Make an API in php under Yandex.Market for digital goods

Make an API in php for automatic processing, acceptance and delivery of orders with digital codes. Also make an api to check for the availability of goods. Keys to each product will be located in txt files (each product has its own txt file, the name of the txt file is the SKU of the product). After sending the key, the corresponding line in the txt file is deleted. Check the presence to take from the list of remaining lines of the txt file of the corresponding product (check txt files for the number of remaining lines once an hour). The entire API will be located on a purely technical empty site. When you are finished, install the api on the site.