// This program has been modified to be compatible with DartPad.
// 'dart:io' for synchronous console input/output is not supported in DartPad.
// To fix this, 'stdin.readLineSync()' has been replaced with a mock input
// mechanism, and 'stdout.write()' has been replaced with 'print()'.
// The program will now run through a predefined sequence of actions instead of
// requiring live user interaction.

// Mock input for DartPad compatibility.
// This list simulates user input for demonstration purposes.
List<String> mockInput = [
  "1", // Choose to Add Income
  "Salary", // Income description
  "2000", // Income amount
  "2", // Choose to Add Expense
  "Rent", // Expense description
  "800", // Expense amount
  "3", // Choose to View Summary
  "4", // Choose to Exit
];
int mockInputIndex = 0;

String? readMockInput() {
  if (mockInputIndex < mockInput.length) {
    // Optionally print the simulated input for clarity in the console
    print(" (Simulated input: '${mockInput[mockInputIndex]}')");
    return mockInput[mockInputIndex++];
  }
  // If we run out of mock input, return null to simulate end of input.
  return null;
}

void main() {
  // Lists to store income and expenses
  List<Map<String, double>> incomeList = [];
  List<Map<String, double>> expenseList = [];

  print("======== Welcome to Budget Manager ========");

  while (true) {
    print("\nMenu:");
    print("1. Add Income");
    print("2. Add Expense");
    print("3. View Summary");
    print("4. Exit");
    print("Enter your choice: "); // Replaced stdout.write with print
    String? choice = readMockInput(); // Replaced stdin.readLineSync()

    // ───────────────────────────────────────────────
    // 1. ADD INCOME
    // ───────────────────────────────────────────────
    if (choice == "1") {
      print("Enter income description: "); // Replaced stdout.write with print
      String? desc = readMockInput(); // Replaced stdin.readLineSync()

      print("Enter income amount: "); // Replaced stdout.write with print
      String? amtInput = readMockInput(); // Replaced stdin.readLineSync()
      double? amount = double.tryParse(amtInput ?? "");

      // Input validation
      if (amount == null || amount < 0) {
        print("❌ Invalid amount! Must be a positive number.");
      } else {
        incomeList.add({desc ?? "Unnamed Income": amount});
        print("✅ Income added successfully.");
      }
    }

    // ───────────────────────────────────────────────
    // 2. ADD EXPENSE
    // ───────────────────────────────────────────────
    else if (choice == "2") {
      print("Enter expense description: "); // Replaced stdout.write with print
      String? desc = readMockInput(); // Replaced stdin.readLineSync()

      print("Enter expense amount: "); // Replaced stdout.write with print
      String? amtInput = readMockInput(); // Replaced stdin.readLineSync()
      double? amount = double.tryParse(amtInput ?? "");

      // Input validation
      if (amount == null || amount < 0) {
        print("❌ Invalid amount! Must be a positive number.");
      } else {
        expenseList.add({desc ?? "Unnamed Expense": amount});
        print("✅ Expense added successfully.");
      }
    }

    // ───────────────────────────────────────────────
    // 3. VIEW SUMMARY
    // ───────────────────────────────────────────────
    else if (choice == "3") {
      double totalIncome = 0;
      double totalExpenses = 0;

      // Calculate totals
      for (var item in incomeList) {
        totalIncome += item.values.first;
      }
      for (var item in expenseList) {
        totalExpenses += item.values.first;
      }

      double net = totalIncome - totalExpenses;

      print("\n========== Budget Summary ==========");
      print("Total Income: \$${totalIncome.toStringAsFixed(2)}");
      print("Total Expenses: \$${totalExpenses.toStringAsFixed(2)}");

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

        // Optional Tax Feature (15% of profit)
        double tax = net * 0.15;
        print("💰 Tax to be paid (15%): \$${tax.toStringAsFixed(2)}");

      } else if (net < 0) {
        print("❌ Your net loss is \$${net.abs().toStringAsFixed(2)}");
      } else {
        print("Your budget is balanced. No profit, no loss.");
      }
    }

    // ───────────────────────────────────────────────
    // 4. EXIT
    // ───────────────────────────────────────────────
    else if (choice == "4") {
      print("Exiting Budget Manager... Goodbye!");
      return;
    }

    // ───────────────────────────────────────────────
    // INVALID CHOICE
    // ───────────────────────────────────────────────
    else {
      print("❌ Invalid choice. Please try again.");
    }
  }
}