slideshow-upgrade.php

<?php

add_action('init', 'bu_slideshow_upgrade', 99);

/**
 * Run any appropriate upgrade routines for the current version &
 * update version number in site options
 */
function bu_slideshow_upgrade() {
	$current_version = get_option('bu_slideshow_version');
	$upgrade_firstrun = ( FALSE === $current_version && version_compare('2.3', BU_SLIDESHOW_VERSION, '<=') );
	$update_to_latest = ( -1 === version_compare($current_version, BU_SLIDESHOW_VERSION ) );

	if ( $upgrade_firstrun || $update_to_latest ) {
		update_option('bu_slideshow_version', BU_SLIDESHOW_VERSION);
		if( $upgrade_firstrun || -1 === version_compare($current_version, '2.3' ) ){
			bu_slideshow_migrate_shows();
		}
	}
}

/**
 *  Move slideshows to individual site options
 */
function bu_slideshow_migrate_shows() {
	$all_slideshows = get_option( 'bu_slideshows' , array() );
	$has_errors = FALSE;
	$slideshow_id_map_option = 'bu_slideshow_id_map';
	$map = get_option( $slideshow_id_map_option );

	if( FALSE === $map ){
		$map = array();
		add_option( $slideshow_id_map_option, $map, '', false );
	}

	foreach ($all_slideshows as $k => $show) {
		if( ! intval( $show->id ) ){
			$has_errors = TRUE;
			error_log( sprintf( '[%s] Invalid Slideshow ID: %d Object: %s',
				__FUNCTION__, $show->id, var_export( $show, TRUE ) ) );
			continue;
		}

		$postID = bu_slideshow_create_post( $show, $map );

		if( FALSE !== $postID ){
			$map[ $show->id ] = $postID;
		}
	}

	// Wrap-up
	if( ! $has_errors ){
		// delete_option( 'bu_slideshows' );
		update_option( $slideshow_id_map_option, $map );
	}
}

function bu_slideshow_create_post( $show, $map ){
	$result = $postID = $show->create_post();

	if( FALSE === $result ){
		error_log( sprintf( '[%s] Error creating post: %s Object: %s',
			__FUNCTION__, $result->get_error_message(), var_export( $show, TRUE ) ) );
		return FALSE;
	} else if( array_key_exists( $postID, $map ) ){
		error_log( sprintf( '[%s] Error creating post: Slideshow ID %d exists. Map: %s',
			__FUNCTION__, $postID, var_export( $map, TRUE ) ) );
		return bu_slideshow_create_post( $show, $map );	
	}

	return $postID;
}