<?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 1.0.0
 * @filesource
 */
defined('BASEPATH') OR exit('No direct script access allowed');

/**
 * MySQL 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_mysql_driver extends CI_DB {

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

    /**
     * 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 = '`';

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

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

        if (!empty($this->port)) {
            $this->hostname .= ':' . $this->port;
        }
    }

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

    /**
     * Non-persistent database connection
     *
     * @param	bool	$persistent
     * @return	resource
     */
    public function db_connect($persistent = FALSE) {
        $client_flags = ($this->compress === FALSE) ? 0 : MYSQL_CLIENT_COMPRESS;

        if ($this->encrypt === TRUE) {
            $client_flags = $client_flags | MYSQL_CLIENT_SSL;
        }

        // Error suppression is necessary mostly due to PHP 5.5+ issuing E_DEPRECATED messages
        $this->conn_id = ($persistent === TRUE) ? mysql_pconnect($this->hostname, $this->username, $this->password, $client_flags) : mysql_connect($this->hostname, $this->username, $this->password, TRUE, $client_flags);

        // ----------------------------------------------------------------
        // Select the DB... assuming a database name is specified in the config file
        if ($this->database !== '' && !$this->db_select()) {
            log_message('error', 'Unable to select database: ' . $this->database);

            return ($this->db_debug === TRUE) ? $this->display_error('db_unable_to_select', $this->database) : FALSE;
        }

        if (isset($this->stricton) && is_resource($this->conn_id)) {
            if ($this->stricton) {
                $this->simple_query('SET SESSION sql_mode = CONCAT(@@sql_mode, ",", "STRICT_ALL_TABLES")');
            } else {
                $this->simple_query(
                        '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", "")'
                );
            }
        }

        return $this->conn_id;
    }

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

    /**
     * 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 (mysql_ping($this->conn_id) === FALSE) {
            $this->conn_id = FALSE;
        }
    }

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

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

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

        return FALSE;
    }

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

    /**
     * Set client character set
     *
     * @param	string	$charset
     * @return	bool
     */
    protected function _db_set_charset($charset) {
        return mysql_set_charset($charset, $this->conn_id);
    }

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

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

        if (!$this->conn_id OR ( $version = mysql_get_server_info($this->conn_id)) === FALSE) {
            return FALSE;
        }

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

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

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

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

    /**
     * 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) {
        // mysql_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->simple_query('SET AUTOCOMMIT=0');
        return $this->simple_query('START TRANSACTION'); // can also be BEGIN or BEGIN WORK
    }

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

    /**
     * Commit Transaction
     *
     * @return	bool
     */
    protected function _trans_commit() {
        if ($this->simple_query('COMMIT')) {
            $this->simple_query('SET AUTOCOMMIT=1');
            return TRUE;
        }

        return FALSE;
    }

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

    /**
     * Rollback Transaction
     *
     * @return	bool
     */
    protected function _trans_rollback() {
        if ($this->simple_query('ROLLBACK')) {
            $this->simple_query('SET AUTOCOMMIT=1');
            return TRUE;
        }

        return FALSE;
    }

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

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

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

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

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

    /**
     * Insert ID
     *
     * @return	int
     */
    public function insert_id() {
        return mysql_insert_id($this->conn_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() {
        return array('code' => mysql_errno($this->conn_id), 'message' => mysql_error($this->conn_id));
    }

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

    /**
     * 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() {
        // Error suppression to avoid annoying E_WARNINGs in cases
        // where the connection has already been closed for some reason.
        @mysql_close($this->conn_id);
    }

}
