//搜索结果页面关键字高亮
function fanly_highlight_search_keywords($text){
    if ( is_search() ) {
        $s = get_search_query();
        $keys = explode(' ', $s);
        $text = preg_replace('/(' . implode('|', $keys) . ')/iu', '<strong class="highlight">$1</strong>', $text);
    }
    return $text;
}
add_filter( 'the_title', 'fanly_highlight_search_keywords' );
add_filter( 'the_excerpt', 'fanly_highlight_search_keywords' );

//搜索关键字为空时自动跳转到首页
function fanly_redirect_blank_search( $query_variables ) {
    if ( isset( $_GET['s'] ) && empty( $_GET['s']) ) {
        wp_redirect( home_url() );
        exit;
    }
    return $query_variables;
}
add_filter( 'request', 'fanly_redirect_blank_search' );

//关闭文章的标签功能
function fanly_unregister_post_tag() {
    unregister_taxonomy_for_object_type('post_tag', 'post');
}
add_action( 'init', 'fanly_unregister_post_tag' );

//清理 WordPress 菜单中的 classes
function fanly_cleanup_nav_menu_class( $classes ) {
    return array_intersect($classes, array(
        'current-menu-item',
        'menu-item-has-children'
    ));
}
add_filter( 'nav_menu_css_class', 'fanly_cleanup_nav_menu_class' );

//自动设置文章的第一张图为特色图像
function fanly_autoset_featured_image() {
    global $post;
    if (!is_object($post)) return;
    $already_has_thumb = has_post_thumbnail($post->ID);
    if (!$already_has_thumb)  {
        $attached_image = get_children( "post_parent=$post->ID&post_type=attachment&post_mime_type=image&numberposts=1" );
        if ($attached_image) {
            foreach ($attached_image as $attachment_id => $attachment) {
                set_post_thumbnail($post->ID, $attachment_id);
            }
        }
    }
}
add_action( 'the_post', 'fanly_autoset_featured_image' );
add_action( 'save_post', 'fanly_autoset_featured_image' );
add_action( 'draft_to_publish', 'fanly_autoset_featured_image' );
add_action( 'new_to_publish', 'fanly_autoset_featured_image' );
add_action( 'pending_to_publish', 'fanly_autoset_featured_image' );
add_action( 'future_to_publish', 'fanly_autoset_featured_image' );