<?php if ( ! defined('BASEPATH')) exit('No direct script access allowed');
/**
 * CodeIgniter
 *
 * An open source application development framework for PHP 5.2.4 or newer
 *
 * NOTICE OF LICENSE
 *
 * Licensed under the Open Software License version 3.0
 *
 * This source file is subject to the Open Software License (OSL 3.0) that is
 * bundled with this package in the files license.txt / license.rst.  It is
 * also available through the world wide web at this URL:
 * http://opensource.org/licenses/OSL-3.0
 * If you did not receive a copy of the license and are unable to obtain it
 * through the world wide web, please send an email to
 * licensing@ellislab.com so we can send you a copy immediately.
 *
 * @package     CodeIgniter
 * @author      EllisLab Dev Team
 * @copyright   Copyright (c) 2008 - 2012, EllisLab, Inc. (http://ellislab.com/)
 * @license     http://opensource.org/licenses/OSL-3.0 Open Software License (OSL 3.0)
 * @link        http://codeigniter.com
 * @since       Version 1.0
 * @filesource
 */

/**
 * Database Driver Class
 *
 * This is the platform-independent base DB implementation class.
 * This class will not be called directly. Rather, the adapter
 * class for the specific database will extend and instantiate it.
 *
 * @package     CodeIgniter
 * @subpackage  Drivers
 * @category    Database
 * @author      EllisLab Dev Team
 * @link        http://codeigniter.com/user_guide/database/
 */
abstract class CI_DB_driver {

    public $dsn;
    public $username;
    public $password;
    public $hostname;
    public $database;
    public $dbdriver        = 'mysqli';
    public $subdriver;
    public $dbprefix        = '';
    public $char_set        = 'utf8';
    public $dbcollat        = 'utf8_general_ci';
    public $autoinit        = TRUE; // Whether to automatically initialize the DB
    public $compress        = TRUE;
    public $swap_pre        = '';
    public $port            = '';
    public $pconnect        = FALSE;
    public $conn_id         = FALSE;
    public $result_id       = FALSE;
    public $db_debug        = FALSE;
    public $benchmark       = 0;
    public $query_count     = 0;
    public $bind_marker     = '?';
    public $save_queries        = TRUE;
    public $queries         = array();
    public $query_times     = array();
    public $data_cache      = array();

    public $trans_enabled       = TRUE;
    public $trans_strict        = TRUE;
    protected $_trans_depth     = 0;
    protected $_trans_status    = TRUE; // Used with transactions to determine if a rollback should occur

    public $cache_on        = FALSE;
    public $cachedir        = '';
    public $cache_autodel       = FALSE;
    public $CACHE; // The cache class object

    protected $_protect_identifiers     = TRUE;
    protected $_reserved_identifiers    = array('*'); // Identifiers that should NOT be escaped

    // clause and character used for LIKE escape sequences
    protected $_like_escape_str = " ESCAPE '%s' ";
    protected $_like_escape_chr = '!';

    /**
     * The syntax to count rows is slightly different across different
     * database engines, so this string appears in each driver and is
     * used for the count_all() and count_all_results() functions.
     */
    protected $_count_string = 'SELECT COUNT(*) AS ';

    /**
     * Constructor
     *
     * @param   array
     * @return  void
     */
    public function __construct($params)
    {
        if (is_array($params))
        {
            foreach ($params as $key => $val)
            {
                $this->$key = $val;
            }
        }

        log_message('debug', 'Database Driver Class Initialized');
    }

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

    /**
     * Initialize Database Settings
     *
     * @return  bool
     */
    public function initialize()
    {
        /* If an established connection is available, then there's
         * no need to connect and select the database.
         *
         * Depending on the database driver, conn_id can be either
         * boolean TRUE, a resource or an object.
         */
        if ($this->conn_id)
        {
            return TRUE;
        }

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

        // Connect to the database and set the connection ID
        $this->conn_id = ($this->pconnect === FALSE) ? $this->db_connect() : $this->db_pconnect();

        // No connection resource? Check if there is a failover else throw an error
        if ( ! $this->conn_id)
        {
            // Check if there is a failover set
            if ( ! empty($this->failover) && is_array($this->failover))
            {
                // Go over all the failovers
                foreach ($this->failover as $failover)
                {
                    // Replace the current settings with those of the failover
                    foreach ($failover as $key => $val)
                    {
                        $this->$key = $val;
                    }

                    // Try to connect
                    $this->conn_id = ($this->pconnect === FALSE) ? $this->db_connect() : $this->db_pconnect();

