import 'dart:io';

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

  print(" Welcome to the Budget Management System!");

  while (true) {
    print("\nChoose an option:");
    print("1. Add Income");
    print("2. Add Expense");
    print("3. View Summary");
    print("4. Exit");

    stdout.write("Enter your choice (1-4): ");
    String? choice = stdin.readLineSync();

    if (choice == '1') {
      addEntry(incomeList, isIncome: true);
    } else if (choice == '2') {
      addEntry(expenseList, isIncome: false);
    } else if (choice == '3') {
      viewSummary(incomeList, expenseList);
    } else if (choice == '4') {
      print(" Exiting the program. Goodbye!");
      break;
    } else {
      print(" Invalid choice. Please enter a number between 1 and 4.");
    }
  }
}

void addEntry(List<Map<String, double>> list, {required bool isIncome}) {
  stdout.write("Enter ${isIncome ? 'income' : 'expense'} description: ");
  String? description = stdin.readLineSync();

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

  if (amount == null || amount < 0) {
    print(" Invalid amount. Please enter a positive number.");
    return;
  }

  list.add({description ?? 'Unnamed': amount});
  print(" ${isIncome ? 'Income' : 'Expense'} added successfully.");
}

void viewSummary(List<Map<String, double>> incomeList, List<Map<String, double>> expenseList) {
  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) {
    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, no loss.");
  }
}