Php script - Extract product and category information from prestashop webservices

I need a php script that is able to extract all products with categories, url, image link, description and any other product relation specifications from Prestashop through the webservices available. It should be able to do so for at least the last 3 main versions of Prestashop (1.5, 1.6, 1.7) The result should be that if supplied two url parameters that contains the shop url and the webservice key it should first test if it has access to the webservices, if not write that to the screen. If it has accecss, it should then iterate over every product and display them in the browser. The php has to be wellstructured - of huge importance. So no one long function, either use classes or a set of functions to complete it.