We need to write a web service where we will get username of user. We would like to give endpoints to get,create,update and delete files(SPItem) from document library for user. We have admin credentials stored in our web.config(or somewhere else). We don't want to ask user his password as we are authenticating user with different methods(which is not domain/AD). Also, we want to make sure, user will be able to all of these actions only if he have permission to related items. Like we want to return list of files/folders from document library but only those to which user have permission.
So, how do we perform these action for user and should look like user have done these action in sharepoint site.
Thanks,