<?php
/**
 * Microsoft SQL Server 2008+ connector class.
 *
 * <h2>Connecting using Windows</h2>
 *
 * If you've got your website running on Windows, it's highly recommended you
 * use Microsoft SQL Server Driver for PHP "sqlsrv".
 *
 * A complete guide to installing a Windows IIS + PHP + SQL Server web stack can be
 * found here: http://doc.silverstripe.org/installation-on-windows-server-manual-iis
 *
 * @see http://sqlsrvphp.codeplex.com/
 *
 * <h2>Connecting using Linux or Mac OS X</h2>
 *
 * The following commands assume you used the default package manager
 * to install PHP with the operating system.
 *
 * Debian, and Ubuntu:
 * <code>apt-get install php5-sybase</code>
 *
 * Fedora, CentOS and RedHat:
 * <code>yum install php-mssql</code>
 *
 * Mac OS X (MacPorts):
 * <code>port install php5-mssql</code>
 *
 * These packages will install the mssql extension for PHP, as well
 * as FreeTDS, which will let you connect to SQL Server.
 *
 * More information available in the SilverStripe developer wiki:
 * @see http://doc.silverstripe.org/modules:mssql
 * @see http://doc.silverstripe.org/installation-on-windows-server-manual-iis
 *
 * References:
 * @see http://freetds.org
 *
 * @package mssql
 */
class MSSQLDatabase extends SS_Database {

	/**
	 * Words that will trigger an error if passed to a SQL Server fulltext search
	 */
	public static $noiseWords = array('about', '1', 'after', '2', 'all', 'also', '3', 'an', '4', 'and', '5', 'another', '6', 'any', '7', 'are', '8', 'as', '9', 'at', '0', 'be', '$', 'because', 'been', 'before', 'being', 'between', 'both', 'but', 'by', 'came', 'can', 'come', 'could', 'did', 'do', 'does', 'each', 'else', 'for', 'from', 'get', 'got', 'has', 'had', 'he', 'have', 'her', 'here', 'him', 'himself', 'his', 'how', 'if', 'in', 'into', 'is', 'it', 'its', 'just', 'like', 'make', 'many', 'me', 'might', 'more', 'most', 'much', 'must', 'my', 'never', 'no', 'now', 'of', 'on', 'only', 'or', 'other', 'our', 'out', 'over', 're', 'said', 'same', 'see', 'should', 'since', 'so', 'some', 'still', 'such', 'take', 'than', 'that', 'the', 'their', 'them', 'then', 'there', 'these', 'they', 'this', 'those', 'through', 'to', 'too', 'under', 'up', 'use', 'very', 'want', 'was', 'way', 'we', 'well', 'were', 'what', 'when', 'where', 'which', 'while', 'who', 'will', 'with', 'would', 'you', 'your', 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z');

	/**
	 * Transactions will work with FreeTDS, but not entirely with sqlsrv driver on Windows with MARS enabled.
	 * TODO:
	 * - after the test fails with open transaction, the transaction should be rolled back,
	 *   otherwise other tests will break claiming that transaction is still open.
	 * - figure out SAVEPOINTS
	 * - READ ONLY transactions
	 */
	protected $supportsTransactions = true;

	/**
	 * Cached flag to determine if full-text is enabled. This is set by
	 * {@link MSSQLDatabase::fullTextEnabled()}
	 *
	 * @var boolean
	 */
	protected $fullTextEnabled = null;

	/**
	 * Set the default collation of the MSSQL nvarchar fields that we create.
	 * We don't apply this to the database as a whole, so that we can use unicode collations.
	 * 
	 * @param string $collation
	 */
	public static function set_collation($collation) {
		Config::inst()->update('MSSQLDatabase', 'collation', $collation);
	}
	
	/**
	 * The default collation of the MSSQL nvarchar fields that we create.
	 * We don't apply this to the database as a whole, so that we can use
	 * unicode collations.
	 * 
	 * @return string
	 */
	public static function get_collation() {
		return Config::inst()->get('MSSQLDatabase', 'collation');
	}

	/**
	 * Connect to a MS SQL database.
	 * @param array $parameters An map of parameters, which should include:
	 *  - server: The server, eg, localhost
	 *  - username: The username to log on with
	 *  - password: The password to log on with
	 *  - database: The database to connect to
	 *  - windowsauthentication: Set to true to use windows authentication 
	 *    instead of username/password
	 */
	public function connect($parameters) {
		parent::connect($parameters);

