Error Handling and Refinement

income = 0.0
expenses = [] # Each item is a dict: {"category": str, "amount": float}

# Common categories to suggest to the user
allowed_categories = [
    "Food", "Rent", "Transport", "Entertainment",
    "Utilities", "Health", "Education", "Other"
]

def add_income(amount):
    """Set or update the monthly income (float > 0)."""
    global income
    income = float(amount)

def add_expense(category, amount):
    """Append an expense entry with category, amount (>0)."""
    new_expense = {
        "category": category,
        "amount": float(amount)
    }
    expenses.append(new_expense)

def delete_expense(idx):
    """Delete an expense by zero-based"""
    return expenses.pop(idx)

def total_spent(expenses_list=None):
    """Return the sum of all expense amounts from a list or the global store."""
    if expenses_list is None:
        expenses_list = expenses
    return sum(entry["amount"] for entry in expenses_list)

def compute_category_totals(expenses_list=None):
    """Return a dict mapping category -> total amount from expenses."""
    if expenses_list is None:
        expenses_list = expenses
    
    totals = {}
    for entry in expenses_list:
        category = entry["category"]
        amount = entry["amount"]
        totals[category] = totals.get(category, 0) + amount
    return totals

def print_report(income_value=None, expenses_list=None):
    """Print a formatted budget report with category totals and status line."""
    if income_value is None:
        income_value = income
    if expenses_list is None:
        expenses_list = expenses

    total = total_spent(expenses_list)
    remaining_balance = income_value - total
    category_totals = compute_category_totals(expenses_list)
    
    print("\n--- Budget Report ---")
    print(f"Income: ${income_value:.2f}")
    print(f"Total Spent: ${total:.2f}")
    
    print("\nCategory Spending:")
    for category, amount in category_totals.items():
        print(f"  - {category}: ${amount:.2f}")
    
    print("-" * 27)
    print(f"Remaining Balance: ${remaining_balance:.2f}")
    
def show_menu():
    """Display simple command menu for the CLI."""
    print("\n--- Budget Tracker Menu ---")
    print("1. Set Monthly Income")
    print("2. Add an Expense")
    print("3. Delete an Expense")
    print("4. Show Budget Report")
    print("5. Reset All Data")
    print("6. Exit")

# Helper function to list expenses
def list_expenses():
    """Display all expenses with their index."""
    if not expenses:
        print("No expenses recorded yet.")
        return
    print("\nCurrent Expenses:")
    for i, expense in enumerate(expenses):
        print(f"{i}: {expense['category']} - ${expense['amount']:.2f}")
        
def reset_data():
    """Clear income and expenses; return to a clean initial state."""
    global income, expenses
    income = 0.0
    expenses.clear()
    print("All budget data has been cleared.")

def run_cli():
    """Main loop: set income, add expenses, show report/export, reset, exit."""
    global income
    print("Welcome to Budget Tracker!")
    income_input = input("Enter your monthly income: ")
    add_income(income_input)

    while True:
        show_menu()
        choice = input("Choose an option: ").strip()

        if choice == "1":
            amount = input("Enter new monthly income: ")
            add_income(amount)
        elif choice == "2":
            # Display categories to the user
            print("\nAvailable Categories:")
            for i, cat in enumerate(allowed_categories):
                print(f"{i}: {cat}")
            
            # Prompt for category and amount
            category_idx_str = input("Enter the number for the category: ")
            category_idx = int(category_idx_str)

            if 0 <= category_idx < len(allowed_categories):
                category = allowed_categories[category_idx]
                amount = input(f"Enter expense amount for {category}: ")
                add_expense(category, amount)
                print("Expense added.")
            else:
                print("Invalid category number. Please try again.")

        elif choice == "3":
            list_expenses()  # Display list before prompting for deletion
            if not expenses:
                continue
            
            idx_str = input("Enter the index of the expense to delete: ")
            idx = int(idx_str)
            
            if 0 <= idx < len(expenses):
                deleted_expense = delete_expense(idx)
                print(f"Deleted expense: {deleted_expense['category']} - ${deleted_expense['amount']:.2f}")
            else:
                print("Invalid index. No expense deleted.")
        elif choice == "4":
            print_report()
        elif choice == "5":
            reset_data()
        elif choice == "6":
            print("Goodbye!")
            break
        else:
            print("Invalid choice. Please try again.")

if __name__ == "__main__":
    run_cli()