import 'dart:io';

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

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

    if (choice == '4') {
      print('Exiting Budget Manager... Goodbye!');
      break;
    }

    if (choice == '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 ?? 'Income': amount});
        print('Income added successfully.');
      } else {
        print('Invalid amount. Please enter a positive number.');
      }
    } else if (choice == '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 ?? 'Expense': amount});
        print('Expense added successfully.');
      } else {
        print('Invalid amount. Please enter a positive number.');
      }
    } else if (choice == '3') {
      double totalIncome = incomeList.fold(0, (sum, item) => sum + item.values.first);
      double totalExpense = expenseList.fold(0, (sum, item) => sum + item.values.first);
      double net = totalIncome - totalExpense;

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

      if (net > 0) {
        double tax = net * 0.15;
        print('Your net profit is \$${net.toStringAsFixed(2)}');
        print('Tax to be paid (15%): \$${tax.toStringAsFixed(2)}');
      } else if (net < 0) {
        print('Your net loss is \$${(-net).toStringAsFixed(2)}');
      } else {
        print('You broke even — no profit or loss.');
      }
    } else {
      print('Invalid choice! Please select a valid option.');
    }
  }
}