REFACTORING PHP code

There is a project: a small web site, back in php, data in mariadb. The archive with the project is attached to the application. The project is raised by the command to run the run script, so that this script works correctly, you need to work out the docker compose command (through a space), if such a command does not work, then you need to update docker to the latest version.

The task itself: you need to refactor the file ./panel/www/svc/team/layout/chat/api.php

Refactoring refers to the following tasks:
- API calls, parameters, names – hard-coded
- Multiple code duplication
- Error handling at random
- Poorly demarcated names/entities
- Too many global variables
- poor upload/download processing

This task is part of a large project for a couple of years. We are looking for a specialist with high qualifications, which will need to be confirmed, and for long-term cooperation. Refactoring is paid at a price of 2000 rubles per hour. According to this task, we evaluate the qualifications. If the qualification suits us, then further tasks from 4000 rubles per hour. Intermediaries are not needed, I am interested in contact with the direct executor.