import 'package:flutter/material.dart';
import 'package:drift/drift.dart' show Value;
import 'package:intl/intl.dart';

import '../database/database.dart' as db;
import '../utils/category_utils.dart'; // For icon and color utilities

class EditTransactionDialog extends StatefulWidget {
  final db.AppDatabase database;
  final db.Transaction transaction; // The transaction to edit
  final Stream<List<db.CategoryDb>> categoriesStream; // Stream of available categories

  const EditTransactionDialog({
    Key? key,
    required this.database,
    required this.transaction,
    required this.categoriesStream,
  }) : super(key: key);

  @override
  State<EditTransactionDialog> createState() => _EditTransactionDialogState();
}

class _EditTransactionDialogState extends State<EditTransactionDialog> {
  final _formKey = GlobalKey<FormState>();
  late TextEditingController _amountController;
  late TextEditingController _merchantController;
  late String? _selectedCategoryName; // Can be null for Income
  late DateTime _selectedDate;
  late db.TransactionType _selectedType;

  @override
  void initState() {
    super.initState();
    // Initialize controllers and state with existing transaction data
    _amountController = TextEditingController(text: widget.transaction.amount.toString());
    _merchantController = TextEditingController(text: widget.transaction.merchant);
    _selectedDate = widget.transaction.date;
    _selectedType = widget.transaction.type == 'income' ? db.TransactionType.income : db.TransactionType.expense;

    // Set initial category name based on transaction type
    if (_selectedType == db.TransactionType.expense) {
      _selectedCategoryName = widget.transaction.categoryName;
    } else {
      _selectedCategoryName = null; // Income doesn't have a selectable category
    }
  }

  @override
  void dispose() {
    _amountController.dispose();
    _merchantController.dispose();
    super.dispose();
  }

  // Function to show the date and time pickers
  Future<void> _selectDateTime(BuildContext context) async {
    // 1. Pick Date
    final DateTime? pickedDate = await showDatePicker(
      context: context,
      initialDate: _selectedDate,
      firstDate: DateTime(2000),
      lastDate: DateTime.now().add(const Duration(days: 365)),
    );

    if (pickedDate != null) {
      // If date was picked, proceed to pick time
      // 2. Pick Time
      final TimeOfDay? pickedTime = await showTimePicker(
        context: context,
        initialTime: TimeOfDay.fromDateTime(_selectedDate),
      );

      if (pickedTime != null) {
        // If time was also picked, combine date and time and update state
        setState(() {
          _selectedDate = DateTime(
            pickedDate.year,
            pickedDate.month,
            pickedDate.day,
            pickedTime.hour,
            pickedTime.minute,
          );
        });
      } else {
         // If only date was picked, update state with the picked date and existing time
         setState(() {
           _selectedDate = DateTime(
             pickedDate.year,
             pickedDate.month,
             pickedDate.day,
             _selectedDate.hour, // Keep existing hour
             _selectedDate.minute, // Keep existing minute
           );
         });
      }
    }
  }

  // Function to handle form submission (Update)
  void _updateTransaction() async {
    if (_formKey.currentState!.validate()) {
      final amount = double.tryParse(_amountController.text);
      if (amount == null || amount <= 0) {
        ScaffoldMessenger.of(context).showSnackBar(
          const SnackBar(
            content: Text('Пожалуйста, введите корректную положительную сумму.'),
            backgroundColor: Colors.red,
          ),
        );
        return;
      }

      String categoryToSave;
      String typeString = _selectedType == db.TransactionType.income ? 'income' : 'expense';

      if (_selectedType == db.TransactionType.income) {
        categoryToSave = 'Income'; // Fixed category for income
      } else {
        if (_selectedCategoryName == null) {
           ScaffoldMessenger.of(context).showSnackBar(
             const SnackBar(
               content: Text('Пожалуйста, выберите категорию для расхода.'),
               backgroundColor: Colors.red,
             ),
           );
           return;
        }
        categoryToSave = _selectedCategoryName!;
      }

