<?php
/**
 * CodeIgniter
 *
 * An open source application development framework for PHP
 *
 * This content is released under the MIT License (MIT)
 *
 * Copyright (c) 2014 - 2016, 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 - 2016, 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');

/**
 * MySQLi 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_mysqli_driver extends CI_DB {

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

	/**
	 * Compression flag
	 *
	 * @var	bool
	 */
	public $compress = FALSE;

	/**
	 * DELETE hack flag
	 *
	 * Whether to use the MySQL "delete hack" which allows the number
	 * of affected rows to be shown. Uses a preg_replace when enabled,
	 * adding a bit more processing to all queries.
	 *
	 * @var	bool
	 */
	public $delete_hack = TRUE;

	/**
	 * Strict ON flag
	 *
	 * Whether we're running in strict SQL mode.
	 *
	 * @var	bool
	 */
	public $stricton;

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

	/**
	 * Identifier escape character
	 *
	 * @var	string
	 */
	protected $_escape_char = '`';

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

	/**
	 * MySQLi object
	 *
	 * Has to be preserved without being assigned to $conn_id.
	 *
	 * @var	MySQLi
	 */
	protected $_mysqli;

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

	/**
	 * Database connection
	 *
	 * @param	bool	$persistent
	 * @return	object
	 */
	public function db_connect($persistent = FALSE)
	{
		// Do we have a socket path?
		if ($this->hostname[0] === '/')
		{
			$hostname = NULL;
			$port = NULL;
			$socket = $this->hostname;
		}
		else
		{
			// Persistent connection support was added in PHP 5.3.0
			$hostname = ($persistent === TRUE && is_php('5.3'))
				? 'p:'.$this->hostname : $this->hostname;
			$port = empty($this->port) ? NULL : $this->port;
			$socket = NULL;
		}

		$client_flags = ($this->compress === TRUE) ? MYSQLI_CLIENT_COMPRESS : 0;
		$this->_mysqli = mysqli_init();

		$this->_mysqli->options(MYSQLI_OPT_CONNECT_TIMEOUT, 10);

		if (isset($this->stricton))
		{
			if ($this->stricton)
			{
				$this->_mysqli->options(MYSQLI_INIT_COMMAND, 'SET SESSION sql_mode = CONCAT(@@sql_mode, ",", "STRICT_ALL_TABLES")');
			}
			else
			{
				$this->_mysqli->options(MYSQLI_INIT_COMMAND,
					'SET SESSION sql_mode =
					REPLACE(REPLACE(REPLACE(REPLACE(REPLACE(REPLACE(
					@@sql_mode,
					"STRICT_ALL_TABLES,", ""),
					",STRICT_ALL_TABLES", ""),
					"STRICT_ALL_TABLES", ""),
					"STRICT_TRANS_TABLES,", ""),
					",STRICT_TRANS_TABLES", ""),
					"STRICT_TRANS_TABLES", "")'
				);
			}
		}

		if (is_array($this->encrypt))
		{
			$ssl = array();
			empty($this->encrypt['ssl_key'])    OR $ssl['key']    = $this->encrypt['ssl_key'];
			empty($this->encrypt['ssl_cert'])   OR $ssl['cert']   = $this->encrypt['ssl_cert'];
			empty($this->encrypt['ssl_ca'])     OR $ssl['ca']     = $this->encrypt['ssl_ca'];
			empty($this->encrypt['ssl_capath']) OR $ssl['capath'] = $this->encrypt['ssl_capath'];
			empty($this->encrypt['ssl_cipher']) OR $ssl['cipher'] = $this->encrypt['ssl_cipher'];

			if ( ! empty($ssl))
			{
				if (isset($this->encrypt['ssl_verify']))
				{
					if ($this->encrypt['ssl_verify'])
					{
						defined('MYSQLI_OPT_SSL_VERIFY_SERVER_CERT') && $this->_mysqli->options(MYSQLI_OPT_SSL_VERIFY_SERVER_CERT, TRUE);
					}
					// Apparently (when it exists), setting MYSQLI_OPT_SSL_VERIFY_SERVER_CERT
					// to FALSE didn't do anything, so PHP 5.6.16 introduced yet another
					// constant ...
					//
					// https://secure.php.net/ChangeLog-5.php#5.6.16
					// https://bugs.php.net/bug.php?id=68344
					elseif (defined('MYSQLI_CLIENT_SSL_DONT_VERIFY_SERVER_CERT'))
					{
						$this->_mysqli->options(MYSQLI_CLIENT_SSL_DONT_VERIFY_SERVER_CERT, TRUE);
					}
				}

