Simulate mouse movement in Ubuntu

Problem

Am looking to automatically move the mouse cursor and simulate mouse button clicks from the command-line using an external script. Am not looking to:

• Record mouse movement and playback (e.g., xnee, xmacro)
• Instantly move the mouse from one location to another (e.g., xdotool, Python's warp_pointer)

Ideal Solution

What I'd like to do is the following:

1. Edit a simple script file (e.g., mouse-script.txt).
2. Add a list of coordinates, movement speeds, delays, and button clicks. For example:

   (x, y, rate) = (500, 500, 50)sleep = 5click = left

3. Run the script: xsim < mouse-script.txt.

Question

How do you automate mouse movement so that it transitions from its current location to another spot on the screen, at a specific velocity? For example:

xdotool mousemove 500 500 --rate 50

The --rate 50 doesn't exist with xdotool.