Conversion from Goolge Map to Open Street Map with integration of MAPBOX api and leaflet.js required.

I want some modification in existing script. The existing script can load an image into google map at exact location using gps info in the image. I want to replace google map with open street map with [login to view URL] and MAPBOX api integration with the script. Add some functionalities of leaflet like add marker, measurement between two or more points, add annotation to the map and some drawing functions like draw a polygon, rectangle or circle on the map.