search-tag wordpress christianto wpquestions.com

$SEARCH_TAG__RUN = false;

function post_tagsort($a, $b) {
    return (count($a) - count($b));
};
function tag_search_query($query) {

    global $wpdb, $SEARCH_TAG__RUN;
    if ( is_tag() && !$SEARCH_TAG__RUN){

        $taxquery = $sort_posts = $search_tags = $tags_connection = $myposts_id = array();

        $search_tags = explode('+',$query->query_vars['tag']);
        $taxquery['operator'] = 'AND';
        foreach ($search_tags as $term){
            $taxquery[] = array(
                'taxonomy'  =>  'post_tag',
                'field'     =>  'slug',
                'terms'     =>  $term
            );
        }

        $raw_alltags = $wpdb->get_results( "SELECT term_id FROM $wpdb->term_taxonomy WHERE taxonomy = 'post_tag'", ARRAY_A);
        foreach($raw_alltags as $tag){
            $alltags[] = $tag['term_id'];
        }

        $SEARCH_TAG__RUN = true;
        $args = array(  'post_type' => 'post', 'posts_per_page' => -1, 'tax_query' => $taxquery );
        $tagposts = get_posts( $args );
        foreach($tagposts as $post){
            $myposts_id[] = $post->ID;
        }

        $tags_connection = array();
        $alltags_connection = $wpdb->get_results( "SELECT object_id, term_taxonomy_id FROM $wpdb->term_relationships", ARRAY_A);
        foreach($alltags_connection as $tag){
            if(in_array($tag['object_id'], $myposts_id) && in_array($tag['term_taxonomy_id'], $alltags)){
                if($tags_connection[$tag['object_id']]['post_id'] != $tag['object_id'])
                    $tags_connection[$tag['object_id']]['post_id'] = $tag['object_id'];
                $tags_connection[$tag['object_id']][] = $tag['term_taxonomy_id'];
            }
        }

        usort($tags_connection, 'post_tagsort');

        foreach($tags_connection as $t){
            $sort_posts[] = $t['post_id'];
        }

        $SEARCH_TAG__RUN = false;
        $query->set( 'post__in', $sort_posts );
        $query->set( 'orderby', 'post__in' );
    }

    return $query;
}
add_filter( 'pre_get_posts', 'tag_search_query' );