<?php
/**
* Base class for upgrade checks
* 
* @package IWP
*/
class iwp_upgradeprocess extends iwp_base
{

	/**
	* @var $error The last error message
	*/
	public $error = '';
	public $errormessage = null;

	/**
	* The last warning message, or null if not set
	*
	* @var string
	*/
	public $warningmessage = null;

	/**
	* CheckUpgrade stub function
	*
	* @return boolean returns false if we need to run the upgrade function
	*/
	public function CheckUpgrade() {}
	public function IgnoreError($mysqlError) { return false; }

	/**
	* Check if a database table exists
	*
	* @param string $table The table name to check
	*
	* @return boolean If the table exists return true
	*/
	public function TableExists($table)
	{
		$query = "SHOW TABLES LIKE '".$table."'";
		$result = $this->db->FetchOne($query);
		// If there is a table with this name already we don't need to run this
		// part of the upgrade script

		// We have to convert the name to lower case before comparing since
		// if MySQL is on windows the tables are converted to lowercase
		// when they are returned from our sql statement
		if (strtolower($result) == strtolower($table)) {
			return true;
		} else {
			return false;
		}
	}

	/**
	* Check if a column exists in a table
	*
	* @param $table The table with the column we are checking for
	* @param $column The column to check for
	*
	* @return boolean If the column exists in the table return true
	*/
	public function ColumnExists($table, $column)
	{
		$query = 'SHOW COLUMNS FROM '.$table." LIKE '".$column."'";

		$result = $this->db->Query($query);
		$row = $this->db->Fetch($result);

		if ($row['Field'] == $column) {
			return true;
		} else {
			return false;
		}
	}

	/**
	* GetIndexInfo
	*
	* Get information about the indexes on $table and return an array with
	* this information
	*
	* @param string $table The name of the table to get information about the indexes for
	*
	* @return array The array containing the index information in the format
		$indexes = array (
			'indexname' => array (
				'unique' => true/false,
				'type' => btree/fulltext,
				'columns' = array (
					'field1',
					'field2',
					'field3',
				),
			),
			'index2name' => array (
				...
			),
		)
	*/
	public function GetIndexInfo($table)
	{
		$indexes = array();

		$query = 'SHOW INDEX FROM '.$table;
		$result = $this->db->Query($query);
		if ($result === false) {
			return array();
		}
		while ($row = $this->db->Fetch($result)) {
			if (!isset($indexes[$row['Key_name']])) {
				if (!isset($row['Index_type'])) {
					$row['Index_type'] = 'UNDEFINED';
				}

				$indexes[$row['Key_name']] = array (
					'unique' => ($row['Non_unique'] == 0),
					'type' => $row['Index_type'],
				);

				if (!isset($indexes[$row['Key_name']]['columns'])
				|| !is_array($indexes[$row['Key_name']]['columns'])) {
					$indexes[$row['Key_name']]['columns'] = array();
				}
			}

			$indexes[$row['Key_name']]['columns'][] = $row['Column_name'];
		}
		return $indexes;
	}

	/**
	* IndexExists
	*
	* Check if an index exists on some table columns
	*
	* @param string $table The name of the table
	* @param array $columns The array of column names the index is on. Order counts.
	* @param bool $unique Is the index a unique index ?
	* @param string $type The type of index to check for (BTREE or FULLTEXT)
	*
	* @return bool Does the index exist as expected or not ?
	*/
	public function IndexExists($table, $columns, $unique=false, $type='BTREE')
	{
		$keymatches = array();
		$indexname = '';

		if (empty($table)) {
			$this->error = 'Table name is empty';
			return false;
		}

		if (empty($columns)) {
			$this->error = 'Columns is empty';
			return false;
		}

		if (!is_array($columns)) {
			$columns = (array)$columns;
		}

		if (!in_array($type, array('BTREE', 'FULLTEXT', 'UNDEFINED'))) {
			$this->error = 'Type of index was not an expected type';
			return false;
		}

		$indexes = $this->GetIndexInfo($table);

		if (empty($indexes)) {
			$this->error = 'Could not get index information';
			return false;
		}

		foreach ($indexes as $name => $index) {
			// Since MySQL can use the first part of the array, lets check
			// to see if the required index is already part of another index
			$slice = array_slice($index['columns'], 0, count($columns));

			// Check if the index is one we can use
			if (($index['type'] == $type || $index['type'] == 'UNDEFINED')
			&& $slice == $columns) {
				return true;
			}
		}
		return false;
	}

}