SEO Title, Description and Noindex Fields

$wpide_seo_types = function () {
    return array_values( array_diff( get_post_types( array( 'public' => true ) ), array( 'attachment' ) ) );
};

add_action( 'add_meta_boxes', function () use ( $wpide_seo_types ) {
    add_meta_box( 'wpide-seo', 'SEO', function ( $post ) {
        wp_nonce_field( 'wpide_seo_save', 'wpide_seo_nonce' );
        $title       = get_post_meta( $post->ID, '_wpide_seo_title', true );
        $description = get_post_meta( $post->ID, '_wpide_seo_description', true );
        $noindex     = get_post_meta( $post->ID, '_wpide_seo_noindex', true );
        echo '<p><label for="wpide-seo-title"><strong>Title</strong></label><br /><input type="text" class="widefat" id="wpide-seo-title" name="wpide_seo_title" value="' . esc_attr( $title ) . '" maxlength="120" /></p>';
        echo '<p><label for="wpide-seo-description"><strong>Meta description</strong></label><br /><textarea class="widefat" rows="3" id="wpide-seo-description" name="wpide_seo_description" maxlength="320">' . esc_textarea( $description ) . '</textarea><span class="description">About 150 characters works best.</span></p>';
        echo '<p><label><input type="checkbox" name="wpide_seo_noindex" value="1"' . checked( $noindex, '1', false ) . ' /> Hide from search engines (noindex)</label></p>';
    }, $wpide_seo_types(), 'normal', 'low' );
} );

add_action( 'save_post', function ( $post_id ) {
    if ( ! isset( $_POST['wpide_seo_nonce'] ) || ! wp_verify_nonce( sanitize_text_field( wp_unslash( $_POST['wpide_seo_nonce'] ) ), 'wpide_seo_save' ) ) {
        return;
    }

    if ( ( defined( 'DOING_AUTOSAVE' ) && DOING_AUTOSAVE ) || wp_is_post_revision( $post_id ) || ! current_user_can( 'edit_post', $post_id ) ) {
        return;
    }

    $fields = array(
        '_wpide_seo_title'       => isset( $_POST['wpide_seo_title'] ) ? sanitize_text_field( wp_unslash( $_POST['wpide_seo_title'] ) ) : '',
        '_wpide_seo_description' => isset( $_POST['wpide_seo_description'] ) ? sanitize_textarea_field( wp_unslash( $_POST['wpide_seo_description'] ) ) : '',
        '_wpide_seo_noindex'     => empty( $_POST['wpide_seo_noindex'] ) ? '' : '1',
    );

    foreach ( $fields as $key => $value ) {
        if ( '' === $value ) {
            delete_post_meta( $post_id, $key );
        } else {
            update_post_meta( $post_id, $key, $value );
        }
    }
} );

add_filter( 'pre_get_document_title', function ( $title ) {
    if ( is_singular() ) {
        $custom = get_post_meta( get_queried_object_id(), '_wpide_seo_title', true );

        if ( '' !== $custom ) {
            return $custom;
        }
    }

    return $title;
}, 20 );

add_action( 'wp_head', function () {
    if ( ! is_singular() ) {
        return;
    }

    $description = get_post_meta( get_queried_object_id(), '_wpide_seo_description', true );

    if ( '' !== $description ) {
        echo '<meta name="description" content="' . esc_attr( $description ) . '" />' . "\n";
    }
}, 1 );

add_filter( 'wp_robots', function ( $robots ) {
    if ( is_singular() && get_post_meta( get_queried_object_id(), '_wpide_seo_noindex', true ) ) {
        $robots['noindex'] = true;
        $robots['follow']  = true;
    }

    return $robots;
} );

add_filter( 'wp_sitemaps_posts_query_args', function ( $args ) {
    $args['meta_query'] = array(
        array(
            'key'     => '_wpide_seo_noindex',
            'compare' => 'NOT EXISTS',
        ),
    );

    return $args;
} );