import 'dart:io';

void main() {

  List<Map<String, double>> incomeList = [];
  List<Map<String, double>> expenseList = [];

  bool running = true;

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

  while (running) {

    print("\nChoose an option:");
    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.");
      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) {

        incomeList.add({description: amount});
        print("Income added successfully.");

      } else {
        print("Invalid amount. Please enter a positive number.");
      }

    } 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) {

        expenseList.add({description: amount});
        print("Expense added successfully.");

      } else {
        print("Invalid amount. Please enter a positive number.");
      }

    } else if (choice == 3) {

      double totalIncome = 0;
      double totalExpenses = 0;

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

      for (var expense in expenseList) {
        totalExpenses += expense.values.first;
      }

      double net = totalIncome - totalExpenses;

      print("\n===== Budget Summary =====");
      print("Total Income: \$${totalIncome}");
      print("Total Expenses: \$${totalExpenses}");

      if (net >= 0) {
        print("Your net profit is \$${net}");

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

      } else {
        print("Your net loss is \$${net.abs()}");
      }

    } else if (choice == 4) {

      print("Exiting the program. Goodbye!");
      running = false;

    } else {

      print("Invalid choice. Please try again.");
    }
  }
}