import 'dart:io';

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

  while (true) {
    stdout.writeln('\n=== Budget Manager ===');
    stdout.writeln('1) Add income');
    stdout.writeln('2) Add expense');
    stdout.writeln('3) Show summary');
    stdout.writeln('4) Exit');
    stdout.write('Your choice: ');
    final choice = stdin.readLineSync()?.trim() ?? '';

    if (choice == '1') {
      stdout.write('Income description: ');
      final desc = stdin.readLineSync()?.trim() ?? '';
      stdout.write('Amount: ');
      final amt = double.tryParse(stdin.readLineSync()?.trim() ?? '');
      if (desc.isNotEmpty && amt != null && amt >= 0) {
        incomeList.add({desc: amt});
        stdout.writeln('Added.');
      } else {
        stdout.writeln('Invalid data. Amount must be a number ≥ 0.');
      }
    } else if (choice == '2') {
      stdout.write('Expense description: ');
      final desc = stdin.readLineSync()?.trim() ?? '';
      stdout.write('Amount: ');
      final amt = double.tryParse(stdin.readLineSync()?.trim() ?? '');
      if (desc.isNotEmpty && amt != null && amt >= 0) {
        expenseList.add({desc: amt});
        stdout.writeln('Added.');
      } else {
        stdout.writeln('Invalid data. Amount must be a number ≥ 0.');
      }
    } else if (choice == '3') {
      final totalIncome = _sum(incomeList);
      final totalExpense = _sum(expenseList);
      final net = totalIncome - totalExpense;
      final profitable = net > 0;
      final tax = profitable ? net * 0.15 : 0.0;

      stdout.writeln('\n--- Summary ---');
      stdout.writeln('Total income: ${totalIncome.toStringAsFixed(2)}');
      stdout.writeln('Total expense: ${totalExpense.toStringAsFixed(2)}');
      if (profitable) {
        stdout.writeln('Net profit: ${net.toStringAsFixed(2)}');
        stdout.writeln('Tax due 15%: ${tax.toStringAsFixed(2)}');
      } else if (net < 0) {
        stdout.writeln('Net loss: ${(-net).toStringAsFixed(2)}');
      } else {
        stdout.writeln('Break-even.');
      }
    } else if (choice == '4') {
      stdout.writeln('Exited.');
      return;
    } else {
      stdout.writeln('Invalid choice.');
    }
  }
}

double _sum(List<Map<String, double>> items) {
  var s = 0.0;
  for (final m in items) {
    for (final entry in m.entries) {
      s += entry.value;
    }
  }
  return s;
}