		// Configure the connection
		$this->query('SET QUOTED_IDENTIFIER ON');
		$this->query('SET TEXTSIZE 2147483647');
	}

	/**
	 * Checks whether the current SQL Server version has full-text
	 * support installed and full-text is enabled for this database.
	 *
	 * @return boolean
	 */
	public function fullTextEnabled() {
		if($this->fullTextEnabled === null) {
			$this->fullTextEnabled = $this->updateFullTextEnabled();
		}
		return $this->fullTextEnabled;
	}
	
	/**
	 * Checks whether the current SQL Server version has full-text
	 * support installed and full-text is enabled for this database.
	 *
	 * @return boolean
	 */
	protected function updateFullTextEnabled() {
		// Check if installed
		$isInstalled = $this->query("SELECT fulltextserviceproperty('isfulltextinstalled')")->value();
		if(!$isInstalled) return false;
		
		// Check if current database is enabled
		$database = $this->getSelectedDatabase();
		$enabledForDb = $this->preparedQuery(
			"SELECT is_fulltext_enabled FROM sys.databases WHERE name = ?",
			array($database)
		)->value();
		return $enabledForDb;
	}

	public function supportsCollations() {
		return true;
	}

	public function supportsTimezoneOverride() {
		return true;
	}

	public function getDatabaseServer() {
		return "sqlsrv";
	}
	
	public function selectDatabase($name, $create = false, $errorLevel = E_USER_ERROR) {
		$this->fullTextEnabled = null;
		
		return parent::selectDatabase($name, $create, $errorLevel);
	}

	public function clearTable($table) {
		$this->query("TRUNCATE TABLE \"$table\"");
	}

	/**
	 * SQL Server uses CURRENT_TIMESTAMP for the current date/time.
	 */
	function now() {
		return 'CURRENT_TIMESTAMP';
	}

	/**
	 * Returns the database-specific version of the random() function
	 */
	function random(){
		return 'RAND()';
	}

	/**
	 * The core search engine configuration.
	 * Picks up the fulltext-indexed tables from the database and executes search on all of them.
	 * Results are obtained as ID-ClassName pairs which is later used to reconstruct the DataObjectSet.
	 *
	 * @param array classesToSearch computes all descendants and includes them. Check is done via WHERE clause.
	 * @param string $keywords Keywords as a space separated string
	 * @return object DataObjectSet of result pages
	 */
	public function searchEngine($classesToSearch, $keywords, $start, $pageLength, $sortBy = "Relevance DESC", $extraFilter = "", $booleanSearch = false, $alternativeFileFilter = "", $invertedMatch = false) {
		if(isset($objects)) $results = new ArrayList($objects);
		else $results = new ArrayList();

		if (!$this->fullTextEnabled()) return $results;
		if (!in_array(substr($sortBy, 0, 9), array('"Relevanc', 'Relevance'))) user_error("Non-relevance sort not supported.", E_USER_ERROR);

		$allClassesToSearch = array();
		foreach ($classesToSearch as $class) {
			$allClassesToSearch = array_merge($allClassesToSearch, array_values(ClassInfo::dataClassesFor($class)));
		}
		$allClassesToSearch = array_unique($allClassesToSearch);

		//Get a list of all the tables and columns we'll be searching on:
		$fulltextColumns = $this->query('EXEC sp_help_fulltext_columns');
		$queries = array();

		// Sort the columns back into tables.
		$tables = array();
		foreach($fulltextColumns as $column) {
			// Skip extension tables.
			if(substr($column['TABLE_NAME'], -5) == '_Live' || substr($column['TABLE_NAME'], -9) == '_versions') continue;

			// Add the column to table.
			$table = &$tables[$column['TABLE_NAME']];
			if (!$table) {
				$table = array($column['FULLTEXT_COLUMN_NAME']);
			} else {
				array_push($table, $column['FULLTEXT_COLUMN_NAME']);
			}
		}

		// Create one query per each table, $columns not used. We want just the ID and the ClassName of the object from this query.
		foreach($tables as $tableName => $columns){
			$baseClass = ClassInfo::baseDataClass($tableName);

			$join = $this->fullTextSearchMSSQL($tableName, $keywords);
			if (!$join) return $results; // avoid "Null or empty full-text predicate"

			// Check if we need to add ShowInSearch
			$where = null;
			if(strpos($tableName, 'SiteTree') === 0) {
				$where = array("\"$tableName\".\"ShowInSearch\"!=0");
			} elseif(strpos($tableName, 'File') === 0) {
				// File.ShowInSearch was added later, keep the database driver backwards compatible
				// by checking for its existence first
				$fields = $this->fieldList($tableName);
				if(array_key_exists('ShowInSearch', $fields)) {
					$where = array("\"$tableName\".\"ShowInSearch\"!=0");
				}
			}

