (mounted) {
        ScaffoldMessenger.of(context).showSnackBar(
          SnackBar(content: Text('删除失败：$e')),
        );
      }
    }
  }

  String _typeLabel(int type) {
    switch (type) {
      case 0:
        return '目录';
      case 1:
        return '菜单';
      case 2:
        return '按钮';
      default:
        return '未知';
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(automaticallyImplyLeading: false, title: const Text('菜单管理')),
      body: _buildBody(),
      floatingActionButton: FloatingActionButton(
        onPressed: () => _showForm(),
        child: const Icon(Icons.add),
      ),
    );
  }

  Widget _buildBody() {
    if (_loading) {
      return const Center(child: CircularProgressIndicator());
    }

    if (_error != null) {
      return Center(
        child: Column(
          mainAxisSize: MainAxisSize.min,
          children: [
            Text(_error!),
            const SizedBox(height: 8),
            FilledButton.tonal(
              onPressed: _refresh,
              child: const Text('重试'),
            ),
          ],
        ),
      );
    }

    if (_items.isEmpty) {
      return const Center(child: Text('暂无数据'));
    }

    final tree = _buildTree(_items);

    return RefreshIndicator(
      onRefresh: _refresh,
      child: ListView.builder(
        physics: const AlwaysScrollableScrollPhysics(),
        itemCount: tree.length,
        itemBuilder: (context, index) {
          return _buildTreeNode(tree[index]);
        },
      ),
    );
  }

  Widget _buildTreeNode(_MenuNode node) {
    final menu = node.menu;
    final hasChildren = node.children.isNotEmpty;

    if (hasChildren) {
      return Card(
        margin: const EdgeInsets.symmetric(horizontal: 12, vertical: 4),
        child: ExpansionTile(
          leading: Icon(_iconData(menu.icon)),
          title: Text(menu.name),
          subtitle: Text(
            '${_typeLabel(menu.type)}  |  ${menu.url.isEmpty ? "无路由" : menu.url}',
          ),
          trailing: PopupMenuButton<String>(
            onSelected: (value) {
              if (value == 'edit') {
                _showForm(menu: menu);
              } else if (value == 'delete') {
                _deleteMenu(menu);
              }
            },
            itemBuilder: (context) => [
              const PopupMenuItem(value: 'edit', child: Text('编辑')),
              const PopupMenuItem(value: 'delete', child: Text('删除')),
            ],
          ),
          children: node.children.map((child) => _buildTreeNode(child)).toList(),
        ),
      );
    }

    return Card(
      margin: const EdgeInsets.symmetric(horizontal: 12, vertical: 4),
      child: ListTile(
        leading: Icon(_iconData(menu.icon)),
        title: Text(menu.name),
        subtitle: Text(
          '${_typeLabel(menu.type)}  |  ${menu.url.isEmpty ? "无路由" : menu.url}',
        ),
        trailing: PopupMenuButton<String>(
          onSelected: (value) {
            if (value == 'edit') {
              _showForm(menu: menu);
            } else if (value == 'delete') {
              _deleteMenu(menu);
            }
          },
          itemBuilder: (context) => [
            const PopupMenuItem(value: 'edit', child: Text('编辑')),
            const PopupMenuItem(value: 'delete', child: Text('删除')),
          ],
        ),
      ),
    );
  }

  IconData _iconData(String icon) {
    switch (icon) {
      case 'home':
        return Icons.home;
      case 'settings':
        return Icons.settings;
      case 'person':
        return Icons.person;
      case 'people':
        return Icons.people;
      case 'menu':
        return Icons.menu;
      case 'list':
        return Icons.list;
      case 'dashboard':
        return Icons.dashboard;
      case 'devices':
        return Icons.devices;
      case 'notifications':
        return Icons.notifications;
      default:
        return Icons.folder;
    }
  }
}

/// 菜单树节点辅助类。
class _MenuNode {
  _MenuNode({required this.menu});

  final SysMenu menu;
  final List<_MenuNode> children = [];
}

/// 菜单表单。
class _MenuForm extends StatefulWidget {
  const _MenuForm({this.menu, this.allMenus = const []});

  final SysMenu? menu;
  final List<SysMenu> allMenus;

  @override
  State<_MenuForm> createState() => _MenuFormState();
}

class _MenuFormState extends State<_MenuForm> {
  final _formKey = GlobalKey<FormState>();
  late TextEditingController _nameCtrl;
  late TextEditingController _urlCtrl;
  late TextEditingController _iconCtrl;
  late TextEditingController _orderNumCtrl;
  late TextEditingController _permsCtrl;
  late String _parentId;
  late int _type;
  late bool _show;

  @override
  void initState() {
    super.initState();
    final m = widget.menu;
    _nameCtrl = TextEditingController(text: m?.name ?? '');
    _urlCtrl = TextEditingController(text: m?.url ?? '');
    _iconCtrl = TextEditingController(text: m?.icon ?? '');
    _orderNumCtrl = TextEditingController(text: (m?.orderNum ?? 0).toString());
    _permsCtrl = TextEditingController(text: m?.perms ?? '');
    _parentId = m?.parentId ?? '0';
    _type = m?.type ?? 0;
    _show = (m?.show ?? 0) == 0;
  }

