There is no 100% way to do this.
You can split on spaces, and try to understand the name all you want, but when it comes down to it, you will get it wrong sometimes. If that is good enough, go for any of the answers here that give you ways to split.
But some people will have a name like "John Wayne Olson", where "John Wayne" is the first name, and someone else will have a name like "John Wayne Olson" where "Wayne" is their middle name. There is nothing present in that name that will tell you which way to interpret it.
That's just the way it is. It's an analogue world.
My rules are pretty simple.
Take the last part --> Last Name
If there are multiple parts left, take the last part --> Middle name
What is left --> First name
But don't assume this will be 100% accurate, nor will any other hardcoded solution. You will need to have the ability to let the user edit this him/her-self.
