<?php

class Taxonomy {

        /**   
         * Register taxonomy metadata
         *
         * We use the taxonomy metadata for color info right now and later for
         * subscription status etc. Run this code after the taxonomy 'taxonomy'
	 * has been registered.
         *
	 * @fixme The code to create the table should only run once
	 * @todo the switch_blog action has always to be hooked into
	 *
         * @return none
         */
        function add_taxonomy_meta() {
                $this->create_taxonomy_meta_table();
                $this->update_wpdb();
                add_action( 'switch_blog', array( &$this, 'update_wpdb' ) );
        }     

        /**   
         * WordPress doesn't seem to support metadata on custom taxonomies out
         * of the box, we need to update $wpdb->taxonomy to the correct table
         * ourself.
         *
         * @return none
         */
        function update_wpdb() {
                global $wpdb;
                $wpdb->taxonomymeta = $wpdb->prefix . 'taxonomymeta';
        }     

        /**   
         * Create a table for taxonomy meta
         *
         * @return none
         */
        function create_taxonomy_meta_table() {
                if ( $this->taxonomy_meta_table_exists() ) {
                        return;
                }     
                global $wpdb;
                $query = "CREATE TABLE `{$wpdb->prefix}taxonomymeta` (
                           `meta_id` bigint(20) unsigned not null auto_increment,
                           `taxonomy_id` bigint(20) unsigned not null default '0',
                           `meta_key` varchar(255),
                           `meta_value` longtext,
                           PRIMARY KEY (`meta_id`),
                           KEY `taxonomy_id` (`taxonomy_id`),
                           KEY `meta_key` (`meta_key`)
                        ) ENGINE=MyISAM DEFAULT CHARSET=utf8 AUTO_INCREMENT=2;";
                $r = $wpdb->query( $wpdb->prepare( $query ) );
        }     

        /**   
         * Check if the taxonomy meta table exists
         *
         * @return bool table exists
         */
        function taxonomy_meta_table_exists() {
                global $wpdb;
                $query = "SHOW TABLES LIKE '{$wpdb->prefix}taxonomymeta';";
                $indexes = $wpdb->get_var( $wpdb->prepare( $query ) );
                if ( $indexes )
                        return true; 
                return false;
        }     

}
?>