import gradio as gr

def calculator(num1: float, num2: float, operation: str) -> str:
    """
    Perform basic arithmetic operations:
    - add: num1 + num2
    - subtract: num1 - num2
    - multiply: num1 * num2
    - divide: num1 / num2 (with zero-check)

    Args:
        num1: first number
        num2: second number
        operation: one of "add", "subtract", "multiply", "divide"

    Returns:
        The result as a float, or an error message string.
    """
    if operation == "add":
        return str(num1 + num2)
    elif operation == "subtract":
        return str(num1 - num2)
    elif operation == "multiply":
        return str(num1 * num2)
    elif operation == "divide":
        if num2 == 0:
            return "Error: Division by zero"
        return str(num1 / num2)
    else:
        return f"Error: Unknown operation '{operation}'"

demo = gr.Interface(
    fn=calculator,
    inputs=[
        gr.Number(value=0.0, label="First Number"),
        gr.Number(value=0.0, label="Second Number"),
        gr.Dropdown(["add", "subtract", "multiply", "divide"], label="Operation"),
    ],
    outputs=gr.Textbox(label="Result"),
    title="🧮 Simple Calculator",
    description="Enter two numbers and choose an operation."
)

if __name__ == "__main__":
    demo.launch(mcp_server=True)