<?php
/**
 * Joomla! Content Management System
 *
 * @copyright  Copyright (C) 2005 - 2017 Open Source Matters, Inc. All rights reserved.
 * @license    GNU General Public License version 2 or later; see LICENSE.txt
 */

namespace Joomla\CMS\Schema\ChangeItem;

defined('JPATH_PLATFORM') or die;

use Joomla\CMS\Schema\ChangeItem;

/**
 * Checks the database schema against one SQL Server DDL query to see if it has been run.
 *
 * @since  2.5
 */
class SqlsrvChangeItem extends ChangeItem
{
	/**
	 * Checks a DDL query to see if it is a known type
	 * If yes, build a check query to see if the DDL has been run on the database.
	 * If successful, the $msgElements, $queryType, $checkStatus and $checkQuery fields are populated.
	 * The $msgElements contains the text to create the user message.
	 * The $checkQuery contains the SQL query to check whether the schema change has
	 * been run against the current database. The $queryType contains the type of
	 * DDL query that was run (for example, CREATE_TABLE, ADD_COLUMN, CHANGE_COLUMN_TYPE, ADD_INDEX).
	 * The $checkStatus field is set to zero if the query is created
	 *
	 * If not successful, $checkQuery is empty and , and $checkStatus is -1.
	 * For example, this will happen if the current line is a non-DDL statement.
	 *
	 * @return void
	 *
	 * @since  2.5
	 */
	protected function buildCheckQuery()
	{
		// Initialize fields in case we can't create a check query
		$this->checkStatus = -1; // change status to skipped
		$result = null;

		// Remove any newlines
		$this->updateQuery = str_replace("\n", '', $this->updateQuery);

		// Fix up extra spaces around () and in general
		$find = array('#((\s*)\(\s*([^)\s]+)\s*)(\))#', '#(\s)(\s*)#');
		$replace = array('($3)', '$1');
		$updateQuery = preg_replace($find, $replace, $this->updateQuery);
		$wordArray = explode(' ', $updateQuery);

		// First, make sure we have an array of at least 6 elements
		// if not, we can't make a check query for this one
		if (count($wordArray) < 6)
		{
			// Done with method
			return;
		}

		// We can only make check queries for alter table and create table queries
		$command = strtoupper($wordArray[0] . ' ' . $wordArray[1]);

		if ($command === 'ALTER TABLE')
		{
			$alterCommand = strtoupper($wordArray[3] . ' ' . $wordArray[4]);

			if ($alterCommand === 'ADD')
			{
				$result = 'SELECT * FROM INFORMATION_SCHEMA.Columns ' . $wordArray[2] . ' WHERE COLUMN_NAME = ' . $this->fixQuote($wordArray[5]);
				$this->queryType = 'ADD';
				$this->msgElements = array($this->fixQuote($wordArray[2]), $this->fixQuote($wordArray[5]));
			}
			elseif ($alterCommand === 'CREATE INDEX')
			{
				$index = $this->fixQuote(substr($wordArray[5], 0, strpos($wordArray[5], '(')));
				$result = 'SELECT * FROM SYS.INDEXES ' . $wordArray[2] . ' WHERE name = ' . $index;
				$this->queryType = 'CREATE INDEX';
				$this->msgElements = array($this->fixQuote($wordArray[2]), $index);
			}
			elseif (strtoupper($wordArray[3]) === 'MODIFY' || strtoupper($wordArray[3]) === 'CHANGE')
			{
				$result = 'SELECT COLUMN_NAME FROM INFORMATION_SCHEMA.COLUMNS  WHERE table_name = ' . $this->fixQuote($wordArray[2]);
				$this->queryType = 'ALTER COLUMN COLUMN_NAME =' . $this->fixQuote($wordArray[4]);
				$this->msgElements = array($this->fixQuote($wordArray[2]), $this->fixQuote($wordArray[4]));
			}
		}

		if ($command === 'CREATE TABLE')
		{
			$table = $wordArray[2];
			$result = 'SELECT * FROM sys.TABLES WHERE NAME = ' . $this->fixQuote($table);
			$this->queryType = 'CREATE_TABLE';
			$this->msgElements = array($this->fixQuote($table));
		}

		// Set fields based on results
		if ($this->checkQuery = $result)
		{
			// Unchecked status
			$this->checkStatus = 0;
		}
		else
		{
			// Skipped
			$this->checkStatus = -1;
		}
	}

	/**
	 * Fix up integer. Fixes problem with MySQL integer descriptions.
	 * If you change a column to "integer unsigned" it shows
	 * as "int(10) unsigned" in the check query.
	 *
	 * @param   string  $type1  the column type
	 * @param   string  $type2  the column attributes
	 *
	 * @return  string  The original or changed column type.
	 *
	 * @since   2.5
	 */
	private function fixInteger($type1, $type2)
	{
		$result = $type1;

		if (strtolower($type1) === 'integer' && strtolower(substr($type2, 0, 8)) === 'unsigned')
		{
			$result = 'int';
		}

		return $result;
	}

	/**
	 * Fixes up a string for inclusion in a query.
	 * Replaces name quote character with normal quote for literal.
	 * Drops trailing semicolon. Injects the database prefix.
	 *
	 * @param   string  $string  The input string to be cleaned up.
	 *
	 * @return  string  The modified string.
	 *
	 * @since   2.5
	 */
	private function fixQuote($string)
	{
		$string = str_replace('[', '', $string);
		$string = str_replace(']', '', $string);
		$string = str_replace('`', '', $string);
		$string = str_replace(';', '', $string);
		$string = str_replace('#__', $this->db->getPrefix(), $string);

		return $this->db->quote($string);
	}
}