			$queries[$tableName] = DataList::create($tableName)->where($where, '')->dataQuery()->query();
			$queries[$tableName]->setOrderBy(array());
			
			// Join with CONTAINSTABLE, a full text searcher that includes relevance factor
			$queries[$tableName]->setFrom(array("\"$tableName\" INNER JOIN $join AS \"ft\" ON \"$tableName\".\"ID\"=\"ft\".\"KEY\""));
			// Join with the base class if needed, as we want to test agains the ClassName
			if ($tableName != $baseClass) {
				$queries[$tableName]->setFrom("INNER JOIN \"$baseClass\" ON  \"$baseClass\".\"ID\"=\"$tableName\".\"ID\"");
			}

			$queries[$tableName]->setSelect(array("\"$tableName\".\"ID\""));
			$queries[$tableName]->selectField("'$tableName'", 'Source');
			$queries[$tableName]->selectField('Rank', 'Relevance');
			if ($extraFilter) {
				$queries[$tableName]->addWhere($extraFilter);
			}
			if (count($allClassesToSearch)) {
				$classesPlaceholder = DB::placeholders($allClassesToSearch);
				$queries[$tableName]->addWhere(array(
					"\"$baseClass\".\"ClassName\" IN ($classesPlaceholder)" =>
					$allClassesToSearch
				));
			}
			// Reset the parameters that would get in the way
		}

		// Generate SQL
		$querySQLs = array();
		$queryParameters = array();
		foreach($queries as $query) {
			$querySQLs[] = $query->sql($parameters);
			$queryParameters = array_merge($queryParameters, $parameters);
		}

		// Unite the SQL
		$fullQuery = implode(" UNION ", $querySQLs) . " ORDER BY $sortBy";

		// Perform the search
		$result = $this->preparedQuery($fullQuery, $queryParameters);

		// Regenerate DataObjectSet - watch out, numRecords doesn't work on sqlsrv driver on Windows.
		$current = -1;
		$objects = array();
		foreach ($result as $row) {
			$current++;

			// Select a subset for paging
			if ($current >= $start && $current < $start + $pageLength) {
				$objects[] = DataObject::get_by_id($row['Source'], $row['ID']);
			}
		}

		if(isset($objects)) $results = new ArrayList($objects);
		else $results = new ArrayList();
		$list = new PaginatedList($results);
		$list->setPageStart($start);
		$list->setPageLength($pageLength);
		$list->setTotalItems($current+1);
		return $list;
	}

	/**
	 * Allow auto-increment primary key editing on the given table.
	 * Some databases need to enable this specially.
	 * 
	 * @param $table The name of the table to have PK editing allowed on
	 * @param $allow True to start, false to finish
	 */
	function allowPrimaryKeyEditing($table, $allow = true) {
		$this->query("SET IDENTITY_INSERT \"$table\" " . ($allow ? "ON" : "OFF"));
	}

	/**
	 * Returns a SQL fragment for querying a fulltext search index
	 *
	 * @param $tableName specific - table name
	 * @param $keywords string The search query
	 * @param $fields array The list of field names to search on, or null to include all
	 *
	 * @returns null if keyword set is empty or the string with JOIN clause to be added to SQL query
	 */
	public function fullTextSearchMSSQL($tableName, $keywords, $fields = null) {
		// Make sure we are getting an array of fields
		if (isset($fields) && !is_array($fields)) $fields = array($fields);

		// Strip unfriendly characters, SQLServer "CONTAINS" predicate will crash on & and | and ignore others anyway.
		if (function_exists('mb_ereg_replace')) {
			$keywords = mb_ereg_replace('[^\w\s]', '', trim($keywords));
		} else {
			$keywords = $this->escapeString(str_replace(array('&','|','!','"','\''), '', trim($keywords)));
		}

		// Remove stopwords, concat with ANDs
		$keywordList = explode(' ', $keywords);
		$keywordList = $this->removeStopwords($keywordList);
		
		// remove any empty values from the array
		$keywordList = array_filter($keywordList);
		if(empty($keywordList)) return null;