                    // If a connection is made break the foreach loop
                    if ($this->conn_id)
                    {
                        break;
                    }
                }
            }

            // We still don't have a connection?
            if ( ! $this->conn_id)
            {
                log_message('error', 'Unable to connect to the database');

                if ($this->db_debug)
                {
                    $this->display_error('db_unable_to_connect');
                }
                return FALSE;
            }
        }

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

        // 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);

            if ($this->db_debug)
            {
                $this->display_error('db_unable_to_select', $this->database);
            }
            return FALSE;
        }

        // Now we set the character set and that's all
        return $this->db_set_charset($this->char_set);
    }

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

    /**
     * Reconnect
     *
     * Keep / reestablish the db connection if no queries have been
     * sent for a length of time exceeding the server's idle timeout.
     *
     * This is just a dummy method to allow drivers without such
     * functionality to not declare it, while others will override it.
     *
     * @return      void
     */
    public function reconnect()
    {
    }

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

    /**
     * Select database
     *
     * This is just a dummy method to allow drivers without such
     * functionality to not declare it, while others will override it.
     *
     * @return      bool
     */
    public function db_select()
    {
        return TRUE;
    }

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

    /**
     * Set client character set
     *
     * @param   string
     * @return  bool
     */
    public function db_set_charset($charset)
    {
        if (method_exists($this, '_db_set_charset') && ! $this->_db_set_charset($charset))
        {
            log_message('error', 'Unable to set database connection charset: '.$charset);

            if ($this->db_debug)
            {
                $this->display_error('db_unable_to_set_charset', $charset);
            }

            return FALSE;
        }

        return TRUE;
    }

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

    /**
     * The name of the platform in use (mysql, mssql, etc...)
     *
     * @return  string
     */
    public function platform()
    {
        return $this->dbdriver;
    }

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

    /**
     * Database version number
     *
     * Returns a string containing the version of the database being used.
     * Most drivers will override this method.
     *
     * @return  string
     */
    public function version()
    {
        if (isset($this->data_cache['version']))
        {
            return $this->data_cache['version'];
        }

        if (FALSE === ($sql = $this->_version()))
        {
            return ($this->db_debug) ? $this->display_error('db_unsupported_function') : FALSE;
        }

        $query = $this->query($sql);
        $query = $query->row();
        return $this->data_cache['version'] = $query->ver;
    }

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

    /**
     * Version number query string
     *
     * @return  string
     */
    protected function _version()
    {
        return 'SELECT VERSION() AS ver';
    }

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

    /**
     * Execute the query
     *
     * Accepts an SQL string as input and returns a result object upon
     * successful execution of a "read" type query. Returns boolean TRUE
     * upon successful execution of a "write" type query. Returns boolean
     * FALSE upon failure, and if the $db_debug variable is set to TRUE
     * will raise an error.
     *
     * @param   string  An SQL query string
     * @param   array   An array of binding data
     * @return  mixed
     */
    public function query($sql, $binds = FALSE, $return_object = NULL)
    {
        if ($sql === '')
        {
            log_message('error', 'Invalid query: '.$sql);

            return ($this->db_debug) ? $this->display_error('db_invalid_query') : FALSE;
        }
        elseif ( ! is_bool($return_object))
        {
            $return_object = ! $this->is_write_type($sql);
        }

        // Verify table prefix and replace if necessary
        if ($this->dbprefix !== '' && $this->swap_pre !== '' && $this->dbprefix !== $this->swap_pre)
        {
            $sql = preg_replace('/(\W)'.$this->swap_pre.'(\S+?)/', '\\1'.$this->dbprefix.'\\2', $sql);
        }

        // Compile binds if needed
        if ($binds !== FALSE)
        {
            $sql = $this->compile_binds($sql, $binds);
        }

        // Is query caching enabled? If the query is a "read type"
        // we will load the caching class and return the previously
        // cached query if it exists
        if ($this->cache_on === TRUE && $return_object === TRUE && $this->_cache_init())
        {
            $this->load_rdriver();
            if (FALSE !== ($cache = $this->CACHE->read($sql)))
            {
                return $cache;
            }
        }

        // Save the query for debugging
        if ($this->save_queries === TRUE)
        {
            $this->queries[] = $sql;
        }

        // Start the Query Timer
        $time_start = microtime(TRUE);

        // Run the Query
        if (FALSE === ($this->result_id = $this->simple_query($sql)))
        {
            if ($this->save_queries === TRUE)
            {
                $this->query_times[] = 0;
            }

            // This will trigger a rollback if transactions are being used
            $this->_trans_status = FALSE;

