import 'dart:io';

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

  print('Welcome to the Budget Management Application!');

  while (true) {
    print('\nPlease choose an option:');
    print('1. Add income');
    print('2. Add expense');
    print('3. View summary');
    print('4. Exit');

    String? input = stdin.readLineSync();
    int? choice = int.tryParse(input ?? '');

    switch (choice) {
      case 1:
        addEntry(incomeList, 'income');
        break;

      case 2:
        addEntry(expenseList, 'expense');
        break;

      case 3:
        viewSummary(incomeList, expenseList);
        break;

      case 4:
        print('Exiting the application. Goodbye!');
        return;

      default:
        print('Invalid choice. Please try again.');
    }
  }
}

void addEntry(List<Map<String, dynamic>> list, String type) {
  print('Enter ${type} description:');
  String? description = stdin.readLineSync();
  print('Enter ${type} amount:');
  String? amountInput = stdin.readLineSync();
  double? amount = double.tryParse(amountInput ?? '');

  if (description != null && description.isNotEmpty && amount != null && amount > 0) {
    list.add({'description': description, 'amount': amount});
    print('${type.capitalize()} added!');
  } else {
    print('Invalid input. Please enter a valid description and positive amount.');
  }
}

void viewSummary(List<Map<String, dynamic>> incomeList, List<Map<String, dynamic>> expenseList) {
  double totalIncome = 0;
  double totalExpense = 0;

  for (var entry in incomeList) {
    totalIncome += entry['amount'];
  }

  for (var entry in expenseList) {
    totalExpense += entry['amount'];
  }

  double net = totalIncome - totalExpense;
  double tax = net > 0 ? net * 0.15 : 0;

  print('\nSummary:');
  print('Total income: \$${totalIncome.toStringAsFixed(2)}');
  print('Total expenses: \$${totalExpense.toStringAsFixed(2)}');
  print('Net ${net >= 0 ? 'profit' : 'loss'}: \$${net.abs().toStringAsFixed(2)}');
  if (net > 0) {
    print('Tax to be paid: \$${tax.toStringAsFixed(2)}');
  }
}

extension StringExtension on String {
  String capitalize() {
    return "${this[0].toUpperCase()}${this.substring(1)}";
  }
}