Hi,
im norhan node.js backend developer, I read the pdf file and i can make the required task with high quality and robustness
first I can validate the contents of the file and return an error if it contains, and convert any file type to pdf
I can deal with files according to its meme type
then make a thumbnails as required
and at last store the original and the pdf document into the server
don't hesitate to contact me :)