import 'dart:io';

void main() {
  print("Welcome to the budget management Application!\n");
  List<Map<String, double>> incomelist = [];
  List<Map<String, double>> expenselist = [];

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

    print("Enter your choice:\n");

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

    if (choice == null) {
      print("invalid input:\nPlease enter a number 1-4.\n");
      continue;
    }
    switch (choice) {
      case 1:
        print("Enter income description: .");
        String? description = stdin.readLineSync();
        description = (description == null || description.trim().isEmpty)
            ? " income"
            : description.trim();
        print("Enter income amount:");
        String? amounttext = stdin.readLineSync();
        double? amount = double.tryParse(amounttext ?? '');
        if (amount == null || amount < 0) {
          print("invalid amount. please enter a positive number.");
        } else {
          incomelist.add({description: amount});
          print("income added! \n");
        }
        break;

      case 2:
        print("Enter expense dascription.");
        String? dascription1 = stdin.readLineSync();
        dascription1 = (dascription1 == null || dascription1.trim().isEmpty)
            ? "Expense"
            : dascription1.trim();
        print("Enter expense amount.");
        String? amounttext = stdin.readLineSync();
        double? amount1 = double.tryParse(amounttext ?? '');
        if (amount1 == null || amount1 < 0) {
          print("invalid amount.please enter a positive number.");
        } else {
          expenselist.add({dascription1: amount1});
          print("Expense added! \n");
        }

        break;

      case 3:
        print("summary.\n");
        double total_income = 0;
        for (var item in incomelist) {
          total_income += item.values.first;
        }
        double total_expeses = 0;
        for (var item in expenselist) {
          total_expeses += item.values.first;
        }
        double net = total_income - total_expeses;
        double tax = net > 0 ? net * 0.15 : 0;
        print("total income: \$${total_income}");
        print("total expenses: \$${total_expeses}");
        if (net >= 0) {
          print("net profit. \$${net}");
          print("tax to be paid. \$${tax}");
        } else {
          print("net loss. \$${-net}");
          print("tax to be paid. \$0");
        }
        break;

      case 4:
        print("\nExiting the application. Googbye!\n");
        task = false;
        break;

      default:
        print("Please enter a number 1-4.\n");
    }
  }
}