            // Grab the error now, as we might run some additional queries before displaying the error
            $error = $this->error();

            // Log errors
            log_message('error', 'Query error: '.$error['message'].' - Invalid query: '.$sql);

            if ($this->db_debug)
            {
                // We call this function in order to roll-back queries
                // if transactions are enabled. If we don't call this here
                // the error message will trigger an exit, causing the
                // transactions to remain in limbo.
                $this->trans_complete();

                // Display errors
                return $this->display_error(array('Error Number: '.$error['code'], $error['message'], $sql));
            }

            return FALSE;
        }

        // Stop and aggregate the query time results
        $time_end = microtime(TRUE);
        $this->benchmark += $time_end - $time_start;

        if ($this->save_queries === TRUE)
        {
            $this->query_times[] = $time_end - $time_start;
        }

        // Increment the query counter
        $this->query_count++;

        // Will we have a result object instantiated? If not - we'll simply return TRUE
        if ($return_object !== TRUE)
        {
            // If caching is enabled we'll auto-cleanup any existing files related to this particular URI
            if ($this->cache_on === TRUE && $this->cache_autodel === TRUE && $this->_cache_init())
            {
                $this->CACHE->delete();
            }

            return TRUE;
        }

        // Return TRUE if we don't need to create a result object
        if ($return_object !== TRUE)
        {
            return TRUE;
        }

        // Load and instantiate the result driver
        $driver     = $this->load_rdriver();
        $RES        = new $driver($this);

        // Is query caching enabled? If so, we'll serialize the
        // result object and save it to a cache file.
        if ($this->cache_on === TRUE && $this->_cache_init())
        {
            // We'll create a new instance of the result object
            // only without the platform specific driver since
            // we can't use it with cached data (the query result
            // resource ID won't be any good once we've cached the
            // result object, so we'll have to compile the data
            // and save it)
            $CR = new CI_DB_result();
            $CR->result_object  = $RES->result_object();
            $CR->result_array   = $RES->result_array();
            $CR->num_rows       = $RES->num_rows();

            // Reset these since cached objects can not utilize resource IDs.
            $CR->conn_id        = NULL;
            $CR->result_id      = NULL;

            $this->CACHE->write($sql, $CR);
        }

        return $RES;
    }

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

    /**
     * Load the result drivers
     *
     * @return  string  the name of the result class
     */
    public function load_rdriver()
    {
        $driver = 'CI_DB_'.$this->dbdriver.'_result';

        if ( ! class_exists($driver))
        {
            include_once(BASEPATH.'database/DB_result.php');
            include_once(BASEPATH.'database/drivers/'.$this->dbdriver.'/'.$this->dbdriver.'_result.php');
        }

        return $driver;
    }

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

    /**
     * Simple Query
     * This is a simplified version of the query() function. Internally
     * we only use it when running transaction commands since they do
     * not require all the features of the main query() function.
     *
     * @param   string  the sql query
     * @return  mixed
     */
    public function simple_query($sql)
    {
        if ( ! $this->conn_id)
        {
            $this->initialize();
        }

        return $this->_execute($sql);
    }

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

    /**
     * Disable Transactions
     * This permits transactions to be disabled at run-time.
     *
     * @return  void
     */
    public function trans_off()
    {
        $this->trans_enabled = FALSE;
    }

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

    /**
     * Enable/disable Transaction Strict Mode
     * When strict mode is enabled, if you are running multiple groups of
     * transactions, if one group fails all groups will be rolled back.
     * If strict mode is disabled, each group is treated autonomously, meaning
     * a failure of one group will not affect any others
     *
     * @return  void
     */
    public function trans_strict($mode = TRUE)
    {
        $this->trans_strict = is_bool($mode) ? $mode : TRUE;
    }

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

    /**
     * Start Transaction
     *
     * @return  void
     */
    public function trans_start($test_mode = FALSE)
    {
        if ( ! $this->trans_enabled)
        {
            return FALSE;
        }

        // When transactions are nested we only begin/commit/rollback the outermost ones
        if ($this->_trans_depth > 0)
        {
            $this->_trans_depth += 1;
            return;
        }

        $this->trans_begin($test_mode);
        $this->_trans_depth += 1;
    }

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

    /**
     * Complete Transaction
     *
     * @return  bool
     */
    public function trans_complete()
    {
        if ( ! $this->trans_enabled)
        {
            return FALSE;
        }

