// budget.dart
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');

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

    if (choice == null) continue;

    switch (choice.trim()) {
      case '1':
        _addIncome(incomeList);
        break;
      case '2':
        _addExpense(expenseList);
        break;
      case '3':
        _viewSummary(incomeList, expenseList);
        break;
      case '4':
        print('\nExiting the application. Goodbye!');
        return;
      default:
        print('Invalid choice. Please enter 1, 2, 3, or 4.');
    }
  }
}

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

  stdout.write('Enter income amount: ');
  String? amtStr = stdin.readLineSync();
  double? amount = _parsePositiveDouble(amtStr);
  if (amount == null) {
    print('Invalid amount. Income not added.');
    return;
  }

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

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

  stdout.write('Enter expense amount: ');
  String? amtStr = stdin.readLineSync();
  double? amount = _parsePositiveDouble(amtStr);
  if (amount == null) {
    print('Invalid amount. Expense not added.');
    return;
  }

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

double? _parsePositiveDouble(String? input) {
  if (input == null) return null;
  double? val = double.tryParse(input.trim());
  if (val == null) return null;
  if (val < 0) return null;
  return val;
}

void _viewSummary(List<Map<String, dynamic>> incomeList, List<Map<String, dynamic>> expenseList) {
  double totalIncome = incomeList.fold(0.0, (sum, item) => sum + (item['amount'] as double));
  double totalExpenses = expenseList.fold(0.0, (sum, item) => sum + (item['amount'] as double));
  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)}');
    double tax = net > 0 ? net * 0.15 : 0.0;
    if (tax > 0) {
      print('Tax to be paid (15%): \$${tax.toStringAsFixed(2)}');
    } else {
      print('No tax to be paid.');
    }
  } else {
    print('Net loss: \$${(-net).toStringAsFixed(2)}');
    print('No tax (business made a loss).');
  }
}