import 'dart:io';

void main() {
  List<Map<String, double>> incomeList = [];
  List<Map<String, double>> expenseList = [];

  while (true) {
    print('\n=== Budget Management Menu ===');
    print('1. Add Income');
    print('2. Add Expense');
    print('3. View Summary');
    print('4. Exit');
    stdout.write('Enter your choice: ');
    String? choice = stdin.readLineSync();

    switch (choice) {
      case '1':
        stdout.write('Enter income description: ');
        String? desc = stdin.readLineSync();
        stdout.write('Enter income amount: ');
        double? amount = double.tryParse(stdin.readLineSync()!);
        if (amount != null && amount >= 0) {
          incomeList.add({desc!: amount});
          print('Income added.');
        } else {
          print('Invalid amount. Please enter a non-negative number.');
        }
        break;

      case '2':
        stdout.write('Enter expense description: ');
        String? desc = stdin.readLineSync();
        stdout.write('Enter expense amount: ');
        double? amount = double.tryParse(stdin.readLineSync()!);
        if (amount != null && amount >= 0) {
          expenseList.add({desc!: amount});
          print('Expense added.');
        } else {
          print('Invalid amount. Please enter a non-negative number.');
        }
        break;

      case '3':
        double totalIncome = incomeList.fold(0, (sum, item) => sum + item.values.first);
        double totalExpenses = expenseList.fold(0, (sum, item) => sum + item.values.first);
        double net = totalIncome - totalExpenses;

        print('\n--- Budget Summary ---');
        print('Total Income: \$${totalIncome.toStringAsFixed(2)}');
        print('Total Expenses: \$${totalExpenses.toStringAsFixed(2)}');

        if (net >= 0) {
          print('Your net profit is \$${net.toStringAsFixed(2)}');
          // Optional tax feature
          double tax = net * 0.15;
          print('Tax to be paid (15%): \$${tax.toStringAsFixed(2)}');
        } else {
          print('Your net loss is \$${(-net).toStringAsFixed(2)}');
        }
        break;

      case '4':
        print('Exiting Budget App. Goodbye!');
        return;

      default:
        print('Invalid choice. Please select a valid option.');
    }
  }
}