import 'dart:io';

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

  bool running = true;

  print("=== Budget Management Application ===");

  while (running) {
    print("");
    print("Please choose an option:");
    print("1. Add income");
    print("2. Add expense");
    print("3. View summary (net profit/loss)");
    print("4. Exit");
    stdout.write("Your choice: ");

    String? choice = stdin.readLineSync();

    if (choice == '1') {
      addIncome(incomeList);
    } else if (choice == '2') {
      addExpense(expenseList);
    } else if (choice == '3') {
      viewSummary(incomeList, expenseList);
    } else if (choice == '4') {
      print("Exiting the application. Goodbye!");
      running = false;
    } else {
      print("Invalid choice. Please try again.");
    }
  }
}

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

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

  if (description == null || description.isEmpty) {
    print("Description cannot be empty.");
    return;
  }

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

  incomeList.add({description: amount});
  print("Income added: $description - \$${amount.toStringAsFixed(2)}");
}

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

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

  if (description == null || description.isEmpty) {
    print("Description cannot be empty.");
    return;
  }

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

  expenseList.add({description: amount});
  print("Expense added: $description - \$${amount.toStringAsFixed(2)}");
}

void viewSummary(
    List<Map<String, double>> incomeList, List<Map<String, double>> expenseList) {
  print("");
  print("=== Budget Summary ===");

  double totalIncome = 0;
  for (var entry in incomeList) {
    totalIncome += entry.values.first;
  }

  double totalExpenses = 0;
  for (var entry in expenseList) {
    totalExpenses += entry.values.first;
  }

  double net = totalIncome - totalExpenses;

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

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

    // Tax calculation using ternary operator (15% only if profit)
    double tax = net > 0 ? net * 0.15 : 0.0;
    print("Tax to be paid (15% of profit): \$${tax.toStringAsFixed(2)}");
  } else if (net < 0) {
    double loss = -net;
    print("Your net loss is \$${loss.toStringAsFixed(2)}");
    print("No tax is calculated because there is a loss.");
  } else {
    print("You are breaking even. No profit, no loss.");
    print("No tax is calculated.");
  }
}