JSF dynamic query args prototype

base-arg.php

<?php
// Base arg class. all args must extend it
abstract class Base_Arg {
	
	// returns main arg
	abstract public function get_arg();
	
	// returns main arg label for UI control
	abstract public function get_name();
	
	// return additional arguments if needed
	public function get_extra_args() {
		return [];
	}
	
	// return main and additiona arguments delimiter if needed
	public function get_delimiter() {
		return ''
	}
}

dynamic-args-manager.php

<?php
// manager class, contain data about all args to pass it into JS component
class Args_Manager {
	
	private $_args = [];
	
	public function __construct() {
		add_action( 'init', array( $this, 'register_args' ) );
	}
	
	public function register_args() {
		require 'base-arg.php';
		do_action( 'prefix/register-dynamic-arg', $this );
	}
	
	public function register_arg( $arg_instance ) {
		$this->_args[ $arg_instance->get_arg() ] = $arg_instance;
	}
	
}

my-arg.php

<?php
// Class demonstrates example of custom query argument with additional data
class My_Arg extends Base_Arg {

	public function get_arg() {
        return 'related_children';
    }

	public function get_name() {
		return 'Filter by related children';
	}
    
    public function get_extra_args() {
        return [
            'rel_id' => [
                'label' => 'Select Relation',
                'description' => 'select relation to filter by children items from',
                'type' => 'select', // allowed types - text and select
                'options' => [
                    [
                        'value' => 1,
                        'label' => 'rel 1',
                    ],
                     [
                        'value' => 2,
                        'label' => 'rel 2',
                    ],
                ],
            ],
        ];
    }
    
    public function get_delimiter() {
		return '*'
	}
}

register-custom-arg.php

<?php
// Class demonstrates logic of registering custom arg
class Register_My_Arg {
	public function __construct() {
		// hook from dynamic-args-manager.php
		add_action( 'prefix/register-dynamic-arg', array( $this, 'register_arg' ) );
	}
  
	public function register_arg( $manager ) {
		require 'my-arg.php';
		$manager->register_arg( new My_Arg() );
	}
}