I want to get start and end position of selection in tinymce editor and want to insert custom tags there.

E.g.
If in editor we have below text,

This is <a>google</a> help line. We may help in problem.

And if user selects
“google help line. We may”

Then we can add any custom tag and start and end of it.

Solution should work with any html tag in between selection without impacting existing html