      // Create the updated transaction companion
      final updatedTransaction = db.TransactionsCompanion(
        id: Value(widget.transaction.id), // Include the ID for update
        categoryName: Value(categoryToSave),
        amount: Value(amount),
        date: Value(_selectedDate),
        merchant: Value(_merchantController.text),
        type: Value(typeString),
      );

      try {
        // Update transaction in the database
        final success = await widget.database.updateTransaction(updatedTransaction);

        if (success) {
          // Close the dialog and return the updated transaction
          if (mounted) Navigator.of(context).pop(widget.transaction.copyWith( // Return a copy with updated values
             categoryName: categoryToSave,
             amount: amount,
             date: _selectedDate,
             merchant: _merchantController.text,
             type: typeString,
          ));
        } else {
           if (mounted) {
             ScaffoldMessenger.of(context).showSnackBar(
               const SnackBar(
                 content: Text('Не удалось обновить транзакцию.'),
                 backgroundColor: Colors.red,
               ),
             );
           }
        }
      } catch (e) {
        print('Error updating transaction: $e');
        if (mounted) {
          ScaffoldMessenger.of(context).showSnackBar(
            SnackBar(
              content: Text('Ошибка при обновлении транзакции: $e'),
              backgroundColor: Colors.red,
            ),
          );
        }
      }
    }
  }

  @override
  Widget build(BuildContext context) {
    final theme = Theme.of(context);
    final isDark = theme.brightness == Brightness.dark;
    final bool isIncome = _selectedType == db.TransactionType.income;

    return AlertDialog(
      title: const Text('Редактировать транзакцию'),
      content: SingleChildScrollView( // Use SingleChildScrollView for content
        child: Form(
          key: _formKey,
          child: Column(
            mainAxisSize: MainAxisSize.min,
            crossAxisAlignment: CrossAxisAlignment.start,
            children: <Widget>[
              // --- Transaction Type Selector ---
              Center(
                child: ToggleButtons(
                  isSelected: [!isIncome, isIncome],
                  onPressed: (int index) {
                    setState(() {
                      _selectedType = index == 0 ? db.TransactionType.expense : db.TransactionType.income;
                      // Reset category selection if switching to income
                      if (_selectedType == db.TransactionType.income) {
                        _selectedCategoryName = null;
                      } else {
                         // If switching to expense, try to select the first expense category
                         // This relies on the StreamBuilder below to update the dropdown
                         // and potentially set a default if _selectedCategoryName is null.
                      }
                    });
                  },
                  borderRadius: BorderRadius.circular(12),
                  // ИЗМЕНЕНО: Уменьшена минимальная ширина кнопок
                  constraints: BoxConstraints(minWidth: (MediaQuery.of(context).size.width - 160) / 2, minHeight: 40), // Adjusted width for dialog
                  selectedColor: Colors.white,
                  fillColor: isIncome ? Colors.green.shade400 : Colors.red.shade400,
                  color: isDark ? Colors.white70 : Colors.black54,
                  selectedBorderColor: isIncome ? Colors.green.shade600 : Colors.red.shade600,
                  borderColor: isDark ? Colors.grey.shade600 : Colors.grey.shade400,
                  children: const <Widget>[
                    Padding(
                      padding: EdgeInsets.symmetric(horizontal: 16.0),
                      child: Row(
                        mainAxisSize: MainAxisSize.min,
                        children: [ Icon(Icons.arrow_upward_rounded, size: 18), SizedBox(width: 8), Text('Расход'), ],
                      ),
                    ),
                    Padding(
                      padding: EdgeInsets.symmetric(horizontal: 16.0),
                      child: Row(
                        mainAxisSize: MainAxisSize.min,
                        children: [ Icon(Icons.arrow_downward_rounded, size: 18), SizedBox(width: 8), Text('Доход'), ],
                      ),
                    ),
                  ],
                ),
              ),
              const SizedBox(height: 20),

              // --- Amount Field ---
              TextFormField(
                controller: _amountController,
                decoration: InputDecoration(
                  labelText: 'Сумма',
                  prefixIcon: Icon(Icons.attach_money, color: isIncome ? Colors.green : theme.colorScheme.primary),
                  border: OutlineInputBorder(borderRadius: BorderRadius.circular(12)),
                  filled: true,
                  fillColor: isDark ? Colors.grey.shade800.withOpacity(0.5) : Colors.grey.shade100,
                ),
                keyboardType: const TextInputType.numberWithOptions(decimal: true),
                validator: (value) {
                  if (value == null || value.isEmpty) {
                    return 'Пожалуйста, введите сумму';
                  }
                  if (double.tryParse(value) == null || double.parse(value) <= 0) {
                    return 'Пожалуйста, введите корректное положительное число';
                  }
                  return null;
                },
              ),
              const SizedBox(height: 16),

