/*
  WARNING: Try and only run this once, and only after the Download Monitor upgrade as been run.
  Also, I cannot guarantee that this will not break everything, so please use with caution!
*/
function ebd_upgrade_from_legacy()
{
    global $wpdb;

    $content_items = $wpdb->get_results( "SELECT content_id FROM `" . $wpdb->prefix . DLM_LU_Content_Queue::TABLE . "`" );

    $id_map = array();

    foreach ( $content_items as $item )
    {
        $post = get_post( $item->content_id );

        // content
        $content = $post->post_content;

        // generate new content
        $regex = "`\[email-download ([^\]]*)(?:download_id=([\"|']{0,1})([0-9]+)(?:[\"|']{0,1}))([^\]]*)\]`";
        $new_content = preg_replace_callback( $regex, function ( $m ) use ( $id_map, $wpdb ) {
            // check map, if not in map, fetch
            if ( ! isset( $id_map[ $m[3] ] ) ) {
                $new_id = absint( $wpdb->get_var( $wpdb->prepare( "SELECT `new_id` FROM `" . $wpdb->prefix . DLM_LU_Download_Queue::TABLE  . "` WHERE `legacy_id` = %d ", absint( $m[3] ) ) ) );

                if ( ! $new_id )
                    return $m[0];

                $id_map[ $m[3] ] = $new_id;
            }
            return "[email-download " . $m[1] . "download_id=" . $m[2] . $id_map[ $m[3] ] . $m[2] . $m[4] . "]";
        }, $content );

        if ( $content !== $new_content )
            $wpdb->update( $wpdb->posts, array( 'post_content' => $new_content ), array( 'ID' => $post->ID ), array( '%s' ), array( '%d' ) );
    }
}
if ( $_GET['ebd_upgrade'] == 'upgrade' )
    ebd_upgrade_from_legacy();