        // When transactions are nested we only begin/commit/rollback the outermost ones
        if ($this->_trans_depth > 1)
        {
            $this->_trans_depth -= 1;
            return TRUE;
        }
        else
        {
            $this->_trans_depth = 0;
        }

        // The query() function will set this flag to FALSE in the event that a query failed
        if ($this->_trans_status === FALSE)
        {
            $this->trans_rollback();

            // If we are NOT running in strict mode, we will reset
            // the _trans_status flag so that subsequent groups of transactions
            // will be permitted.
            if ($this->trans_strict === FALSE)
            {
                $this->_trans_status = TRUE;
            }

            log_message('debug', 'DB Transaction Failure');
            return FALSE;
        }

        $this->trans_commit();
        return TRUE;
    }

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

    /**
     * Lets you retrieve the transaction flag to determine if it has failed
     *
     * @return  bool
     */
    public function trans_status()
    {
        return $this->_trans_status;
    }

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

    /**
     * Compile Bindings
     *
     * @param   string  the sql statement
     * @param   array   an array of bind data
     * @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;
        }

        do
        {
            $c--;
            $sql = substr_replace($sql, $this->escape($binds[$c]), $matches[0][$c][1], $ml);
        }
        while ($c !== 0);

        return $sql;
    }

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

    /**
     * Determines if a query is a "write" type.
     *
     * @param   string  An SQL query string
     * @return  bool
     */
    public function is_write_type($sql)
    {
        return (bool) preg_match('/^\s*"?(SET|INSERT|UPDATE|DELETE|REPLACE|CREATE|DROP|TRUNCATE|LOAD DATA|COPY|ALTER|RENAME|GRANT|REVOKE|LOCK|UNLOCK|REINDEX)\s+/i', $sql);
    }

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

    /**
     * Calculate the aggregate query elapsed time
     *
     * @param   int The number of decimal places
     * @return  int
     */
    public function elapsed_time($decimals = 6)
    {
        return number_format($this->benchmark, $decimals);
    }

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

    /**
     * Returns the total number of queries
     *
     * @return  int
     */
    public function total_queries()
    {
        return $this->query_count;
    }

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

    /**
     * Returns the last query that was executed
     *
     * @return  string
     */
    public function last_query()
    {
        return end($this->queries);
    }

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

    /**
     * "Smart" Escape String
     *
     * Escapes data based on type
     * Sets boolean and null types
     *
     * @param   string
     * @return  mixed
     */
    public function escape($str)
    {
        if (is_string($str) OR method_exists($str, '__toString'))
        {
            return "'".$this->escape_str($str)."'";
        }
        elseif (is_bool($str))
        {
            return ($str === FALSE) ? 0 : 1;
        }
        elseif (is_null($str))
        {
            return 'NULL';
        }

        return $str;
    }

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

    /**
     * Escape LIKE String
     *
     * Calls the individual driver for platform
     * specific escaping for LIKE conditions
     *
     * @param   string
     * @return  mixed
     */
    public function escape_like_str($str)
    {
        return $this->escape_str($str, TRUE);
    }

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

    /**
     * Primary
     *
     * Retrieves the primary key. It assumes that the row in the first
     * position is the primary key
     *
     * @param   string  the table name
     * @return  string
     */
    public function primary($table = '')
    {
        $fields = $this->list_fields($table);
        return is_array($fields) ? current($fields) : FALSE;
    }

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

    /**
     * "Count All" query
     *
     * Generates a platform-specific query string that counts all records in
     * the specified database
     *
     * @param   string
     * @return  int
     */
    public function count_all($table = '')
    {
        if ($table === '')
        {
            return 0;
        }

        $query = $this->query($this->_count_string.$this->escape_identifiers('numrows').' FROM '.$this->protect_identifiers($table, TRUE, NULL, FALSE));
        if ($query->num_rows() === 0)
        {
            return 0;
        }

        $query = $query->row();
        $this->_reset_select();
        return (int) $query->numrows;
    }

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

    /**
     * Returns an array of table names
     *
     * @return  array
     */
    public function list_tables($constrain_by_prefix = FALSE)
    {
        // Is there a cached result?
        if (isset($this->data_cache['table_names']))
        {
            return $this->data_cache['table_names'];
        }

        if (FALSE === ($sql = $this->_list_tables($constrain_by_prefix)))
        {
            return ($this->db_debug) ? $this->display_error('db_unsupported_function') : FALSE;
        }

