Combining OSMbuildings for 3D buildings and indoor mapping?

Hi,I am a beginner and in need for some help. I want to implement a map in my web app where I have:-

  1. 3D buildings using osmbuildings
  2. After a particular action is taken(a certain zoom level,button click or click on a building) an Indoor mapping plan which I have already implemented using JOSM is shown. I only have .osm file right now.

If there is a better way to implement 3D buildings or what I need in particular is possible then please do let me know. Also if there is a way How can I use my custom built .osm file to be shown in my web app something like openlevelup. Will appreciate any help. Thanks!