Rotating camera using gamepad (3D)

Question

Hi, i have code, that rotating camera when i move mouse :

func input(event):
if canRotateCam:
if event is InputEventMouseMotion:
roty -= event.relative.x * sens
rotx -= event.relative.y * sens
if rotx < -1: rotx = -1
if rotx > 1: rotx = 1
transform.basis = Basis(Vector3(0, 1, 0), roty)
$Head.transform.basis = Basis(Vector3(1, 0, 0), rot_x)

how to create rotation camera like this, but using gamepad? Thanks in advice