import 'dart:io';

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

  bool isRunning = true;

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

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

    stdout.write('\nEnter your choice: ');
    String choice = stdin.readLineSync()?.trim() ?? '';

    if (choice == '1') {
      addIncome(incomeList);
    } else if (choice == '2') {
      addExpense(expenseList);
    } else if (choice == '3') {
      viewSummary(incomeList, expenseList);
    } else if (choice == '4') {
      print('Exiting the application. Goodbye!');
      isRunning = false;
    } else {
      print('Invalid choice. Please try again.');
    }
  }
}

void addIncome(List<Map<String, dynamic>> incomeList) {
  stdout.write('Enter income description: ');
  String description = stdin.readLineSync()?.trim() ?? '';

  double amount = readValidAmount('Enter income amount: ');

  incomeList.add({
    'description': description,
    'amount': amount,
  });

  print('Income added!');
}

void addExpense(List<Map<String, dynamic>> expenseList) {
  stdout.write('Enter expense description: ');
  String description = stdin.readLineSync()?.trim() ?? '';

  double amount = readValidAmount('Enter expense amount: ');

  expenseList.add({
    'description': description,
    'amount': amount,
  });

  print('Expense added!');
}

double readValidAmount(String message) {
  while (true) {
    stdout.write(message);
    String input = stdin.readLineSync()?.trim() ?? '';
    double? amount = double.tryParse(input);

    if (amount != null && amount >= 0) {
      return amount;
    } else {
      print('Invalid amount. Please enter a non-negative number.');
    }
  }
}

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

  for (int i = 0; i < incomeList.length; i++) {
    totalIncome += incomeList[i]['amount'];
  }

  for (int i = 0; i < expenseList.length; i++) {
    totalExpenses += expenseList[i]['amount'];
  }

  double netResult = totalIncome - totalExpenses;
  double tax = netResult > 0 ? netResult * 0.15 : 0;

  print('\nSummary:');
  print('Total income: \$${formatAmount(totalIncome)}');
  print('Total expenses: \$${formatAmount(totalExpenses)}');

  if (netResult > 0) {
    print('Net profit: \$${formatAmount(netResult)}');
    print('Tax to be paid: \$${formatAmount(tax)}');
  } else if (netResult < 0) {
    print('Net loss: \$${formatAmount(netResult.abs())}');
  } else {
    print('Net profit: \$0');
  }
}

String formatAmount(double amount) {
  if (amount == amount.roundToDouble()) {
    return amount.toStringAsFixed(0);
  } else {
    return amount.toStringAsFixed(2);
  }
}