import 'dart:io';

void main() {
  List<Map<String, double>> incomeList = [];
  List<Map<String, double>> expenseList = [];
  const double taxRate = 0.15;

  print('💰 Welcome to Budget Management Application');

  bool running = true;

  while (running) {
    print('\nSelect an option:');
    print('1. Add Income');
    print('2. Add Expense');
    print('3. View Summary');
    print('4. Exit');
    stdout.write('Your choice: ');

    String? choice = stdin.readLineSync();

    switch (choice) {
      case '1':
        stdout.write('Enter income description: ');
        String? desc = stdin.readLineSync();
        stdout.write('Enter income amount: ');
        String? amountInput = stdin.readLineSync();
        double? amount = double.tryParse(amountInput ?? '');
        if (desc != null && amount != null && amount >= 0) {
          incomeList.add({desc: amount});
          print('✅ Income added: $desc - \$${amount.toStringAsFixed(2)}');
        } else {
          print('❌ Invalid input. Please enter a valid description and a positive amount.');
        }
        break;

      case '2':
        stdout.write('Enter expense description: ');
        String? desc = stdin.readLineSync();
        stdout.write('Enter expense amount: ');
        String? amountInput = stdin.readLineSync();
        double? amount = double.tryParse(amountInput ?? '');
        if (desc != null && amount != null && amount >= 0) {
          expenseList.add({desc: amount});
          print('✅ Expense added: $desc - \$${amount.toStringAsFixed(2)}');
        } else {
          print('❌ Invalid input. Please enter a valid description and a positive amount.');
        }
        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)}');
        print(net >= 0
            ? 'Your net profit is \$${net.toStringAsFixed(2)}'
            : 'Your net loss is \$${(-net).toStringAsFixed(2)}');

        // Optional Tax Calculation
        double tax = net > 0 ? net * taxRate : 0;
        if (tax > 0) {
          print('Tax to be paid (15% of net profit): \$${tax.toStringAsFixed(2)}');
        }
        break;

      case '4':
        running = false;
        print('👋 Exiting Budget Management Application. Goodbye!');
        break;

      default:
        print('❌ Invalid option. Please select between 1–4.');
    }
  }
}