import 'dart:io';

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

  while (true) {
    print('\nWelcome to the Budget Management Application!');
    print('1. Add income');
    print('2. Add expense');
    print('3. View summary');
    print('4. Exit');

    stdout.write('Enter your choice: ');
    int? choice = int.tryParse(stdin.readLineSync() ?? '');

    if (choice == null) {
      print('Invalid input. Please enter a number from 1 to 4.');
      continue;
    }

    if (choice == 1) {
      stdout.write('Enter income description: ');
      String description = stdin.readLineSync() ?? '';

      stdout.write('Enter income amount: ');
      double? amount = double.tryParse(stdin.readLineSync() ?? '');

      if (amount == null || amount < 0) {
        print('Invalid amount. Please enter a positive number.');
      } else {
        incomeList.add({
          'description': description,
          'amount': amount,
        });
        print('Income added!');
      }
    } else if (choice == 2) {
      stdout.write('Enter expense description: ');
      String description = stdin.readLineSync() ?? '';

      stdout.write('Enter expense amount: ');
      double? amount = double.tryParse(stdin.readLineSync() ?? '');

      if (amount == null || amount < 0) {
        print('Invalid amount. Please enter a positive number.');
      } else {
        expenseList.add({
          'description': description,
          'amount': amount,
        });
        print('Expense added!');
      }
    } else if (choice == 3) {
      double totalIncome = 0;
      double totalExpenses = 0;

      for (var income in incomeList) {
        totalIncome += income['amount'];
      }

      for (var expense in expenseList) {
        totalExpenses += expense['amount'];
      }

      double net = totalIncome - totalExpenses;
      double tax = net > 0 ? net * 0.15 : 0;

      print('\nSummary:');
      print('Total income: \$${totalIncome.toStringAsFixed(2)}');
      print('Total expenses: \$${totalExpenses.toStringAsFixed(2)}');

      if (net >= 0) {
        print('Net profit: \$${net.toStringAsFixed(2)}');
        print('Tax to be paid: \$${tax.toStringAsFixed(2)}');
      } else {
        print('Net loss: \$${net.abs().toStringAsFixed(2)}');
      }
    } else if (choice == 4) {
      print('Exiting the application. Goodbye!');
      break;
    } else {
      print('Invalid choice. Please select from 1 to 4.');
    }
  }
}