		$keywords = implode(' AND ', $keywordList);
		if ($fields) $fieldNames = '"' . implode('", "', $fields) . '"';
		else $fieldNames = "*";

		return "CONTAINSTABLE(\"$tableName\", ($fieldNames), '$keywords')";
	}

	/**
	 * Remove stopwords that would kill a MSSQL full-text query
	 *
	 * @param array $keywords
	 *
	 * @return array $keywords with stopwords removed
	 */
	public function removeStopwords($keywords) {
		$goodKeywords = array();
		foreach($keywords as $keyword) {
			if (in_array($keyword, self::$noiseWords)) continue;
			$goodKeywords[] = trim($keyword);
		}
		return $goodKeywords;
	}

	/**
	 * Does this database support transactions?
	 */
	public function supportsTransactions(){
		return $this->supportsTransactions;
	}

	/**
	 * This is a quick lookup to discover if the database supports particular extensions
	 * Currently, MSSQL supports no extensions
	 * 
	 * @param array $extensions List of extensions to check for support of. The key of this array
	 * will be an extension name, and the value the configuration for that extension. This
	 * could be one of partitions, tablespaces, or clustering
	 * @return boolean Flag indicating support for all of the above
	 */
	public function supportsExtensions($extensions = array('partitions', 'tablespaces', 'clustering')){
		if(isset($extensions['partitions']))
			return false;
		elseif(isset($extensions['tablespaces']))
			return false;
		elseif(isset($extensions['clustering']))
			return false;
		else
			return false;
	}
	
	/**
	 * Start transaction. READ ONLY not supported.
	 */
	public function transactionStart($transactionMode = false, $sessionCharacteristics = false){
		if($this->connector instanceof SQLServerConnector) {
			$this->connector->transactionStart();
		} else {
			$this->query('BEGIN TRANSACTION');
		}
	}

	public function transactionSavepoint($savepoint){
		$this->query("SAVE TRANSACTION \"$savepoint\"");
	}

	public function transactionRollback($savepoint = false) {
		if($savepoint) {
			$this->query("ROLLBACK TRANSACTION \"$savepoint\"");
		} elseif($this->connector instanceof SQLServerConnector) {
			 $this->connector->transactionRollback();
		} else {
			$this->query('ROLLBACK TRANSACTION');
		}
	}
	
	public function transactionEnd($chain = false) {
		if($this->connector instanceof SQLServerConnector) {
			$this->connector->transactionEnd();
		} else {
			$this->query('COMMIT TRANSACTION');
		}
	}
	
	public function comparisonClause($field, $value, $exact = false, $negate = false, $caseSensitive = null, $parameterised = false) {
		if($exact) {
			$comp = ($negate) ? '!=' : '=';
		} else {
			$comp = 'LIKE';
			if($negate) $comp = 'NOT ' . $comp;	
		}
		
		// Field definitions are case insensitive by default,
		// change used collation for case sensitive searches.
		$collateClause = '';
		if($caseSensitive === true) {
			if(self::get_collation()) {
				$collation = preg_replace('/_CI_/', '_CS_', self::get_collation());
			} else {
				$collation = 'Latin1_General_CS_AS';
			}
			$collateClause = ' COLLATE ' . $collation;
		} elseif($caseSensitive === false) {
			if(self::get_collation()) {
				$collation = preg_replace('/_CS_/', '_CI_', self::get_collation());
			} else {
				$collation = 'Latin1_General_CI_AS';
			}
			$collateClause = ' COLLATE ' . $collation;
		}

		$clause = sprintf("%s %s %s", $field, $comp, $parameterised ? '?' : "'$value'");
		if($collateClause) $clause .= $collateClause;

		return $clause;
	}

	/**
	 * Function to return an SQL datetime expression for MSSQL
	 * used for querying a datetime in a certain format
	 * 
	 * @param string $date to be formated, can be either 'now', literal datetime like '1973-10-14 10:30:00' or field name, e.g. '"SiteTree"."Created"'
	 * @param string $format to be used, supported specifiers:
	 * %Y = Year (four digits)
	 * %m = Month (01..12)
	 * %d = Day (01..31)
	 * %H = Hour (00..23)
	 * %i = Minutes (00..59)
	 * %s = Seconds (00..59)
	 * %U = unix timestamp, can only be used on it's own
	 * @return string SQL datetime expression to query for a formatted datetime
	 */
	function formattedDatetimeClause($date, $format) {
		preg_match_all('/%(.)/', $format, $matches);
		foreach($matches[1] as $match) if(array_search($match, array('Y','m','d','H','i','s','U')) === false) user_error('formattedDatetimeClause(): unsupported format character %' . $match, E_USER_WARNING);

		if(preg_match('/^now$/i', $date)) {
			$date = "CURRENT_TIMESTAMP";
		} else if(preg_match('/^\d{4}-\d{2}-\d{2} \d{2}:\d{2}:\d{2}$/i', $date)) {
			$date = "'$date.000'";
		}

		if($format == '%U') {
			return "DATEDIFF(s, '1970-01-01 00:00:00', DATEADD(hour, DATEDIFF(hour, GETDATE(), GETUTCDATE()), $date))";
		}

