import 'dart:io';

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

  while (true) {
    print("\nBudget 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()!);

    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!");
        }
        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!");
        }
        break;

      case 3:
        double totalIncome = 0;
        double totalExpense = 0;

        for (var item in incomeList) {
          totalIncome += item.values.first;
        }

        for (var item in expenseList) {
          totalExpense += item.values.first;
        }

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

        print("\nSummary:");
        print("Total income: \$${totalIncome}");
        print("Total expenses: \$${totalExpense}");
        print("Net: \$${net}");

        if (net > 0) {
          print("Tax to be paid: \$${tax}");
        } else {
          print("No tax (loss)");
        }
        break;

      case 4:
        print("Exiting... Goodbye!");
        return;

      default:
        print("Invalid choice!");
    }
  }
}