Webbased Mockup generator in Java/Javascript

We are looking for a java or javascript based solution (Class or function) which will allow to replace a smart object layer with name "replaceme" in an existing PSD-Mockup file by a new given JPG or PNG file and save the result as new JPG file. The purpose of this project is to run in an java based online-shop environment which allows the visitor for example to upload an image which will then be mapped onto a mockup of eg. a mug. Therefore we need to be able to change the content of a given layer in an existing PSD-file which is a smart object and has transformations applied and then save the result as JPG file in order to present the result to the visitor. The replacement images will have the exact same size and resolution as the original content of the PSD-smart-object, so all image manipulations done inside Photoshop to the smart object will also apply to the new changed content as well. The mockups are rather simple and we currently only use Photoshop CS6 features and files. This can be done directly in Photoshop be right clicking the smart object and selecting "replace content" but in this project this functionality should be done by a Java or JavaScript function. So to be very specific: what we need for this is a Java Class or Java Script Function which allows to pass the path to an PSD file and another path to an image, both located on the server and the function will replace the layer „replaceme“ inside the given PSD file by the given image and return an JPG file of the final mockup. The system needs to run on an Linux based Apache Tomcat server without Photoshop installed (headless). We are open to suggestions and alternative solutions eg. based on Photon, etc.