		$trans = array(
			'Y' => 'yy',
			'm' => 'mm',
			'd' => 'dd',
			'H' => 'hh',
			'i' => 'mi',
			's' => 'ss',
		);

		$strings = array();
		$buffer = $format;
		while(strlen($buffer)) {
			if(substr($buffer,0,1) == '%') {
				$f = substr($buffer,1,1);
				$flen = $f == 'Y' ? 4 : 2;
				$strings[] = "RIGHT('0' + CAST(DATEPART({$trans[$f]},$date) AS VARCHAR), $flen)";
				$buffer = substr($buffer, 2);
			} else {
				$pos = strpos($buffer, '%');
				if($pos === false) {
					$strings[] = $buffer;
					$buffer = '';
				} else {
					$strings[] = "'".substr($buffer, 0, $pos)."'";
					$buffer = substr($buffer, $pos);
				}
			}
		}

		return '(' . implode(' + ', $strings) . ')';

	}

	/**
	 * Function to return an SQL datetime expression for MSSQL.
	 * used for querying a datetime addition
	 * 
	 * @param string $date, can be either 'now', literal datetime like '1973-10-14 10:30:00' or field name, e.g. '"SiteTree"."Created"'
	 * @param string $interval to be added, use the format [sign][integer] [qualifier], e.g. -1 Day, +15 minutes, +1 YEAR
	 * supported qualifiers:
	 * - years
	 * - months
	 * - days
	 * - hours
	 * - minutes
	 * - seconds
	 * This includes the singular forms as well
	 * @return string SQL datetime expression to query for a datetime (YYYY-MM-DD hh:mm:ss) which is the result of the addition
	 */
	function datetimeIntervalClause($date, $interval) {
		$trans = array(
			'year' => 'yy',
			'month' => 'mm',
			'day' => 'dd',
			'hour' => 'hh',
			'minute' => 'mi',
			'second' => 'ss',
		);

		$singularinterval = preg_replace('/(year|month|day|hour|minute|second)s/i', '$1', $interval);

		if(
			!($params = preg_match('/([-+]\d+) (\w+)/i', $singularinterval, $matches)) ||
			!isset($trans[strtolower($matches[2])])
		)  user_error('datetimeIntervalClause(): invalid interval ' . $interval, E_USER_WARNING);

		if(preg_match('/^now$/i', $date)) {
			$date = "CURRENT_TIMESTAMP";
		} else if(preg_match('/^\d{4}-\d{2}-\d{2} \d{2}:\d{2}:\d{2}$/i', $date)) {
			$date = "'$date'";
		}

		return "CONVERT(VARCHAR, DATEADD(" . $trans[strtolower($matches[2])] . ", " . (int)$matches[1] . ", $date), 120)";
	}

	/**
	 * Function to return an SQL datetime expression for MSSQL.
	 * used for querying a datetime substraction
	 * 
	 * @param string $date1, can be either 'now', literal datetime like '1973-10-14 10:30:00' or field name, e.g. '"SiteTree"."Created"'
	 * @param string $date2 to be substracted of $date1, can be either 'now', literal datetime like '1973-10-14 10:30:00' or field name, e.g. '"SiteTree"."Created"'
	 * @return string SQL datetime expression to query for the interval between $date1 and $date2 in seconds which is the result of the substraction
	 */
	function datetimeDifferenceClause($date1, $date2) {

		if(preg_match('/^now$/i', $date1)) {
			$date1 = "CURRENT_TIMESTAMP";
		} else if(preg_match('/^\d{4}-\d{2}-\d{2} \d{2}:\d{2}:\d{2}$/i', $date1)) {
			$date1 = "'$date1'";
		}

		if(preg_match('/^now$/i', $date2)) {
			$date2 = "CURRENT_TIMESTAMP";
		} else if(preg_match('/^\d{4}-\d{2}-\d{2} \d{2}:\d{2}:\d{2}$/i', $date2)) {
			$date2 = "'$date2'";
		}

		return "DATEDIFF(s, $date2, $date1)";
	}
}