        $this->data_cache['table_names'] = array();
        $query = $this->query($sql);

        foreach ($query->result_array() as $row)
        {
            // Do we know from which column to get the table name?
            if ( ! isset($key))
            {
                if (isset($row['table_name']))
                {
                    $key = 'table_name';
                }
                elseif (isset($row['TABLE_NAME']))
                {
                    $key = 'TABLE_NAME';
                }
                else
                {
                    /* We have no other choice but to just get the first element's key.
                     * Due to array_shift() accepting it's argument by reference, if
                     * E_STRICT is on, this would trigger a warning. So we'll have to
                     * assign it first.
                     */
                    $key = array_keys($row);
                    $key = array_shift($key);
                }
            }

            $this->data_cache['table_names'][] = $row[$key];
        }

        return $this->data_cache['table_names'];
    }

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

    /**
     * Determine if a particular table exists
     *
     * @return  bool
     */
    public function table_exists($table_name)
    {
        return in_array($this->protect_identifiers($table_name, TRUE, FALSE, FALSE), $this->list_tables());
    }

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

    /**
     * Fetch Field Names
     *
     * @param   string  the table name
     * @return  array
     */
    public function list_fields($table = '')
    {
        // Is there a cached result?
        if (isset($this->data_cache['field_names'][$table]))
        {
            return $this->data_cache['field_names'][$table];
        }

        if ($table === '')
        {
            return ($this->db_debug) ? $this->display_error('db_field_param_missing') : FALSE;
        }

        if (FALSE === ($sql = $this->_list_columns($table)))
        {
            return ($this->db_debug) ? $this->display_error('db_unsupported_function') : FALSE;
        }

        $query = $this->query($sql);
        $this->data_cache['field_names'][$table] = array();

        foreach ($query->result_array() as $row)
        {
            // Do we know from where to get the column's name?
            if ( ! isset($key))
            {
                if (isset($row['column_name']))
                {
                    $key = 'column_name';
                }
                elseif (isset($row['COLUMN_NAME']))
                {
                    $key = 'COLUMN_NAME';
                }
                else
                {
                    /* We have no other choice but to just get the first element's key.
                     * Due to array_shift() accepting it's argument by reference, if
                     * E_STRICT is on, this would trigger a warning. So we'll have to
                     * assign it first.
                     */
                    $key = array_keys($row);
                    $key = array_shift($key);
                }
            }

            $this->data_cache['field_names'][$table][] = $row[$key];
        }

        return $this->data_cache['field_names'][$table];
    }

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

    /**
     * Determine if a particular field exists
     *
     * @param   string
     * @param   string
     * @return  bool
     */
    public function field_exists($field_name, $table_name)
    {
        return in_array($field_name, $this->list_fields($table_name));
    }

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

    /**
     * Returns an object with field data
     *
     * @param   string  the table name
     * @return  object
     */
    public function field_data($table = '')
    {
        if ($table === '')
        {
            return ($this->db_debug) ? $this->display_error('db_field_param_missing') : FALSE;
        }

        $query = $this->query($this->_field_data($this->protect_identifiers($table, TRUE, NULL, FALSE)));
        return $query->field_data();
    }

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

    /**
     * Escape the SQL Identifiers
     *
     * This function escapes column and table names
     *
     * @param   mixed
     * @return  mixed
     */
    public function escape_identifiers($item)
    {
        if ($this->_escape_char === '' OR empty($item))
        {
            return $item;
        }
        elseif (is_array($item))
        {
            foreach ($item as $key => $value)
            {
                $item[$key] = $this->escape_identifiers($value);
            }

            return $item;
        }
        // Avoid breaking functions and literal values inside queries
        elseif (ctype_digit($item) OR $item[0] === "'" OR ($this->_escape_char !== '"' && $item[0] === '"') OR strpos($item, '(') !== FALSE)
        {
            return $item;
        }

        static $preg_ec = array();

        if (empty($preg_ec))
        {
            if (is_array($this->_escape_char))
            {
                $preg_ec = array(
                        preg_quote($this->_escape_char[0]), preg_quote($this->_escape_char[1]),
                        $this->_escape_char[0], $this->_escape_char[1]
                        );
            }
            else
            {
                $preg_ec[0] = $preg_ec[1] = preg_quote($this->_escape_char);
                $preg_ec[2] = $preg_ec[3] = $this->_escape_char;
            }
        }

        foreach ($this->_reserved_identifiers as $id)
        {
            if (strpos($item, '.'.$id) !== FALSE)
            {
                return preg_replace('/'.$preg_ec[0].'?([^'.$preg_ec[1].'\.]+)'.$preg_ec[1].'?\./i', $preg_ec[2].'$1'.$preg_ec[3].'.', $item);
            }
        }

        return preg_replace('/'.$preg_ec[0].'?([^'.$preg_ec[1].'\.]+)'.$preg_ec[1].'?(\.)?/i', $preg_ec[2].'$1'.$preg_ec[3].'$2', $item);
    }

