import 'package:flutter/material.dart';
import 'package:provider/provider.dart';
import 'package:intl/intl.dart';
import 'package:uuid/uuid.dart';
import '../models/transaction_model.dart';
import '../providers/expense_provider.dart';

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

  @override
  State<AddTransactionScreen> createState() => _AddTransactionScreenState();
}

class _AddTransactionScreenState extends State<AddTransactionScreen> {
  final _formKey = GlobalKey<FormState>();
  final _amountController = TextEditingController();
  final _noteController = TextEditingController();
  DateTime _selectedDate = DateTime.now();
  String _transactionType = 'expense';
  int? _selectedCategoryId;

  @override
  Widget build(BuildContext context) {
    final provider = Provider.of<ExpenseProvider>(context);
    
    // Flatten categories with hierarchy logic for display
    final List<DropdownMenuItem<int>> categoryItems = [];
    final rootCategories = provider.rootCategories.where((c) => c.type == _transactionType).toList();

    for (var root in rootCategories) {
      // Add Root
      categoryItems.add(
        DropdownMenuItem<int>(
          value: root.id,
          child: Row(
            children: [
              Icon(_getIconData(root.icon), color: Color(root.color), size: 20),
              const SizedBox(width: 8),
              Text(root.name, style: const TextStyle(fontWeight: FontWeight.bold)),
            ],
          ),
        ),
      );

      // Add Children
      final children = provider.getSubCategories(root.id!);
      for (var child in children) {
         categoryItems.add(
          DropdownMenuItem<int>(
            value: child.id,
            child: Row(
              children: [
                const SizedBox(width: 24), // Indent
                Icon(_getIconData(child.icon), color: Color(child.color), size: 16),
                const SizedBox(width: 8),
                Text(child.name),
              ],
            ),
          ),
        );
      }
    }

    return Scaffold(
      appBar: AppBar(
        title: const Text('记一笔'),
      ),
      body: Padding(
        padding: const EdgeInsets.all(16.0),
        child: Form(
          key: _formKey,
          child: ListView(
            children: [
              // Type Selection
              RadioGroup<String>(
                groupValue: _transactionType,
                onChanged: (value) {
                  setState(() {
                    _transactionType = value!;
                    _selectedCategoryId = null;
                  });
                },
                child: Row(
                  children: [
                    Expanded(
                      child: RadioListTile<String>(
                        title: const Text('支出'),
                        value: 'expense',
                      ),
                    ),
                    Expanded(
                      child: RadioListTile<String>(
                        title: const Text('收入'),
                        value: 'income',
                      ),
                    ),
                  ],
                ),
              ),
              
              // Amount
              TextFormField(
                controller: _amountController,
                keyboardType: TextInputType.number,
                decoration: const InputDecoration(
                  labelText: '金额',
                  prefixText: '¥ ',
                ),
                validator: (value) {
                  if (value == null || value.isEmpty) {
                    return '请输入金额';
                  }
                  if (double.tryParse(value) == null) {
                    return '请输入有效的数字';
                  }
                  return null;
                },
              ),
              
              const SizedBox(height: 16),

              // Category
              DropdownButtonFormField<int>(
                key: ValueKey(_selectedCategoryId),
                initialValue: _selectedCategoryId,
                decoration: const InputDecoration(labelText: '分类'),
                items: categoryItems,
                onChanged: (value) {
                  setState(() {
                    _selectedCategoryId = value;
                  });
                },
                validator: (value) {
                  if (value == null) {
                    return '请选择分类';
                  }
                  return null;
                },
              ),

              const SizedBox(height: 16),

              // Date Picker
              Row(
                children: [
                  Text('日期: ${DateFormat('yyyy-MM-dd').format(_selectedDate)}'),
                  const Spacer(),
                  TextButton(
                    onPressed: () async {
                      final pickedDate = await showDatePicker(
                        context: context,
                        initialDate: _selectedDate,
                        firstDate: DateTime(2000),
                        lastDate: DateTime(2100),
                        helpText: '选择日期',
                      );
                      if (pickedDate != null) {
                        setState(() {
                          _selectedDate = pickedDate;
                        });
                      }
                    },
                    child: const Text('选择日期'),
                  ),
                ],
              ),

              const SizedBox(height: 16),

              // Note
              TextFormField(
                controller: _noteController,
                decoration: const InputDecoration(labelText: '备注'),
              ),

              const SizedBox(height: 32),

              ElevatedButton(
                onPressed: _saveTransaction,
                style: ElevatedButton.styleFrom(
                  minimumSize: const Size(double.infinity, 50),
                ),
                child: const Text('保存', style: TextStyle(fontSize: 18)),
              ),
            ],
          ),
        ),
      ),
    );
  }

  void _saveTransaction() {
    if (_formKey.currentState!.validate()) {
      final newTransaction = TransactionModel(
        id: const Uuid().v4(),
        amount: double.parse(_amountController.text),
        type: _transactionType,
        categoryId: _selectedCategoryId!,
        date: _selectedDate,
        note: _noteController.text,
        createdAt: DateTime.now(),
        updatedAt: DateTime.now(),
      );

      Provider.of<ExpenseProvider>(context, listen: false).addTransaction(newTransaction);
      Navigator.of(context).pop();
    }
  }

  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;
    }
  }
}