import 'dart:io';

 void main() {
  // Welcome message
  print('Welcome to the Budget Management Application!');

  // Data storage: Lists of maps for incomes and expenses
  List<Map<String, dynamic>> incomes = [];
  List<Map<String, dynamic>> expenses = [];

   bool running = true;

  while (running) {
    print('\nMenu Options:');
    print('1. Add Income');
    print('2. Add Expense');
    print('3. View Summary');
    print('4. Exit');
    stdout.write('Choose an option (1-4): ');

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

     if (choice == null || choice < 1 || choice > 4) {
      print('Invalid choice. Please enter a number between 1 and 4.');
      continue;
    }

      // Use if/else for menu options
    if (choice == 1) {
      // Add Income
      stdout.write('Enter income description: ');
      String? description = stdin.readLineSync();
      if (description == null || description.trim().isEmpty) {
        print('Description cannot be empty.');
        continue;
      }
            stdout.write('Enter income amount: ');
      String? amountInput = stdin.readLineSync();
      double? amount = double.tryParse(amountInput ?? '');
      if (amount == null || amount <= 0) {
        print('Invalid amount. Please enter a positive number.');
      } else {
        incomes.add({'description': description, 'amount': amount});
        print('Income added successfully.');
      }
         } else if (choice == 2) {
      // Add Expense
      stdout.write('Enter expense description: ');
      String? description = stdin.readLineSync();
      if (description == null || description.trim().isEmpty) {
        print('Description cannot be empty.');
        continue;
      }
           stdout.write('Enter expense amount: ');
      String? amountInput = stdin.readLineSync();
      double? amount = double.tryParse(amountInput ?? '');
      if (amount == null || amount <= 0) {
        print('Invalid amount. Please enter a positive number.');
      } else {
               expenses.add({'description': description, 'amount': amount});
        print('Expense added successfully.');
      }
    } else if (choice == 3) {
      // View Summary
      double totalIncome = incomes.fold(0.0, (sum, item) => sum + item['amount']);
      double totalExpenses = expenses.fold(0.0, (sum, item) => sum + item['amount']);
      double net = totalIncome - totalExpenses;

     print('\nBudget Summary:');
      print('Total Income: \$${totalIncome.toStringAsFixed(2)}');
      print('Total Expenses: \$${totalExpenses.toStringAsFixed(2)}');

            if (net >= 0) {
        print('Net Profit: \$${net.toStringAsFixed(2)}');
        // Tax calculation using ternary operator
        double tax = (net > 0) ? net * 0.15 : 0.0;
        if (tax > 0) {
           print('Tax to be paid (15% of profit): \$${tax.toStringAsFixed(2)}');
        }
      } else {
        print('Net Loss: \$${(-net).toStringAsFixed(2)}');
      }

  // Optional: List details
      if (incomes.isNotEmpty) {
        print('\nIncome Details:');
        for (var income in incomes) {
          print('- ${income['description']}: \$${income['amount'].toStringAsFixed(2)}');
        }
      }
         if (expenses.isNotEmpty) {
        print('\nExpense Details:');
        for (var expense in expenses) {
          print('- ${expense['description']}: \$${expense['amount'].toStringAsFixed(2)}');
        }
      }
       } else if (choice == 4) {
      // Exit
      running = false;
      print('Exiting the Budget Management Application. Goodbye!');
    }
  }
}