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

    /**
     * Generate an insert string
     *
     * @param   string  the table upon which the query will be performed
     * @param   array   an associative array data of key/values
     * @return  string
     */
    public function insert_string($table, $data)
    {
        $fields = $values = array();

        foreach ($data as $key => $val)
        {
            $fields[] = $this->escape_identifiers($key);
            $values[] = $this->escape($val);
        }

        return $this->_insert($this->protect_identifiers($table, TRUE, NULL, FALSE), $fields, $values);
    }

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

    /**
     * Insert statement
     *
     * Generates a platform-specific insert string from the supplied data
     *
     * @param   string  the table name
     * @param   array   the insert keys
     * @param   array   the insert values
     * @return  string
     */
    protected function _insert($table, $keys, $values)
    {
        return 'INSERT INTO '.$table.' ('.implode(', ', $keys).') VALUES ('.implode(', ', $values).')';
    }

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

    /**
     * Generate an update string
     *
     * @param   string  the table upon which the query will be performed
     * @param   array   an associative array data of key/values
     * @param   mixed   the "where" statement
     * @return  string
     */
    public function update_string($table, $data, $where)
    {
        if ($where === '')
        {
            return FALSE;
        }

        $fields = array();
        foreach ($data as $key => $val)
        {
            $fields[$this->protect_identifiers($key)] = $this->escape($val);
        }

        if ( ! is_array($where))
        {
            $dest = array($where);
        }
        else
        {
            $dest = array();
            foreach ($where as $key => $val)
            {
                $prefix = (count($dest) === 0) ? '' : ' AND ';
                $key = $this->protect_identifiers($key);

                if ($val !== '')
                {
                    if ( ! $this->_has_operator($key))
                    {
                        $key .= ' =';
                    }

                    $val = ' '.$this->escape($val);
                }

                $dest[] = $prefix.$key.$val;
            }
        }

        return $this->_update($this->protect_identifiers($table, TRUE, NULL, FALSE), $fields, $dest);
    }

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

    /**
     * Update statement
     *
     * Generates a platform-specific update string from the supplied data
     *
     * @param   string  the table name
     * @param   array   the update data
     * @param   array   the where clause
     * @param   array   the orderby clause
     * @param   array   the limit clause
     * @param   array   the like clause
     * @return  string
     */
    protected function _update($table, $values, $where, $orderby = array(), $limit = FALSE, $like = array())
    {
        foreach ($values as $key => $val)
        {
            $valstr[] = $key.' = '.$val;
        }

        $where = empty($where) ? '' : ' WHERE '.implode(' ', $where);

        if ( ! empty($like))
        {
            $where .= ($where === '' ? ' WHERE ' : ' AND ').implode(' ', $like);
        }

        return 'UPDATE '.$table.' SET '.implode(', ', $valstr)
            .$where
            .(count($orderby) > 0 ? ' ORDER BY '.implode(', ', $orderby) : '')
            .($limit ? ' LIMIT '.$limit : '');
    }

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

    /**
     * Tests whether the string has an SQL operator
     *
     * @param   string
     * @return  bool
     */
    protected function _has_operator($str)
    {
        return (bool) preg_match('/(\s|<|>|!|=|IS NULL|IS NOT NULL|BETWEEN)/i', trim($str));
    }

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

    /**
     * Returns the SQL string operator
     *
     * @param   string
     * @return  string
     */
    protected function _get_operator($str)
    {
        return preg_match('/(=|!|<|>| IS NULL| IS NOT NULL| BETWEEN)/i', $str, $match)
            ? $match[1] : FALSE;
    }

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

    /**
     * Enables a native PHP function to be run, using a platform agnostic wrapper.
     *
     * @param   string  the function name
     * @param   mixed   any parameters needed by the function
     * @return  mixed
     */
    public function call_function($function)
    {
        $driver = ($this->dbdriver === 'postgre') ? 'pg_' : $this->dbdriver.'_';

        if (FALSE === strpos($driver, $function))
        {
            $function = $driver.$function;
        }

        if ( ! function_exists($function))
        {
            return ($this->db_debug) ? $this->display_error('db_unsupported_function') : FALSE;
        }

        return (func_num_args() > 1)
            ? call_user_func_array($function, array_splice(func_get_args(), 1))
            : call_user_func($function);
    }

