<?php
/**
* CodeIgniter
*
* An open source application development framework for PHP
*
* This content is released under the MIT License (MIT)
*
* Copyright (c) 2014 - 2015, British Columbia Institute of Technology
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*
* @package CodeIgniter
* @author EllisLab Dev Team
* @copyright Copyright (c) 2008 - 2014, EllisLab, Inc. (http://ellislab.com/)
* @copyright Copyright (c) 2014 - 2015, British Columbia Institute of Technology (http://bcit.ca/)
* @license http://opensource.org/licenses/MIT MIT License
* @link http://codeigniter.com
* @since Version 3.0.0
* @filesource
*/
defined('BASEPATH') OR exit('No direct script access allowed');

/**
* PDO DBLIB Database Adapter Class
*
* Note: _DB is an extender class that the app controller
* creates dynamically based on whether the query builder
* class is being used or not.
*
* @package CodeIgniter
* @subpackage Drivers
* @category Database
* @author EllisLab Dev Team
* @link http://codeigniter.com/user_guide/database/
*/
class CI_DB_pdo_dblib_driver extends CI_DB_pdo_driver {

/**
* Sub-driver
*
* @var string
*/
public $subdriver = 'dblib';

// --------------------------------------------------------------------

/**
* ORDER BY random keyword
*
* @var array
*/
protected $_random_keyword = array('NEWID()', 'RAND(%d)');

/**
* Quoted identifier flag
*
* Whether to use SQL-92 standard quoted identifier
* (double quotes) or brackets for identifier escaping.
*
* @var bool
*/
protected $_quoted_identifier;

// --------------------------------------------------------------------

/**
* Class constructor
*
* Builds the DSN if not already set.
*
* @param array $params
* @return void
*/
public function __construct($params)
{
parent::__construct($params);

if (empty($this->dsn))
{
$this->dsn = $params['subdriver'].':host='.(empty($this->hostname) ? '127.0.0.1' : $this->hostname);

if ( ! empty($this->port))
{
$this->dsn .= (DIRECTORY_SEPARATOR === '\\' ? ',' : ':').$this->port;
}

empty($this->database) OR $this->dsn .= ';dbname='.$this->database;
empty($this->char_set) OR $this->dsn .= ';charset='.$this->char_set;
empty($this->appname) OR $this->dsn .= ';appname='.$this->appname;
}
else
{
if ( ! empty($this->char_set) && strpos($this->dsn, 'charset=', 6) === FALSE)
{
$this->dsn .= ';charset='.$this->char_set;
}

$this->subdriver = 'dblib';
}
}

// --------------------------------------------------------------------

/**
* Database connection
*
* @param bool $persistent
* @return object
*/
public function db_connect($persistent = FALSE)
{
$this->conn_id = parent::db_connect($persistent);

if ( ! is_object($this->conn_id))
{
return $this->conn_id;
}

// Determine how identifiers are escaped
$query = $this->query('SELECT CASE WHEN (@@OPTIONS | 256) = @@OPTIONS THEN 1 ELSE 0 END AS qi');
$query = $query->row_array();
$this->_quoted_identifier = empty($query) ? FALSE : (bool) $query['qi'];
$this->_escape_char = ($this->_quoted_identifier) ? '"' : array('[', ']');

return $this->conn_id;
}

// --------------------------------------------------------------------

/**
* Show table query
*
* Generates a platform-specific query string so that the table names can be fetched
*
* @param bool $prefix_limit
* @return string
*/
protected function _list_tables($prefix_limit = FALSE)
{
$sql = 'SELECT '.$this->escape_identifiers('name')
.' FROM '.$this->escape_identifiers('sysobjects')
.' WHERE '.$this->escape_identifiers('type')." = 'U'";

if ($prefix_limit === TRUE && $this->dbprefix !== '')
{
$sql .= ' AND '.$this->escape_identifiers('name')." LIKE '".$this->escape_like_str($this->dbprefix)."%' "
.sprintf($this->_like_escape_str, $this->_like_escape_chr);
}

return $sql.' ORDER BY '.$this->escape_identifiers('name');
}

// --------------------------------------------------------------------

/**
* Show column query
*
* Generates a platform-specific query string so that the column names can be fetched
*
* @param string $table
* @return string
*/
protected function _list_columns($table = '')
{
return 'SELECT COLUMN_NAME
FROM INFORMATION_SCHEMA.Columns
WHERE UPPER(TABLE_NAME) = '.$this->escape(strtoupper($table));
}

