Student Loan Calculator

def calculate_student_loan(principal: float, annual_rate: float,
                             years: int) -> dict:
    """Calculate student loan monthly payment and total interest."""
    monthly_rate = annual_rate / 100 / 12
    n = years * 12

    if monthly_rate == 0:
        monthly_payment = principal / n
    else:
        monthly_payment = principal * (monthly_rate * (1 + monthly_rate) ** n) /                           ((1 + monthly_rate) ** n - 1)

    total_payment = monthly_payment * n
    total_interest = total_payment - principal

    return {
        "monthly_payment": round(monthly_payment, 2),
        "total_payment": round(total_payment, 2),
        "total_interest": round(total_interest, 2),
    }

def amortization_schedule(principal: float, annual_rate: float, years: int):
    """Generate full amortization schedule."""
    monthly_rate = annual_rate / 100 / 12
    n = years * 12
    payment = calculate_student_loan(principal, annual_rate, years)["monthly_payment"]
    balance = principal
    for month in range(1, n + 1):
        interest = balance * monthly_rate
        principal_part = payment - interest
        balance -= principal_part
        yield {
            "month": month,
            "payment": round(payment, 2),
            "principal": round(principal_part, 2),
            "interest": round(interest, 2),
            "balance": round(max(balance, 0), 2),
        }

# Example: $30,000 loan at 5.5% over 10 years
result = calculate_student_loan(30000, 5.5, 10)
print(f"Monthly Payment: ${result['monthly_payment']}")
print(f"Total Payment: ${result['total_payment']}")
print(f"Total Interest: ${result['total_interest']}")