How to make Intellij highlight and collapse code (in your own language)?

Question

I'm making my own programming language. But now I want Intellij to highlight my new language and also - and that is very important for me - to collapse code blocks. What I mean by that is the following. Consider this example code:

if(1==1) {
    foo1();
    foo2();
}

in Intellij you can click on the side like in this picture here
in line 30 and 33. And of course when you press them the code collapses to something like

if(1==1) {...}

so how to make Intellij do that with my new programming language?

Also any ideas how to make Intellij give me hints in a drop down menu, what my input might be and insert them when I press enter? something like that here:

Thank you for your help. Also partial answers or even small hints are warmly welcomed :)