import 'dart:io';

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

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

    if (choiceInput == null) {
      print('Invalid input. Please try again.');
      continue;
    }

    int? choice = int.tryParse(choiceInput);
    if (choice == null) {
      print('Please enter a valid number.');
      continue;
    }

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

    if (choice == 1) {
      _addIncome(incomeList);
    } else if (choice == 2) {
      _addExpense(expenseList);
    } else if (choice == 3) {
      _viewSummary(incomeList, expenseList);
    } else {
      print('Invalid choice. Please try again.');
    }
  }
}

void _addIncome(List<Map<String, double>> incomeList) {
  stdout.write('Enter income description: ');
  String? description = stdin.readLineSync();
  if (description == null || description.trim().isEmpty) {
    print('Description cannot be empty.');
    return;
  }

  double? amount = _readPositiveAmount('Enter income amount: ');
  if (amount == null) {
    return;
  }

  incomeList.add({description.trim(): amount});
  print('Income added!');
}

void _addExpense(List<Map<String, double>> expenseList) {
  stdout.write('Enter expense description: ');
  String? description = stdin.readLineSync();
  if (description == null || description.trim().isEmpty) {
    print('Description cannot be empty.');
    return;
  }

  double? amount = _readPositiveAmount('Enter expense amount: ');
  if (amount == null) {
    return;
  }

  expenseList.add({description.trim(): amount});
  print('Expense added!');
}

double? _readPositiveAmount(String prompt) {
  while (true) {
    stdout.write(prompt);
    String? input = stdin.readLineSync();

    if (input == null) {
      print('Invalid input. Please try again.');
      continue;
    }

    double? value = double.tryParse(input);
    if (value == null) {
      print('Please enter a valid number.');
      continue;
    }

    if (value < 0) {
      print('Amount cannot be negative. Please try again.');
      continue;
    }

    return value;
  }
}

void _viewSummary(
  List<Map<String, double>> incomeList,
  List<Map<String, double>> expenseList,
) {
  double totalIncome = 0;
  for (var entry in incomeList) {
    entry.forEach((_, amount) {
      totalIncome += amount;
    });
  }

  double totalExpenses = 0;
  for (var entry in expenseList) {
    entry.forEach((_, amount) {
      totalExpenses += amount;
    });
  }

  double net = totalIncome - totalExpenses;

  print('\nSummary:');
  print('Total income: \$${totalIncome.toStringAsFixed(2)}');
  print('Total expenses: \$${totalExpenses.toStringAsFixed(2)}');

  if (net > 0) {
    print('Net profit: \$${net.toStringAsFixed(2)}');
  } else if (net < 0) {
    print('Net loss: \$${(-net).toStringAsFixed(2)}');
  } else {
    print('You are breaking even (no profit, no loss).');
  }

  double tax = net > 0 ? net * 0.15 : 0;
  if (tax > 0) {
    print('Tax to be paid: \$${tax.toStringAsFixed(2)}');
  } else {
    print('No tax due (no profit).');
  }
}