import 'dart:io';

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

  bool running = true;

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

  while (running) {
    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();

    switch (choice) {
      case '1':
        // Handle Income
        stdout.write('Enter income description: ');
        String desc = stdin.readLineSync() ?? 'Untitled Income';
        
        stdout.write('Enter income amount: ');
        double? amount = double.tryParse(stdin.readLineSync() ?? '');

        if (amount != null && amount >= 0) {
          incomeList.add({'description': desc, 'amount': amount});
          print('Income added!');
        } else {
          print('Invalid amount. Please enter a positive number.');
        }
        break;

      case '2':
        // Handle Expenses
        stdout.write('Enter expense description: ');
        String desc = stdin.readLineSync() ?? 'Untitled Expense';
        
        stdout.write('Enter expense amount: ');
        double? amount = double.tryParse(stdin.readLineSync() ?? '');

        if (amount != null && amount >= 0) {
          expenseList.add({'description': desc, 'amount': amount});
          print('Expense added!');
        } else {
          print('Invalid amount. Please enter a positive number.');
        }
        break;

      case '3':
        // View Summary & Calculations
        double totalIncome = 0;
        double totalExpenses = 0;

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

        double netResult = totalIncome - totalExpenses;
        
        // Tax Calculation using Ternary Operator
        // Tax is 15% of net profit, only if profit > 0
        double tax = netResult > 0 ? netResult * 0.15 : 0.0;

        print('\nSummary:');
        print('Total income: \$${totalIncome.toStringAsFixed(0)}');
        print('Total expenses: \$${totalExpenses.toStringAsFixed(0)}');

        if (netResult >= 0) {
          print('Net profit: \$${netResult.toStringAsFixed(0)}');
          print('Tax to be paid: \$${tax.toStringAsFixed(0)}');
        } else {
          print('Net loss: \$${netResult.abs().toStringAsFixed(0)}');
          print('No tax to be paid on losses.');
        }
        break;

      case '4':
        print('Exiting the application. Goodbye!');
        running = false;
        break;

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