				$client_flags |= MYSQLI_CLIENT_SSL;
				$this->_mysqli->ssl_set(
					isset($ssl['key'])    ? $ssl['key']    : NULL,
					isset($ssl['cert'])   ? $ssl['cert']   : NULL,
					isset($ssl['ca'])     ? $ssl['ca']     : NULL,
					isset($ssl['capath']) ? $ssl['capath'] : NULL,
					isset($ssl['cipher']) ? $ssl['cipher'] : NULL
				);
			}
		}

		if ($this->_mysqli->real_connect($hostname, $this->username, $this->password, $this->database, $port, $socket, $client_flags))
		{
			// Prior to version 5.7.3, MySQL silently downgrades to an unencrypted connection if SSL setup fails
			if (
				($client_flags & MYSQLI_CLIENT_SSL)
				&& version_compare($this->_mysqli->client_info, '5.7.3', '<=')
				&& empty($this->_mysqli->query("SHOW STATUS LIKE 'ssl_cipher'")->fetch_object()->Value)
			)
			{
				$this->_mysqli->close();
				$message = 'MySQLi was configured for an SSL connection, but got an unencrypted connection instead!';
				log_message('error', $message);
				return ($this->db->db_debug) ? $this->db->display_error($message, '', TRUE) : FALSE;
			}

			if ( ! $this->_mysqli->set_charset($this->char_set))
			{
				log_message('error', "Database: Unable to set the configured connection charset ('{$this->char_set}').");
				$this->_mysqli->close();
				return ($this->db->db_debug) ? $this->display_error('db_unable_to_set_charset', $this->char_set) : FALSE;
			}

			return $this->_mysqli;
		}

		return FALSE;
	}

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

	/**
	 * Reconnect
	 *
	 * Keep / reestablish the db connection if no queries have been
	 * sent for a length of time exceeding the server's idle timeout
	 *
	 * @return	void
	 */
	public function reconnect()
	{
		if ($this->conn_id !== FALSE && $this->conn_id->ping() === FALSE)
		{
			$this->conn_id = FALSE;
		}
	}

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

	/**
	 * Select the database
	 *
	 * @param	string	$database
	 * @return	bool
	 */
	public function db_select($database = '')
	{
		if ($database === '')
		{
			$database = $this->database;
		}

		if ($this->conn_id->select_db($database))
		{
			$this->database = $database;
			$this->data_cache = array();
			return TRUE;
		}

		return FALSE;
	}

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

	/**
	 * Database version number
	 *
	 * @return	string
	 */
	public function version()
	{
		if (isset($this->data_cache['version']))
		{
			return $this->data_cache['version'];
		}

		return $this->data_cache['version'] = $this->conn_id->server_info;
	}

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

	/**
	 * Execute the query
	 *
	 * @param	string	$sql	an SQL query
	 * @return	mixed
	 */
	protected function _execute($sql)
	{
		return $this->conn_id->query($this->_prep_query($sql));
	}

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

	/**
	 * Prep the query
	 *
	 * If needed, each database adapter can prep the query string
	 *
	 * @param	string	$sql	an SQL query
	 * @return	string
	 */
	protected function _prep_query($sql)
	{
		// mysqli_affected_rows() returns 0 for "DELETE FROM TABLE" queries. This hack
		// modifies the query so that it a proper number of affected rows is returned.
		if ($this->delete_hack === TRUE && preg_match('/^\s*DELETE\s+FROM\s+(\S+)\s*$/i', $sql))
		{
			return trim($sql).' WHERE 1=1';
		}

		return $sql;
	}

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

	/**
	 * Begin Transaction
	 *
	 * @return	bool
	 */
	protected function _trans_begin()
	{
		$this->conn_id->autocommit(FALSE);
		return is_php('5.5')
			? $this->conn_id->begin_transaction()
			: $this->simple_query('START TRANSACTION'); // can also be BEGIN or BEGIN WORK
	}

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

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

		return FALSE;
	}

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

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

		return FALSE;
	}

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

	/**
	 * Platform-dependant string escape
	 *
	 * @param	string
	 * @return	string
	 */
	protected function _escape_str($str)
	{
		return $this->conn_id->real_escape_string($str);
	}

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

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

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

	/**
	 * Insert ID
	 *
	 * @return	int
	 */
	public function insert_id()
	{
		return $this->conn_id->insert_id;
	}

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

	/**
	 * List 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)
	{
		$sql = 'SHOW TABLES FROM '.$this->escape_identifiers($this->database);

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

		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 '.$this->protect_identifiers($table, TRUE, NULL, FALSE);
	}

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

	/**
	 * Returns an object with field data
	 *
	 * @param	string	$table
	 * @return	array
	 */
	public function field_data($table)
	{
		if (($query = $this->query('SHOW COLUMNS FROM '.$this->protect_identifiers($table, TRUE, NULL, FALSE))) === 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]->Field;

			sscanf($query[$i]->Type, '%[a-z](%d)',
				$retval[$i]->type,
				$retval[$i]->max_length
			);

			$retval[$i]->default		= $query[$i]->Default;
			$retval[$i]->primary_key	= (int) ($query[$i]->Key === 'PRI');
		}

		return $retval;
	}

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

	/**
	 * Error
	 *
	 * Returns an array containing code and message of the last
	 * database error that has occurred.
	 *
	 * @return	array
	 */
	public function error()
	{
		if ( ! empty($this->_mysqli->connect_errno))
		{
			return array(
				'code' => $this->_mysqli->connect_errno,
				'message' => is_php('5.2.9') ? $this->_mysqli->connect_error : mysqli_connect_error()
			);
		}

		return array('code' => $this->conn_id->errno, 'message' => $this->conn_id->error);
	}

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

	/**
	 * FROM tables
	 *
	 * Groups tables in FROM clauses if needed, so there is no confusion
	 * about operator precedence.
	 *
	 * @return	string
	 */
	protected function _from_tables()
	{
		if ( ! empty($this->qb_join) && count($this->qb_from) > 1)
		{
			return '('.implode(', ', $this->qb_from).')';
		}

		return implode(', ', $this->qb_from);
	}

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

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

}