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

    /**
     * Set Cache Directory Path
     *
     * @param   string  the path to the cache directory
     * @return  void
     */
    public function cache_set_path($path = '')
    {
        $this->cachedir = $path;
    }

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

    /**
     * Enable Query Caching
     *
     * @return  bool    cache_on value
     */
    public function cache_on()
    {
        return $this->cache_on = TRUE;
    }

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

    /**
     * Disable Query Caching
     *
     * @return  bool    cache_on value
     */
    public function cache_off()
    {
        return $this->cache_on = FALSE;
    }

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

    /**
     * Delete the cache files associated with a particular URI
     *
     * @return  bool
     */
    public function cache_delete($segment_one = '', $segment_two = '')
    {
        return ($this->_cache_init())
            ? $this->CACHE->delete($segment_one, $segment_two)
            : FALSE;
    }

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

    /**
     * Delete All cache files
     *
     * @return  bool
     */
    public function cache_delete_all()
    {
        return ($this->_cache_init())
            ? $this->CACHE->delete_all()
            : FALSE;
    }

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

    /**
     * Initialize the Cache Class
     *
     * @return  bool
     */
    protected function _cache_init()
    {
        if (class_exists('CI_DB_Cache'))
        {
            if (is_object($this->CACHE))
            {
                return TRUE;
            }
        }
        elseif ( ! @include_once(BASEPATH.'database/DB_cache.php'))
        {
            return $this->cache_off();
        }

        $this->CACHE = new CI_DB_Cache($this); // pass db object to support multiple db connections and returned db objects
        return TRUE;
    }

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

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

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

    /**
     * Close DB Connection
     *
     * This method would be overriden by most of the drivers.
     *
     * @return  void
     */
    protected function _close()
    {
        $this->conn_id = FALSE;
    }

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

    /**
     * Display an error message
     *
     * @param   string  the error message
     * @param   string  any "swap" values
     * @param   bool    whether to localize the message
     * @return  string  sends the application/error_db.php template
     */
    public function display_error($error = '', $swap = '', $native = FALSE)
    {
        $LANG =& load_class('Lang', 'core');
        $LANG->load('db');

        $heading = $LANG->line('db_error_heading');

        if ($native === TRUE)
        {
            $message = (array) $error;
        }
        else
        {
            $message = ( ! is_array($error)) ? array(str_replace('%s', $swap, $LANG->line($error))) : $error;
        }

        // Find the most likely culprit of the error by going through
        // the backtrace until the source file is no longer in the
        // database folder.
        $trace = debug_backtrace();
        foreach ($trace as $call)
        {
            if (isset($call['file'], $call['class']) && strpos($call['file'], BASEPATH.'database') === FALSE && strpos($call['class'], 'Loader') !== FALSE)
            {
                // Found it - use a relative path for safety
                $message[] = 'Filename: '.str_replace(array(APPPATH, BASEPATH), '', $call['file']);
                $message[] = 'Line Number: '.$call['line'];
                break;
            }
        }

        $error =& load_class('Exceptions', 'core');
        echo $error->show_error($heading, $message, 'error_db');
        exit;
    }

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

    /**
     * Protect Identifiers
     *
     * This function is used extensively by the Query Builder class, and by
     * a couple functions in this class.
     * It takes a column or table name (optionally with an alias) and inserts
     * the table prefix onto it. Some logic is necessary in order to deal with
     * column names that include the path. Consider a query like this:
     *
     * SELECT * FROM hostname.database.table.column AS c FROM hostname.database.table
     *
     * Or a query with aliasing:
     *
     * SELECT m.member_id, m.member_name FROM members AS m
     *
     * Since the column name can include up to four segments (host, DB, table, column)
     * or also have an alias prefix, we need to do a bit of work to figure this out and
     * insert the table prefix (if it exists) in the proper position, and escape only
     * the correct identifiers.
     *
     * @param   string
     * @param   bool
     * @param   mixed
     * @param   bool
     * @return  string
     */
    public function protect_identifiers($item, $prefix_single = FALSE, $protect_identifiers = NULL, $field_exists = TRUE)
    {
        if ( ! is_bool($protect_identifiers))
        {
            $protect_identifiers = $this->_protect_identifiers;
        }

        if (is_array($item))
        {
            $escaped_array = array();
            foreach ($item as $k => $v)
            {
                $escaped_array[$this->protect_identifiers($k)] = $this->protect_identifiers($v, $prefix_single, $protect_identifiers, $field_exists);
            }

            return $escaped_array;
        }

        // This is basically a bug fix for queries that use MAX, MIN, etc.
        // If a parenthesis is found we know that we do not need to
        // escape the data or add a prefix. There's probably a more graceful
        // way to deal with this, but I'm not thinking of it -- Rick
        if (strpos($item, '(') !== FALSE)
        {
            return $item;
        }

