<?php

/**

 * Plugins may load this file to gain access to special helper functions for

 * plugin installation. This file is not included by WordPress and it is

 * recommended, to prevent fatal errors, that this file is included using

 * require_once().

 *

 * These functions are not optimized for speed, but they should only be used

 * once in a while, so speed shouldn't be a concern. If it is and you are

 * needing to use these functions a lot, you might experience time outs. If you

 * do, then it is advised to just write the SQL code yourself.

 *

 * <code>

 * check_column('wp_links', 'link_description', 'mediumtext');

 * if (check_column($wpdb->comments, 'comment_author', 'tinytext'))

 *     echo "ok\n";

 *

 * $error_count = 0;

 * $tablename = $wpdb->links;

 * // check the column

 * if (!check_column($wpdb->links, 'link_description', 'varchar(255)')) {

 *     $ddl = "ALTER TABLE $wpdb->links MODIFY COLUMN link_description varchar(255) NOT NULL DEFAULT '' ";

 *     $q = $wpdb->query($ddl);

 * }

 *

 * if (check_column($wpdb->links, 'link_description', 'varchar(255)')) {

 *     $res .= $tablename . ' - ok <br />';

 * } else {

 *     $res .= 'There was a problem with ' . $tablename . '<br />';

 *     ++$error_count;

 * }

 * </code>

 *

 * @package WordPress

 * @subpackage Plugin

 */

/** Load WordPress Bootstrap */

require_once(dirname(dirname(__FILE__)).'/wp-load.php');

if ( ! function_exists('maybe_create_table') ) :

/**

 * Create database table, if it doesn't already exist.

 *

 * @package WordPress

 * @subpackage Plugin

 * @uses $wpdb

 *

 * @param string $table_name Database table name.

 * @param string $create_ddl Create database table SQL.

 * @return bool False on error, true if already exists or success.

 */

function maybe_create_table($table_name, $create_ddl) {

	global $wpdb;

	foreach ($wpdb->get_col("SHOW TABLES",0) as $table ) {

		if ($table == $table_name) {

			return true;

		}

	}

	//didn't find it try to create it.

	$wpdb->query($create_ddl);

	// we cannot directly tell that whether this succeeded!

	foreach ($wpdb->get_col("SHOW TABLES",0) as $table ) {

		if ($table == $table_name) {

			return true;

		}

	}

	return false;

}

endif;

if ( ! function_exists('maybe_add_column') ) :

/**

 * Add column to database table, if column doesn't already exist in table.

 *

 * @package WordPress

 * @subpackage Plugin

 * @uses $wpdb

 *

 * @param string $table_name Database table name

 * @param string $column_name Table column name

 * @param string $create_ddl SQL to add column to table.

 * @return bool False on failure. True, if already exists or was successful.

 */

function maybe_add_column($table_name, $column_name, $create_ddl) {

	foreach ($wpdb->get_col("DESC $table_name",0) as $column ) {

		if ($column == $column_name) {

			return true;

		}

	}

	//didn't find it try to create it.

	$wpdb->query($create_ddl);

	// we cannot directly tell that whether this succeeded!

	foreach ($wpdb->get_col("DESC $table_name",0) as $column ) {

		if ($column == $column_name) {

			return true;

		}

	}

	return false;

}

endif;

/**

 * Drop column from database table, if it exists.

 *

 * @package WordPress

 * @subpackage Plugin

 * @uses $wpdb

 *

 * @param string $table_name Table name

 * @param string $column_name Column name

 * @param string $drop_ddl SQL statement to drop column.

 * @return bool False on failure, true on success or doesn't exist.

 */

function maybe_drop_column($table_name, $column_name, $drop_ddl) {

	global $wpdb;

	foreach ($wpdb->get_col("DESC $table_name",0) as $column ) {

		if ($column == $column_name) {

			//found it try to drop it.

			$wpdb->query($drop_ddl);

			// we cannot directly tell that whether this succeeded!

			foreach ($wpdb->get_col("DESC $table_name",0) as $column ) {

				if ($column == $column_name) {

					return false;

				}

			}

		}

	}

	// else didn't find it

	return true;

}

/**

 * Check column matches criteria.

 *

 * Uses the SQL DESC for retrieving the table info for the column. It will help

 * understand the parameters, if you do more research on what column information

 * is returned by the SQL statement. Pass in null to skip checking that

 * criteria.

 *

 * Column names returned from DESC table are case sensitive and are listed:

 *      Field

 *      Type

 *      Null

 *      Key

 *      Default

 *      Extra

 *

 * @package WordPress

 * @subpackage Plugin

 *

 * @param string $table_name Table name

 * @param string $col_name Column name

 * @param string $col_type Column type

 * @param bool $is_null Optional. Check is null.

 * @param mixed $key Optional. Key info.

 * @param mixed $default Optional. Default value.

 * @param mixed $extra Optional. Extra value.

 * @return bool True, if matches. False, if not matching.

 */

function check_column($table_name, $col_name, $col_type, $is_null = null, $key = null, $default = null, $extra = null) {

	$diffs = 0;

	$results = $wpdb->get_results("DESC $table_name");

	foreach ($results as $row ) {

		if ($row->Field == $col_name) {

			// got our column, check the params

			if (($col_type != null) && ($row->Type != $col_type)) {

				++$diffs;

			}

			if (($is_null != null) && ($row->Null != $is_null)) {

				++$diffs;

			}

			if (($key != null) && ($row->Key  != $key)) {

				++$diffs;

			}

			if (($default != null) && ($row->Default != $default)) {

				++$diffs;

			}

			if (($extra != null) && ($row->Extra != $extra)) {

				++$diffs;

			}

			if ($diffs > 0) {

				return false;

			}

			return true;

		} // end if found our column

	}

	return false;

}