import 'dart:io';

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

void main() {
  print('Welcome to Budget Manager!');
  String? input;

  while (true) {
    showOptions();
    input = stdin.readLineSync();

    if (input == '1') {
      handleEntry(incomeList, 'income');
    } else if (input == '2') {
      handleEntry(expenseList, 'expense');
    } else if (input == '3') {
      summarizeBudget();
    } else if (input == '4') {
      print('Goodbye!');
      break;
    } else {
      print('Invalid option.');
    }
  }
}

void showOptions() {
  print('\nSelect an option:');
  print('1. Add income');
  print('2. Add expense');
  print('3. View summary');
  print('4. Exit');
  stdout.write('Choice: ');
}

void handleEntry(List<Map<String, dynamic>> list, String type) {
  stdout.write('Enter $type description: ');
  String? desc = stdin.readLineSync();

  stdout.write('Enter $type amount: ');
  double? amount = double.tryParse(stdin.readLineSync() ?? '');

  if (amount != null && amount >= 0) {
    list.add({'description': desc ?? 'Unnamed', 'amount': amount});
    print('$type added: ${desc ?? 'Unnamed'} - \$${amount.toStringAsFixed(2)}');
  } else {
    print('Invalid amount.');
  }
}

void summarizeBudget() {
  double totalIncome = incomeList.fold(0, (sum, item) => sum + item['amount']);
  double totalExpense = expenseList.fold(0, (sum, item) => sum + item['amount']);
  double net = totalIncome - totalExpense;

  print('\n--- Budget Summary ---');
  print('Income: \$${totalIncome.toStringAsFixed(2)}');
  print('Expenses: \$${totalExpense.toStringAsFixed(2)}');

  if (net >= 0) {
    print('Net profit: \$${net.toStringAsFixed(2)}');
    double tax = net > 0 ? net * 0.15 : 0;
    print('Tax to be paid: \$${tax.toStringAsFixed(2)}');
  } else {
    print('Net loss: \$${net.abs().toStringAsFixed(2)}');
  }
}