import 'dart:io';

void main() {
  // Welcome message
  print("Welcome to Budget Management System");
  print("------------------------------------");

  // Lists to store income and expenses
  List<Map<String, double>> incomeList = [];
  List<Map<String, double>> expenseList = [];

  // Loop for menu
  while (true) {
    print("\nMenu:");
    print("1. Add Income");
    print("2. Add Expense");
    print("3. View Summary");
    print("4. Exit");

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

    // Add income
    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: amount});
        print("Income added successfully.");
      } else {
        print("Invalid amount!");
      }
    }

    // Add expense
    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: amount});
        print("Expense added successfully.");
      } else {
        print("Invalid amount!");
      }
    }

    // View summary
    else if (choice == '3') {
      double totalIncome = 0;
      double totalExpense = 0;

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

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

      double net = totalIncome - totalExpense;

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

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

        // Optional tax (15%) using ternary
        double tax = net > 0 ? net * 0.15 : 0;
        if (tax > 0) {
          print("Tax to pay (15%): \$${tax}");
        }
      } else {
        print("Your net loss is \$${net.abs()}");
      }
    }

    // Exit
    else if (choice == '4') {
      print("Thank you for using Budget Management System");
      break;
    }

    else {
      print("Invalid choice, try again.");
    }
  }
}