import 'package:flutter/material.dart';
import 'package:provider/provider.dart';
import '../models/category_model.dart';
import '../providers/expense_provider.dart';

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

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('分类管理'),
      ),
      body: Consumer<ExpenseProvider>(
        builder: (context, provider, child) {
          final rootCategories = provider.rootCategories;
          return ListView.builder(
            itemCount: rootCategories.length,
            itemBuilder: (context, index) {
              return _buildCategoryTile(context, rootCategories[index], provider);
            },
          );
        },
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: () => _showAddEditDialog(context, null, null),
        child: const Icon(Icons.add),
      ),
    );
  }

  Widget _buildCategoryTile(BuildContext context, Category category, ExpenseProvider provider) {
    final subCategories = provider.getSubCategories(category.id!);
    
    if (subCategories.isEmpty) {
      return ListTile(
        leading: CircleAvatar(
          backgroundColor: Color(category.color),
          child: Icon(_getIconData(category.icon), color: Colors.white, size: 20),
        ),
        title: Text(category.name),
        trailing: _buildActionButtons(context, category),
      );
    }

    return ExpansionTile(
      leading: CircleAvatar(
        backgroundColor: Color(category.color),
        child: Icon(_getIconData(category.icon), color: Colors.white, size: 20),
      ),
      title: Text(category.name),
      trailing: Row(
        mainAxisSize: MainAxisSize.min,
        children: [
           // This trailing overrides the expansion arrow, so maybe we put actions in leading or long press?
           // ExpansionTile doesn't easily support custom trailing + expansion arrow. 
           // Let's use PopupMenuButton for actions instead.
           _buildActionButtons(context, category),
           const Icon(Icons.expand_more), // Visual cue, though functionality is tricky if trailing is used
        ],
      ),
      children: subCategories.map((sub) => _buildCategoryTile(context, sub, provider)).toList(),
    );
  }

  // Adjusted to use PopupMenu for cleaner UI on tiles
  Widget _buildActionButtons(BuildContext context, Category category) {
    return PopupMenuButton<String>(
      onSelected: (value) {
        if (value == 'edit') {
          _showAddEditDialog(context, category, category.parentId);
        } else if (value == 'delete') {
          _confirmDelete(context, category);
        } else if (value == 'add_sub') {
          _showAddEditDialog(context, null, category.id);
        }
      },
      itemBuilder: (BuildContext context) => <PopupMenuEntry<String>>[
        const PopupMenuItem<String>(
          value: 'edit',
          child: Text('编辑'),
        ),
        const PopupMenuItem<String>(
          value: 'add_sub',
          child: Text('添加子分类'),
        ),
        const PopupMenuItem<String>(
          value: 'delete',
          child: Text('删除', style: TextStyle(color: Colors.red)),
        ),
      ],
    );
  }

  void _confirmDelete(BuildContext context, Category category) {
    showDialog(
      context: context,
      builder: (ctx) => AlertDialog(
        title: const Text('确认删除'),
        content: Text('确定要删除分类 "${category.name}" 吗？'),
        actions: [
          TextButton(
            onPressed: () => Navigator.of(ctx).pop(),
            child: const Text('取消'),
          ),
          TextButton(
            onPressed: () {
              Provider.of<ExpenseProvider>(context, listen: false).deleteCategory(category.id!);
              Navigator.of(ctx).pop();
            },
            child: const Text('删除', style: TextStyle(color: Colors.red)),
          ),
        ],
      ),
    );
  }

  void _showAddEditDialog(BuildContext context, Category? category, int? parentId) {
    final isEditing = category != null;
    final nameController = TextEditingController(text: isEditing ? category.name : '');
    String selectedType = isEditing ? category.type : 'expense';
    String selectedIcon = isEditing ? category.icon : 'category';
    int selectedColor = isEditing ? category.color : 0xFF2196F3;

