AppleScript in OS X 10.10 to Resize Safari window and take Screen Shot of that window and repeat with multiple sizes

I would like to build an AppleScript Application that when run will do the following:

1. 
   

   Open up Safari and navigate to a specific URL, or a line delimited file, or CSV. This is not required but would make generating multiple screenshots of different pages a lot quicker.

   
   


2. 
   

   Resize the Safari window to one of a number of sizes

   
   


3. 
   

   Take a screenshot of the Safari window with the filename being the url along with the screen size