import 'dart:io';

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

  while (true) {
    print("\n--- Budget Management System ---");
    print("1. Add Income");
    print("2. Add Expense");
    print("3. View Summary");
    print("4. Exit");
    stdout.write("Choose an option: ");
    String? choice = stdin.readLineSync();

    if (choice == "1") {
      stdout.write("Enter income description: ");
      String? desc = stdin.readLineSync();
      stdout.write("Enter amount: ");
      double? amount = double.tryParse(stdin.readLineSync() ?? "");
      if (amount != null && amount >= 0) {
        incomeList.add({desc ?? "Income": amount});
        print("Income added.");
      } else {
        print("Invalid amount.");
      }

    } else if (choice == "2") {
      stdout.write("Enter expense description: ");
      String? desc = stdin.readLineSync();
      stdout.write("Enter amount: ");
      double? amount = double.tryParse(stdin.readLineSync() ?? "");
      if (amount != null && amount >= 0) {
        expenseList.add({desc ?? "Expense": amount});
        print("Expense added.");
      } else {
        print("Invalid amount.");
      }

    } else if (choice == "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--- Summary ---");
      print("Total Income: \$${totalIncome}");
      print("Total Expenses: \$${totalExpenses}");
      print(net >= 0 ? "Net Profit: \$${net}" : "Net Loss: \$${net.abs()}");

      if (net > 0) {
        double tax = net * 0.15;
        print("Tax to Pay (15%): \$${tax}");
      }

    } else if (choice == "4") {
      print("Goodbye!");
      break;
    } else {
      print("Invalid choice.");
    }
  }
}