import 'dart:io';

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

  print('===== Welcome to Budget Management App =====');

  while (true) {
    print('\n1. Add Income');
    print('2. Add Expense');
    print('3. View Summary');
    print('4. Exit');
    stdout.write('Choose an option: ');
    String? choice = stdin.readLineSync();

    if (choice == '4') {
      print('Exiting Budget Management App. Goodbye!');
      break;
    }

    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 ?? 'Unnamed Income': amount});
          print('Income added successfully.');
        } else {
          print('Invalid amount! Please enter a positive number.');
        }
        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 ?? 'Unnamed Expense': amount});
          print('Expense added successfully.');
        } else {
          print('Invalid amount! Please enter a positive number.');
        }
        break;

      case '3':
        double totalIncome = 0;
        double totalExpenses = 0;

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

        for (var entry in expenseList) {
          totalExpenses += entry.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 or loss.');
        }
        break;

      default:
        print('Invalid choice! Please select a valid option.');
    }
  }
}