sort netsted record in wp

gistfile1.txt

//referral post type
//iranam plugin

function sort_referral($mains, $user_id)
	{
	    $result = [];
	    foreach( $mains as $key=>$main )
	    {
	        $data = $main;
	        if( (int)$main->post_author == $user_id )
	        {
	            $email = $main->post_content;
	            
	            $user = get_user_by( 'email', $email );
	            $id = $user->ID;
	            
	            $mains[$key]->child = $this->sort_referral($mains, $id);
	            $result[] = $main;
	        } 
	    }
	    
	    return $result;
	}