Allow authors to post only in categories they create in WordPress

This little plugin shows the user role ‘author’ only its own categories & posts. So you can edit it for your own post-type and taxonomy.

/*
Plugin Name: Show own categories
Description: This plugin shows the user role 'author' only its own categories & posts
Version:     0.1
Author:      Soren Wrede
License:     GPL2
License URI: https://www.gnu.org/licenses/gpl-2.0.html
*/

class SW_Category_Restriction{
    private $user_cats = NULL;

    public function __construct(){
        //Save author ID for category
        add_action( 'create_category', array( &$this, 'save_category_author' ) );
        //Set manage_categories cap for 'Author'
        add_action( 'admin_init', array( &$this, 'add_author_cap_categories' ) );
        //Remove manage_categories  capfor 'Author'
        register_deactivation_hook( __FILE__, array( &$this, 'remove_author_cap_categories' ) );
        //Filter categorys in new-post, edit-post, edit-categories
        add_action( 'admin_print_scripts-post-new.php', array( &$this, 'filter_post_page' ) );
        add_action( 'admin_print_scripts-post.php', array( &$this, 'filter_post_page' ) );
        add_action( 'admin_print_scripts-edit-tags.php', array( &$this, 'filter_post_page' ) );
        //just show own posts
        global $pagenow;
        if ( $pagenow == 'edit.php' )
            add_filter( 'pre_get_posts', array( &$this, 'filter_edit_page' ) );
    }

    public function save_category_author( $term_id ) {
        $user_id = get_current_user_id();
        add_term_meta( $term_id, 'author', $user_id );
    }

    public function get_user_cats( $user_id ) {
        $args = [
            'hide_empty' => false,
            'meta_query' => [
                [
                    'key' => 'author',
                    'value' => $user_id,
                ]
            ]
        ];
        $terms = get_terms( 'category', $args );
        $ids="-1,";
        foreach ($terms as $term ) {
            $ids .= $term->term_id . ',';
        }
        $ids = substr($ids, 0, -1);
        $this->user_cats = $ids;
    }

    public function add_author_cap_categories() {
        $role = get_role( 'author' );
        $role->add_cap( 'manage_categories' );
    }

    public function remove_author_cap_categories() {
        $role = get_role( 'author' );
        $role->remove_cap( 'manage_categories' );
    }

    public function exclusions( $exclusions ){
        $exclusions .= " AND ( t.term_id IN ( $this->user_cats ) OR tt.taxonomy NOT IN ( 'category' ) )";
        return $exclusions;
    }

    public function filter_post_page() {
        //check post-type 
        $screen = get_current_screen();
        if ( $screen->post_type != 'post' )
            return;

        //just Author and lower
        if ( current_user_can('delete_others_posts') )
            return;

        $user_id = get_current_user_id();
        $this->get_user_cats( $user_id );

        if ( empty( $this->user_cats ) )
            return;

        add_filter( 'list_terms_exclusions', array( &$this, 'exclusions' ) );
    }

    public function filter_edit_page( $query ) {
        if ( current_user_can('delete_others_posts') )
            return;     
        $query->set( 'author', get_current_user_id() );

        return $query;
    }

}

new SW_Category_Restriction();