import 'dart:io';

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

  print("=======================================");
  print(" Welcome to the Budget Management App ");
  print("=======================================\n");

  bool isRunning = true;

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

    stdout.write("Enter your choice: ");
    String? choice = stdin.readLineSync();

    switch (choice) {
      case '1':
        addIncome(incomeList);
        break;

      case '2':
        addExpense(expenseList);
        break;

      case '3':
        viewSummary(incomeList, expenseList);
        break;

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

      default:
        print("Invalid choice. Please try again.");
    }
  }
}

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

  stdout.write("Enter income amount: ");
  double? amount = double.tryParse(stdin.readLineSync() ?? '');

  if (amount == null || amount <= 0) {
    print("Invalid amount. Please enter a positive number.");
    return;
  }

  incomeList.add({description ?? "Unknown": amount});
  print("Income added successfully!");
}

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

  stdout.write("Enter expense amount: ");
  double? amount = double.tryParse(stdin.readLineSync() ?? '');

  if (amount == null || amount <= 0) {
    print("Invalid amount. Please enter a positive number.");
    return;
  }

  expenseList.add({description ?? "Unknown": amount});
  print("Expense added successfully!");
}

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

  for (var income in incomeList) {
    totalIncome += income.values.first;
  }

  for (var expense in expenseList) {
    totalExpenses += expense.values.first;
  }

  double net = totalIncome - totalExpenses;

  print("\n========== Summary ==========");
  print("Total income: \$${totalIncome.toStringAsFixed(2)}");
  print("Total expenses: \$${totalExpenses.toStringAsFixed(2)}");

  if (net > 0) {
    print("Net profit: \$${net.toStringAsFixed(2)}");

    double tax = net * 0.15;
    print("Tax to be paid (15%): \$${tax.toStringAsFixed(2)}");
  } else if (net < 0) {
    print("Net loss: \$${net.abs().toStringAsFixed(2)}");
    print("No tax applied (business is at a loss).");
  } else {
    print("Break-even: No profit, no loss.");
  }

  print("=============================\n");
}