  @override
  void dispose() {
    _nameCtrl.dispose();
    _urlCtrl.dispose();
    _iconCtrl.dispose();
    _orderNumCtrl.dispose();
    _permsCtrl.dispose();
    super.dispose();
  }

  void _submit() {
    if (!_formKey.currentState!.validate()) return;
    final data = <String, dynamic>{
      'name': _nameCtrl.text.trim(),
      'parentId': _parentId,
      'type': _type,
      'url': _urlCtrl.text.trim(),
      'icon': _iconCtrl.text.trim(),
      'orderNum': int.tryParse(_orderNumCtrl.text.trim()) ?? 0,
      'perms': _permsCtrl.text.trim(),
      'show': _show ? 0 : 1,
    };
    if (widget.menu != null) {
      data['menuId'] = widget.menu!.menuId;
    }
    Navigator.pop(context, data);
  }

  @override
  Widget build(BuildContext context) {
    final isEdit = widget.menu != null;
    return Padding(
      padding: EdgeInsets.only(
        bottom: MediaQuery.of(context).viewInsets.bottom,
      ),
      child: SingleChildScrollView(
        padding: const EdgeInsets.all(16),
        child: Form(
          key: _formKey,
          child: Column(
            mainAxisSize: MainAxisSize.min,
            children: [
              Text(
                isEdit ? '编辑菜单' : '新增菜单',
                style: Theme.of(context).textTheme.titleLarge,
              ),
              const SizedBox(height: 16),
              TextFormField(
                controller: _nameCtrl,
                decoration: const InputDecoration(
                  labelText: '菜单名称',
                  border: OutlineInputBorder(),
                ),
                validator: (v) =>
                    (v == null || v.trim().isEmpty) ? '请输入菜单名称' : null,
              ),
              const SizedBox(height: 12),
              DropdownButtonFormField<String>(
                value: _parentId,
                decoration: const InputDecoration(
                  labelText: '父级菜单',
                  border: OutlineInputBorder(),
                ),
                items: [
                  const DropdownMenuItem(value: '0', child: Text('一级菜单')),
                  ...widget.allMenus.map((m) => DropdownMenuItem(
                        value: m.menuId,
                        child: Text(m.name),
                      )),
                ],
                onChanged: (v) => setState(() => _parentId = v ?? '0'),
              ),
              const SizedBox(height: 12),
              Row(
                children: [
                  Expanded(
                    child: RadioListTile<int>(
                      title: const Text('目录'),
                      value: 0,
                      groupValue: _type,
                      onChanged: (v) => setState(() => _type = v ?? 0),
                      contentPadding: EdgeInsets.zero,
                    ),
                  ),
                  Expanded(
                    child: RadioListTile<int>(
                      title: const Text('菜单'),
                      value: 1,
                      groupValue: _type,
                      onChanged: (v) => setState(() => _type = v ?? 1),
                      contentPadding: EdgeInsets.zero,
                    ),
                  ),
                  Expanded(
                    child: RadioListTile<int>(
                      title: const Text('按钮'),
                      value: 2,
                      groupValue: _type,
                      onChanged: (v) => setState(() => _type = v ?? 2),
                      contentPadding: EdgeInsets.zero,
                    ),
                  ),
                ],
              ),
              const SizedBox(height: 12),
              TextFormField(
                controller: _urlCtrl,
                decoration: const InputDecoration(
                  labelText: '路由地址',
                  border: OutlineInputBorder(),
                ),
              ),
              const SizedBox(height: 12),
              TextFormField(
                controller: _iconCtrl,
                decoration: const InputDecoration(
                  labelText: '图标',
                  border: OutlineInputBorder(),
                ),
              ),
              const SizedBox(height: 12),
              TextFormField(
                controller: _orderNumCtrl,
                keyboardType: TextInputType.number,
                decoration: const InputDecoration(
                  labelText: '排序号',
                  border: OutlineInputBorder(),
                ),
              ),
              const SizedBox(height: 12),
              TextFormField(
                controller: _permsCtrl,
                decoration: const InputDecoration(
                  labelText: '权限标识',
                  border: OutlineInputBorder(),
                ),
              ),
              const SizedBox(height: 12),
              SwitchListTile(
                title: const Text('是否显示'),
                value: _show,
                onChanged: (v) => setState(() => _show = v),
              ),
              const SizedBox(height: 24),
              Row(
                mainAxisAlignment: MainAxisAlignment.end,
                children: [
                  TextButton(
                    onPressed: () => Navigator.pop(context),
                    child: const Text('取消'),
                  ),
                  const SizedBox(width: 8),
                  FilledButton(
                    onPressed: _submit,
                    child: const Text('保存'),
                  ),
                ],
              ),
            ],
          ),
        ),
      ),
    );
  }
}