import 'dart:io';

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

  while (true) {
    print("\n========= Income & Expense Manager =========");
    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':
        addTransaction(incomeList, "Income");
        break;

      case '2':
        addTransaction(expenseList, "Expense");
        break;

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

      case '4':
        print("👋 Exiting system... Goodbye!");
        return;

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

void addTransaction(List<Map<String, dynamic>> list, String type) {
  stdout.write("📌 Enter $type description: ");
  String? desc = stdin.readLineSync();
  stdout.write("💰 Enter amount: ");
  double? amount = double.tryParse(stdin.readLineSync() ?? '');

  if (amount == null || amount < 0) {
    print("❌ Invalid amount!");
    return;
  }

  list.add({
    'description': desc ?? 'No description',
    'amount': amount,
  });
  print("✅ $type added successfully!");
}

void showSummary(List<Map<String, dynamic>> incomes, List<Map<String, dynamic>> expenses) {
  double totalIncome = incomes.fold(0, (sum, e) => sum + e['amount']);
  double totalExpenses = expenses.fold(0, (sum, e) => sum + e['amount']);
  double net = totalIncome - totalExpenses;

  print("\n========= 💼 Financial Summary =========");
  print("📈 Total Income: \$${totalIncome.toStringAsFixed(2)}");
  print("📉 Total Expenses: \$${totalExpenses.toStringAsFixed(2)}");
  print("💰 Net Balance: \$${net.toStringAsFixed(2)}");

  if (net > 0) {
    double tax = net * 0.15;
    print("💸 Tax (15%): \$${tax.toStringAsFixed(2)}");
  } else if (net < 0) {
    print("🔴 You are in deficit!");
  } else {
    print("⚖️ Balanced budget — no profit or loss.");
  }
}