<?php
add_action( 'init', 'register_book_cpt' );

function register_book_cpt() {
    $labels = [
        'name'               => __( 'Books', 'textdomain' ),
        'singular_name'      => __( 'Book', 'textdomain' ),
        'add_new_item'       => __( 'Add New Book', 'textdomain' ),
        'edit_item'          => __( 'Edit Book', 'textdomain' ),
        'search_items'       => __( 'Search Books', 'textdomain' ),
        'not_found'          => __( 'No books found.', 'textdomain' ),
        'menu_name'          => __( 'Books', 'textdomain' ),
    ];

    register_post_type( 'book', [
        'labels'      => $labels,
        'public'      => true,
        'has_archive' => true,
        'rewrite'     => [ 'slug' => 'books' ],
        'supports'    => [ 'title', 'editor', 'thumbnail', 'excerpt', 'custom-fields' ],
        'show_in_rest' => true,
        'menu_icon'   => 'dashicons-book',
    ] );

    register_taxonomy( 'genre', 'book', [
        'labels'       => [ 'name' => __( 'Genres', 'textdomain' ) ],
        'hierarchical' => true,
        'show_in_rest' => true,
        'rewrite'      => [ 'slug' => 'genre' ],
    ] );
}