// --------------------------------------------------------------------

/**
* Returns an object with field data
*
* @param string $table
* @return array
*/
public function field_data($table)
{
$sql = 'SELECT COLUMN_NAME, DATA_TYPE, CHARACTER_MAXIMUM_LENGTH, NUMERIC_PRECISION, COLUMN_DEFAULT
FROM INFORMATION_SCHEMA.Columns
WHERE UPPER(TABLE_NAME) = '.$this->escape(strtoupper($table));

if (($query = $this->query($sql)) === FALSE)
{
return FALSE;
}
$query = $query->result_object();

$retval = array();
for ($i = 0, $c = count($query); $i < $c; $i++)
{
$retval[$i] = new stdClass();
$retval[$i]->name = $query[$i]->COLUMN_NAME;
$retval[$i]->type = $query[$i]->DATA_TYPE;
$retval[$i]->max_length = ($query[$i]->CHARACTER_MAXIMUM_LENGTH > 0) ? $query[$i]->CHARACTER_MAXIMUM_LENGTH : $query[$i]->NUMERIC_PRECISION;
$retval[$i]->default = $query[$i]->COLUMN_DEFAULT;
}

return $retval;
}

// --------------------------------------------------------------------

/**
* Update statement
*
* Generates a platform-specific update string from the supplied data
*
* @param string $table
* @param array $values
* @return string
*/
protected function _update($table, $values)
{
$this->qb_limit = FALSE;
$this->qb_orderby = array();
return parent::_update($table, $values);
}

// --------------------------------------------------------------------

/**
* Delete statement
*
* Generates a platform-specific delete string from the supplied data
*
* @param string $table
* @return string
*/
protected function _delete($table)
{
if ($this->qb_limit)
{
return 'WITH ci_delete AS (SELECT TOP '.$this->qb_limit.' * FROM '.$table.$this->_compile_wh('qb_where').') DELETE FROM ci_delete';
}

return parent::_delete($table);
}

// --------------------------------------------------------------------

/**
* LIMIT
*
* Generates a platform-specific LIMIT clause
*
* @param string $sql SQL Query
* @return string
*/
protected function _limit($sql)
{
$limit = $this->qb_offset + $this->qb_limit;

// As of SQL Server 2005 (9.0.*) ROW_NUMBER() is supported,
// however an ORDER BY clause is required for it to work
if (version_compare($this->version(), '9', '>=') && $this->qb_offset && ! empty($this->qb_orderby))
{
$orderby = $this->_compile_order_by();

// We have to strip the ORDER BY clause
$sql = trim(substr($sql, 0, strrpos($sql, $orderby)));

// Get the fields to select from our subquery, so that we can avoid CI_rownum appearing in the actual results
if (count($this->qb_select) === 0)
{
$select = '*'; // Inevitable
}
else
{
// Use only field names and their aliases, everything else is out of our scope.
$select = array();
$field_regexp = ($this->_quoted_identifier)
? '("[^\"]+")' : '(\[[^\]]+\])';
for ($i = 0, $c = count($this->qb_select); $i < $c; $i++)
{
$select[] = preg_match('/(?:\s|\.)'.$field_regexp.'$/i', $this->qb_select[$i], $m)
? $m[1] : $this->qb_select[$i];
}
$select = implode(', ', $select);
}

return 'SELECT '.$select." FROM (\n\n"
.preg_replace('/^(SELECT( DISTINCT)?)/i', '\\1 ROW_NUMBER() OVER('.trim($orderby).') AS '.$this->escape_identifiers('CI_rownum').', ', $sql)
."\n\n) ".$this->escape_identifiers('CI_subquery')
."\nWHERE ".$this->escape_identifiers('CI_rownum').' BETWEEN '.($this->qb_offset + 1).' AND '.$limit;
}

return preg_replace('/(^\SELECT (DISTINCT)?)/i','\\1 TOP '.$limit.' ', $sql);
}

// --------------------------------------------------------------------

/**
* Insert batch statement
*
* Generates a platform-specific insert string from the supplied data.
*
* @param string $table Table name
* @param array $keys INSERT keys
* @param array $values INSERT values
* @return string|bool
*/
protected function _insert_batch($table, $keys, $values)
{
// Multiple-value inserts are only supported as of SQL Server 2008
if (version_compare($this->version(), '10', '>='))
{
return parent::_insert_batch($table, $keys, $values);
}

return ($this->db->db_debug) ? $this->db->display_error('db_unsupported_feature') : FALSE;
}

}