Module finalization for Magento

Remote work for a web developer. The module created for Magento is still needed.
In this module, you need to implement api, which provides the possibility of increasing / decreasing the price of the product by a fixed value and by a certain percentage, depending on the transmitted parameters.
The result of executing the api command must be obtained by sending a curl request from a separate php file, in response to the request, the id of the modified product must return.
It is also necessary to log the changes that have occurred with the product.