    showDialog(
      context: context,
      builder: (ctx) {
        return StatefulBuilder(
          builder: (context, setState) {
            return AlertDialog(
              title: Text(isEditing ? '编辑分类' : '添加分类'),
              content: SingleChildScrollView(
                child: Column(
                  mainAxisSize: MainAxisSize.min,
                  children: [
                    TextField(
                      controller: nameController,
                      decoration: const InputDecoration(labelText: '分类名称'),
                    ),
                    const SizedBox(height: 16),
                    DropdownButtonFormField<String>(
                      key: ValueKey(selectedType),
                      initialValue: selectedType,
                      items: const [
                        DropdownMenuItem(value: 'expense', child: Text('支出')),
                        DropdownMenuItem(value: 'income', child: Text('收入')),
                      ],
                      onChanged: (val) {
                        setState(() => selectedType = val!);
                      },
                      decoration: const InputDecoration(labelText: '类型'),
                    ),
                    const SizedBox(height: 16),
                    // Icon Picker (Simple version)
                    DropdownButtonFormField<String>(
                      key: ValueKey(selectedIcon),
                      initialValue: selectedIcon,
                      items: const [
                        DropdownMenuItem(value: 'restaurant', child: Icon(Icons.restaurant)),
                        DropdownMenuItem(value: 'directions_bus', child: Icon(Icons.directions_bus)),
                        DropdownMenuItem(value: 'shopping_cart', child: Icon(Icons.shopping_cart)),
                        DropdownMenuItem(value: 'movie', child: Icon(Icons.movie)),
                        DropdownMenuItem(value: 'local_hospital', child: Icon(Icons.local_hospital)),
                        DropdownMenuItem(value: 'attach_money', child: Icon(Icons.attach_money)),
                        DropdownMenuItem(value: 'trending_up', child: Icon(Icons.trending_up)),
                        DropdownMenuItem(value: 'category', child: Icon(Icons.category)),
                        DropdownMenuItem(value: 'breakfast_dining', child: Icon(Icons.breakfast_dining)),
                        DropdownMenuItem(value: 'lunch_dining', child: Icon(Icons.lunch_dining)),
                        DropdownMenuItem(value: 'dinner_dining', child: Icon(Icons.dinner_dining)),
                        DropdownMenuItem(value: 'subway', child: Icon(Icons.subway)),
                        DropdownMenuItem(value: 'local_taxi', child: Icon(Icons.local_taxi)),
                      ],
                      onChanged: (val) {
                         setState(() => selectedIcon = val!);
                      },
                      decoration: const InputDecoration(labelText: '图标'),
                    ),
                  ],
                ),
              ),
              actions: [
                TextButton(
                  onPressed: () => Navigator.of(ctx).pop(),
                  child: const Text('取消'),
                ),
                ElevatedButton(
                  onPressed: () {
                    if (nameController.text.isEmpty) return;
                    
                    final newCategory = Category(
                      id: category?.id,
                      name: nameController.text,
                      type: selectedType,
                      icon: selectedIcon,
                      color: selectedColor, // Fixed color for now or add picker
                      parentId: parentId,
                    );

                    if (isEditing) {
                      Provider.of<ExpenseProvider>(context, listen: false).updateCategory(newCategory);
                    } else {
                      Provider.of<ExpenseProvider>(context, listen: false).addCategory(newCategory);
                    }
                    Navigator.of(ctx).pop();
                  },
                  child: const Text('保存'),
                ),
              ],
            );
          },
        );
      },
    );
  }

  IconData _getIconData(String iconName) {
    switch (iconName) {
      case 'restaurant': return Icons.restaurant;
      case 'directions_bus': return Icons.directions_bus;
      case 'shopping_cart': return Icons.shopping_cart;
      case 'movie': return Icons.movie;
      case 'local_hospital': return Icons.local_hospital;
      case 'attach_money': return Icons.attach_money;
      case 'trending_up': return Icons.trending_up;
      case 'breakfast_dining': return Icons.breakfast_dining;
      case 'lunch_dining': return Icons.lunch_dining;
      case 'dinner_dining': return Icons.dinner_dining;
      case 'subway': return Icons.subway;
      case 'local_taxi': return Icons.local_taxi;
      default: return Icons.category;
    }
  }
}