import 'dart:io';

void main() {
  print('=== Budget Management Application ===');

  List<Map<String, dynamic>> incomes = [];
  List<Map<String, dynamic>> expenses = [];

  while (true) {
    print('\nChoose an option:');
    print('1) Add Income');
    print('2) Add Expense');
    print('3) Show Summary');
    print('4) Exit');
    stdout.write('> ');
    String? choice = stdin.readLineSync();
    if (choice == null) continue;

    if (choice == '4') {
      print('Exiting... Goodbye ');
      break;
    }

    if (choice == '1') {
      stdout.write('Enter income description: ');
      String? desc = stdin.readLineSync();
      stdout.write('Enter amount: ');
      String? amountStr = stdin.readLineSync();
      double? amount = double.tryParse(amountStr ?? '');
      if (desc == null || desc.trim().isEmpty || amount == null || amount < 0) {
        print('Invalid input. Please enter a valid description and positive amount.');
        continue;
      }
      incomes.add({'description': desc.trim(), 'amount': amount});
      print('Income added.');
    } else if (choice == '2') {
      stdout.write('Enter expense description: ');
      String? desc = stdin.readLineSync();
      stdout.write('Enter amount: ');
      String? amountStr = stdin.readLineSync();
      double? amount = double.tryParse(amountStr ?? '');
      if (desc == null || desc.trim().isEmpty || amount == null || amount < 0) {
        print('Invalid input. Please enter a valid description and positive amount.');
        continue;
      }
      expenses.add({'description': desc.trim(), 'amount': amount});
      print('Expense added.');
    } else if (choice == '3') {
      double totalIncome = incomes.fold(0.0, (p, e) => p + (e['amount'] as double));
      double totalExpense = expenses.fold(0.0, (p, e) => p + (e['amount'] as double));
      double net = totalIncome - totalExpense;

      print('\n--- Summary ---');
      print('Total Income: \$${totalIncome.toStringAsFixed(2)}');
      print('Total Expenses: \$${totalExpense.toStringAsFixed(2)}');
      if (net >= 0) {
        print('Net Profit: \$${net.toStringAsFixed(2)}');
      } else {
        print('Net Loss: \$${(net.abs()).toStringAsFixed(2)}');
      }

      double tax = net > 0 ? net * 0.15 : 0.0;
      print(net > 0
          ? 'Tax to pay (15%): \$${tax.toStringAsFixed(2)}'
          : 'No tax (no profit).');

      if (incomes.isNotEmpty) {
        print('\nIncomes:');
        for (var i = 0; i < incomes.length; i++) {
          var it = incomes[i];
          print('${i + 1}. ${it['description']} - \$${(it['amount'] as double).toStringAsFixed(2)}');
        }
      }

      if (expenses.isNotEmpty) {
        print('\nExpenses:');
        for (var i = 0; i < expenses.length; i++) {
          var it = expenses[i];
          print('${i + 1}. ${it['description']} - \$${(it['amount'] as double).toStringAsFixed(2)}');
        }
      }
      print('----------------');
    } else {
      print('Invalid option. Please try again.');
    }
  }
}