        // Convert tabs or multiple spaces into single spaces
        $item = preg_replace('/\s+/', ' ', $item);

        // If the item has an alias declaration we remove it and set it aside.
        // Note: strripos() is used in order to support spaces in table names
        if ($offset = strripos($item, ' AS '))
        {
            $alias = ($protect_identifiers)
                    ? substr($item, $offset, 4).$this->escape_identifiers(substr($item, $offset + 4))
                    : substr($item, $offset);
            $item = substr($item, 0, $offset);
        }
        elseif ($offset = strrpos($item, ' '))
        {
            $alias = ($protect_identifiers)
                    ? ' '.$this->escape_identifiers(substr($item, $offset + 1))
                    : substr($item, $offset);
            $item = substr($item, 0, $offset);
        }
        else
        {
            $alias = '';
        }

        // Break the string apart if it contains periods, then insert the table prefix
        // in the correct location, assuming the period doesn't indicate that we're dealing
        // with an alias. While we're at it, we will escape the components
        if (strpos($item, '.') !== FALSE)
        {
            $parts  = explode('.', $item);

            // Does the first segment of the exploded item match
            // one of the aliases previously identified? If so,
            // we have nothing more to do other than escape the item
            if (in_array($parts[0], $this->qb_aliased_tables))
            {
                if ($protect_identifiers === TRUE)
                {
                    foreach ($parts as $key => $val)
                    {
                        if ( ! in_array($val, $this->_reserved_identifiers))
                        {
                            $parts[$key] = $this->escape_identifiers($val);
                        }
                    }

                    $item = implode('.', $parts);
                }

                return $item.$alias;
            }

            // Is there a table prefix defined in the config file? If not, no need to do anything
            if ($this->dbprefix !== '')
            {
                // We now add the table prefix based on some logic.
                // Do we have 4 segments (hostname.database.table.column)?
                // If so, we add the table prefix to the column name in the 3rd segment.
                if (isset($parts[3]))
                {
                    $i = 2;
                }
                // Do we have 3 segments (database.table.column)?
                // If so, we add the table prefix to the column name in 2nd position
                elseif (isset($parts[2]))
                {
                    $i = 1;
                }
                // Do we have 2 segments (table.column)?
                // If so, we add the table prefix to the column name in 1st segment
                else
                {
                    $i = 0;
                }

                // This flag is set when the supplied $item does not contain a field name.
                // This can happen when this function is being called from a JOIN.
                if ($field_exists === FALSE)
                {
                    $i++;
                }

                // Verify table prefix and replace if necessary
                if ($this->swap_pre !== '' && strpos($parts[$i], $this->swap_pre) === 0)
                {
                    $parts[$i] = preg_replace('/^'.$this->swap_pre.'(\S+?)/', $this->dbprefix.'\\1', $parts[$i]);
                }
                // We only add the table prefix if it does not already exist
                elseif (strpos($parts[$i], $this->dbprefix) !== 0)
                {
                    $parts[$i] = $this->dbprefix.$parts[$i];
                }

                // Put the parts back together
                $item = implode('.', $parts);
            }

            if ($protect_identifiers === TRUE)
            {
                $item = $this->escape_identifiers($item);
            }

            return $item.$alias;
        }

        // Is there a table prefix? If not, no need to insert it
        if ($this->dbprefix !== '')
        {
            // Verify table prefix and replace if necessary
            if ($this->swap_pre !== '' && strpos($item, $this->swap_pre) === 0)
            {
                $item = preg_replace('/^'.$this->swap_pre.'(\S+?)/', $this->dbprefix.'\\1', $item);
            }
            // Do we prefix an item with no segments?
            elseif ($prefix_single === TRUE && strpos($item, $this->dbprefix) !== 0)
            {
                $item = $this->dbprefix.$item;
            }
        }

        if ($protect_identifiers === TRUE && ! in_array($item, $this->_reserved_identifiers))
        {
            $item = $this->escape_identifiers($item);
        }

        return $item.$alias;
    }

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

    /**
     * Dummy method that allows Query Builder class to be disabled
     * and keep count_all() working.
     *
     * @return  void
     */
    protected function _reset_select()
    {
    }

}

/* End of file DB_driver.php */
/* Location: ./system/database/DB_driver.php */