Question about bottom of pool - resurface or not?

[albertmurr89]

Looking to purchase a home, however unsure what these round inground "cleaners" are, i cant find anything on google images on the web. Who knows when the pool was built, it still has a diving board.

A few questions:

What are the names of these and are they obsolete
What do you think an average estimate will go for to fix this?
Does the pool need to be resurfaced completely or can it be done it an afordable rate by patching the cracks?
Thank you

Link to image: [DELETED ]

[PoolDoc]

Image link was to a malware (virus, etc) associated image hosting site. (ibb DOT co)

I have no way to know whether this was deliberate or accidental; asking won't help, since even if it WAS deliberate, the person is virtually certain to claim it was an accident.