FFMPEG command to add text watermark in dynamic position on a video

I need ffmpeg command that does the following. It places text on an input video for example Watermark and moves the text as it is shown in the attached HTML/Javascript page. Initial Position: The watermark randomly placed in the video the first time they appear. Continuous Movement: The watermark continuously moves within the video. The direction and speed of the watermark's movement are random. It can move diagonally, purely horizontally, or purely vertically. When the watermark reaches the boundaries of the video, it bounces back, changing its direction. Direction Change: During its continuous movement, the watermark will suddenly change its direction at random intervals between 3 to 6 seconds. When changing direction, the watermark can randomly determined move diagonally, purely horizontally, or purely vertically. Fade In and Out: Every 10 to 20 seconds (randomly determined), the current watermark begins to fade out. As the old watermark starts to fade out, a new watermark fades in at a random position, ensuring that there's always a visible watermark on the screen. These two watermarks (the fading old one and the emerging new one) overlap on the screen for a duration of 2 seconds, after which the old watermark completely disappears. These patterns and characteristics together provide a dynamic, constantly moving, and changing watermark for the video. Attached HTML file shows similar animation but I need it done using ffmpeg command.