<?php
/**
 * CodeIgniter
 *
 * An open source application development framework for PHP
 *
 * This content is released under the MIT License (MIT)
 *
 * Copyright (c) 2014 - 2017, 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. (https://ellislab.com/)
 * @copyright	Copyright (c) 2014 - 2017, British Columbia Institute of Technology (http://bcit.ca/)
 * @license	http://opensource.org/licenses/MIT	MIT License
 * @link	https://codeigniter.com
 * @since	Version 1.3.0
 * @filesource
 */
defined('BASEPATH') OR exit('No direct script access allowed');

/**
 * ODBC 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		https://codeigniter.com/user_guide/database/
 */
class CI_DB_odbc_driver extends CI_DB_driver {

	/**
	 * Database driver
	 *
	 * @var	string
	 */
	public $dbdriver = 'odbc';

	/**
	 * Database schema
	 *
	 * @var	string
	 */
	public $schema = 'public';

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

	/**
	 * Identifier escape character
	 *
	 * Must be empty for ODBC.
	 *
	 * @var	string
	 */
	protected $_escape_char = '';

	/**
	 * ESCAPE statement string
	 *
	 * @var	string
	 */
	protected $_like_escape_str = " {escape '%s'} ";

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

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

	/**
	 * ODBC result ID resource returned from odbc_prepare()
	 *
	 * @var	resource
	 */
	private $odbc_result;

	/**
	 * Values to use with odbc_execute() for prepared statements
	 *
	 * @var	array
	 */
	private $binds = array();

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

	/**
	 * Class constructor
	 *
	 * @param	array	$params
	 * @return	void
	 */
	public function __construct($params)
	{
		parent::__construct($params);

		// Legacy support for DSN in the hostname field
		if (empty($this->dsn))
		{
			$this->dsn = $this->hostname;
		}
	}

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

	/**
	 * Non-persistent database connection
	 *
	 * @param	bool	$persistent
	 * @return	resource
	 */
	public function db_connect($persistent = FALSE)
	{
		return ($persistent === TRUE)
			? odbc_pconnect($this->dsn, $this->username, $this->password)
			: odbc_connect($this->dsn, $this->username, $this->password);
	}

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

	/**
	 * Compile Bindings
	 *
	 * @param	string	$sql	SQL statement
	 * @param	array	$binds	An array of values to bind
	 * @return	string
	 */
	public function compile_binds($sql, $binds)
	{
		if (empty($binds) OR empty($this->bind_marker) OR strpos($sql, $this->bind_marker) === FALSE)
		{
			return $sql;
		}
		elseif ( ! is_array($binds))
		{
			$binds = array($binds);
			$bind_count = 1;
		}
		else
		{
			// Make sure we're using numeric keys
			$binds = array_values($binds);
			$bind_count = count($binds);
		}

		// We'll need the marker length later
		$ml = strlen($this->bind_marker);

		// Make sure not to replace a chunk inside a string that happens to match the bind marker
		if ($c = preg_match_all("/'[^']*'|\"[^\"]*\"/i", $sql, $matches))
		{
			$c = preg_match_all('/'.preg_quote($this->bind_marker, '/').'/i',
				str_replace($matches[0],
					str_replace($this->bind_marker, str_repeat(' ', $ml), $matches[0]),
					$sql, $c),
				$matches, PREG_OFFSET_CAPTURE);

			// Bind values' count must match the count of markers in the query
			if ($bind_count !== $c)
			{
				return $sql;
			}
		}
		elseif (($c = preg_match_all('/'.preg_quote($this->bind_marker, '/').'/i', $sql, $matches, PREG_OFFSET_CAPTURE)) !== $bind_count)
		{
			return $sql;
		}

		if ($this->bind_marker !== '?')
		{
			do
			{
				$c--;
				$sql = substr_replace($sql, '?', $matches[0][$c][1], $ml);
			}
			while ($c !== 0);
		}

		if (FALSE !== ($this->odbc_result = odbc_prepare($this->conn_id, $sql)))
		{
			$this->binds = array_values($binds);
		}

		return $sql;
	}

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

	/**
	 * Execute the query
	 *
	 * @param	string	$sql	an SQL query
	 * @return	resource
	 */
	protected function _execute($sql)
	{
		if ( ! isset($this->odbc_result))
		{
			return odbc_exec($this->conn_id, $sql);
		}
		elseif ($this->odbc_result === FALSE)
		{
			return FALSE;
		}

		if (TRUE === ($success = odbc_execute($this->odbc_result, $this->binds)))
		{
			// For queries that return result sets, return the result_id resource on success
			$this->is_write_type($sql) OR $success = $this->odbc_result;
		}

		$this->odbc_result = NULL;
		$this->binds       = array();

		return $success;
	}

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

	/**
	 * Begin Transaction
	 *
	 * @return	bool
	 */
	protected function _trans_begin()
	{
		return odbc_autocommit($this->conn_id, FALSE);
	}

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

	/**
	 * Commit Transaction
	 *
	 * @return	bool
	 */
	protected function _trans_commit()
	{
		if (odbc_commit($this->conn_id))
		{
			odbc_autocommit($this->conn_id, TRUE);
			return TRUE;
		}

		return FALSE;
	}

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

	/**
	 * Rollback Transaction
	 *
	 * @return	bool
	 */
	protected function _trans_rollback()
	{
		if (odbc_rollback($this->conn_id))
		{
			odbc_autocommit($this->conn_id, TRUE);
			return TRUE;
		}

		return FALSE;
	}

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

	/**
	 * Determines if a query is a "write" type.
	 *
	 * @param	string	An SQL query string
	 * @return	bool
	 */
	public function is_write_type($sql)
	{
		if (preg_match('#^(INSERT|UPDATE).*RETURNING\s.+(\,\s?.+)*$#is', $sql))
		{
			return FALSE;
		}

		return parent::is_write_type($sql);
	}

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

	/**
	 * Platform-dependant string escape
	 *
	 * @param	string
	 * @return	string
	 */
	protected function _escape_str($str)
	{
		$this->db->display_error('db_unsupported_feature');
	}

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

	/**
	 * Affected Rows
	 *
	 * @return	int
	 */
	public function affected_rows()
	{
		return odbc_num_rows($this->result_id);
	}

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

	/**
	 * Insert ID
	 *
	 * @return	bool
	 */
	public function insert_id()
	{
		return ($this->db->db_debug) ? $this->db->display_error('db_unsupported_feature') : FALSE;
	}

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

	/**
	 * 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)
	{
		$sql = "SELECT table_name FROM information_schema.tables WHERE table_schema = '".$this->schema."'";

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

		return $sql;
	}

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

	/**
	 * 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 'SHOW COLUMNS FROM '.$table;
	}

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

	/**
	 * Field data query
	 *
	 * Generates a platform-specific query so that the column data can be retrieved
	 *
	 * @param	string	$table
	 * @return	string
	 */
	protected function _field_data($table)
	{
		return 'SELECT TOP 1 FROM '.$table;
	}

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

	/**
	 * Error
	 *
	 * Returns an array containing code and message of the last
	 * database error that has occured.
	 *
	 * @return	array
	 */
	public function error()
	{
		return array('code' => odbc_error($this->conn_id), 'message' => odbc_errormsg($this->conn_id));
	}

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

	/**
	 * Close DB Connection
	 *
	 * @return	void
	 */
	protected function _close()
	{
		odbc_close($this->conn_id);
	}
}