              // --- Category Dropdown (Only for Expenses, uses StreamBuilder) ---
              if (!isIncome)
                StreamBuilder<List<db.CategoryDb>>(
                  stream: widget.categoriesStream,
                  builder: (context, snapshot) {
                    if (snapshot.connectionState == ConnectionState.waiting && !snapshot.hasData) {
                      return const Center(child: CircularProgressIndicator(strokeWidth: 2));
                    }
                    if (snapshot.hasError) {
                      return Text('Ошибка загрузки категорий: ${snapshot.error}');
                    }

                    final categoriesFromDb = snapshot.data ?? [];
                    // Filter out 'Income' category for the dropdown
                    final expenseCategories = categoriesFromDb.where((c) => c.name != 'Income').toList();

                    // Ensure _selectedCategoryName is valid or reset it
                    if (_selectedCategoryName != null && !expenseCategories.any((c) => c.name == _selectedCategoryName)) {
                       _selectedCategoryName = null; // Reset if selected category is no longer valid
                    }
                    // Set default selection if nothing is selected and list is not empty
                    // This handles the case when switching from Income to Expense
                    if (_selectedCategoryName == null && expenseCategories.isNotEmpty) {
                       // Use WidgetsBinding to schedule state update after build
                       WidgetsBinding.instance.addPostFrameCallback((_) {
                         if (mounted) { // Check if widget is still mounted
                           setState(() {
                             _selectedCategoryName = expenseCategories[0].name;
                           });
                         }
                       });
                    }


                    return DropdownButtonFormField<String>(
                      value: _selectedCategoryName,
                      decoration: InputDecoration(
                        labelText: 'Категория',
                        border: OutlineInputBorder(borderRadius: BorderRadius.circular(12)),
                        filled: true,
                        fillColor: isDark ? Colors.grey.shade800.withOpacity(0.5) : Colors.grey.shade100,
                        contentPadding: const EdgeInsets.symmetric(horizontal: 12.0, vertical: 16.0),
                      ),
                      items: expenseCategories.map((db.CategoryDb category) {
                        final iconData = CategoryUtils.getIconFromString(category.icon);
                        final colorData = Color(category.color);
                        return DropdownMenuItem<String>(
                          value: category.name,
                          child: Row(
                            children: [
                              Icon(iconData, color: colorData, size: 20),
                              const SizedBox(width: 10),
                              Text(category.name),
                            ],
                          ),
                        );
                      }).toList(),
                      onChanged: (String? newValue) {
                        setState(() {
                          _selectedCategoryName = newValue;
                        });
                      },
                      validator: (value) {
                        if (_selectedType == db.TransactionType.expense && value == null) {
                          return 'Пожалуйста, выберите категорию';
                        }
                        return null;
                      },
                    );
                  },
                ),
              if (!isIncome) const SizedBox(height: 16),

              // --- Date and Time Picker ---
              InkWell(
                onTap: () => _selectDateTime(context),
                child: InputDecorator(
                  decoration: InputDecoration(
                    labelText: 'Дата и время',
                    prefixIcon: const Icon(Icons.calendar_today_outlined),
                    border: OutlineInputBorder(borderRadius: BorderRadius.circular(12)),
                    filled: true,
                    fillColor: isDark ? Colors.grey.shade800.withOpacity(0.5) : Colors.grey.shade100,
                  ),
                  child: Text(
                    DateFormat.yMMMd().add_jm().format(_selectedDate),
                    style: theme.textTheme.bodyLarge,
                  ),
                ),
              ),
              const SizedBox(height: 16),

              // --- Merchant / Source Field ---
              TextFormField(
                controller: _merchantController,
                decoration: InputDecoration(
                  labelText: isIncome ? 'Источник' : 'Продавец / Магазин',
                  prefixIcon: Icon(isIncome ? Icons.source_outlined : Icons.storefront_outlined),
                  border: OutlineInputBorder(borderRadius: BorderRadius.circular(12)),
                  filled: true,
                  fillColor: isDark ? Colors.grey.shade800.withOpacity(0.5) : Colors.grey.shade100,
                ),
                textCapitalization: TextCapitalization.words,
              ),
            ],
          ),
        ),
      ),
      actions: <Widget>[
        TextButton(
          onPressed: () => Navigator.of(context).pop(), // Close dialog
          child: const Text('Отмена'),
        ),
        ElevatedButton(
          onPressed: _updateTransaction, // Call update function
          child: const Text('Сохранить'),
        ),
      ],
    );
  }
}