<?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 3.0.0
 * @filesource
 */
defined('BASEPATH') OR exit('No direct script access allowed');

/**
 * PDO Oracle 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_pdo_oci_driver extends CI_DB_pdo_driver {

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

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

    /**
     * List of reserved identifiers
     *
     * Identifiers that must NOT be escaped.
     *
     * @var	string[]
     */
    protected $_reserved_identifiers = array('*', 'rownum');

    /**
     * ORDER BY random keyword
     *
     * @var	array
     */
    protected $_random_keyword = array('ASC', 'ASC'); // Currently not supported

    /**
     * COUNT string
     *
     * @used-by	CI_DB_driver::count_all()
     * @used-by	CI_DB_query_builder::count_all_results()
     *
     * @var	string
     */
    protected $_count_string = 'SELECT COUNT(1) AS ';

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

    /**
     * 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 = 'oci:dbname=';

            // Oracle has a slightly different PDO DSN format (Easy Connect),
            // which also supports pre-defined DSNs.
            if (empty($this->hostname) && empty($this->port)) {
                $this->dsn .= $this->database;
            } else {
                $this->dsn .= '//' . (empty($this->hostname) ? '127.0.0.1' : $this->hostname)
                        . (empty($this->port) ? '' : ':' . $this->port) . '/';

                empty($this->database) OR $this->dsn .= $this->database;
            }

            empty($this->char_set) OR $this->dsn .= ';charset=' . $this->char_set;
        } elseif (!empty($this->char_set) && strpos($this->dsn, 'charset=', 4) === FALSE) {
            $this->dsn .= ';charset=' . $this->char_set;
        }
    }

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

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

        $version_string = parent::version();
        if (preg_match('#Release\s(?<version>\d+(?:\.\d+)+)#', $version_string, $match)) {
            return $this->data_cache['version'] = $match[1];
        }

        return 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 "ALL_TABLES"';

        if ($prefix_limit === TRUE && $this->dbprefix !== '') {
            return $sql . ' WHERE "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 = '') {
        if (strpos($table, '.') !== FALSE) {
            sscanf($table, '%[^.].%s', $owner, $table);
        } else {
            $owner = $this->username;
        }

        return 'SELECT COLUMN_NAME FROM ALL_TAB_COLUMNS
			WHERE UPPER(OWNER) = ' . $this->escape(strtoupper($owner)) . '
				AND UPPER(TABLE_NAME) = ' . $this->escape(strtoupper($table));
    }

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

    /**
     * Returns an object with field data
     *
     * @param	string	$table
     * @return	array
     */
    public function field_data($table) {
        if (strpos($table, '.') !== FALSE) {
            sscanf($table, '%[^.].%s', $owner, $table);
        } else {
            $owner = $this->username;
        }

        $sql = 'SELECT COLUMN_NAME, DATA_TYPE, CHAR_LENGTH, DATA_PRECISION, DATA_LENGTH, DATA_DEFAULT, NULLABLE
			FROM ALL_TAB_COLUMNS
			WHERE UPPER(OWNER) = ' . $this->escape(strtoupper($owner)) . '
				AND 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;

            $length = ($query[$i]->CHAR_LENGTH > 0) ? $query[$i]->CHAR_LENGTH : $query[$i]->DATA_PRECISION;
            if ($length === NULL) {
                $length = $query[$i]->DATA_LENGTH;
            }
            $retval[$i]->max_length = $length;

            $default = $query[$i]->DATA_DEFAULT;
            if ($default === NULL && $query[$i]->NULLABLE === 'N') {
                $default = '';
            }
            $retval[$i]->default = $query[$i]->COLUMN_DEFAULT;
        }

        return $retval;
    }

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

    /**
     * Insert batch statement
     *
     * @param	string	$table	Table name
     * @param	array	$keys	INSERT keys
     * @param	array	$values	INSERT values
     * @return 	string
     */
    protected function _insert_batch($table, $keys, $values) {
        $keys = implode(', ', $keys);
        $sql = "INSERT ALL\n";

        for ($i = 0, $c = count($values); $i < $c; $i++) {
            $sql .= '	INTO ' . $table . ' (' . $keys . ') VALUES ' . $values[$i] . "\n";
        }

        return $sql . 'SELECT * FROM dual';
    }

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

    /**
     * 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) {
            $this->where('rownum <= ', $this->qb_limit, FALSE);
            $this->qb_limit = FALSE;
        }

        return parent::_delete($table);
    }

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

    /**
     * LIMIT
     *
     * Generates a platform-specific LIMIT clause
     *
     * @param	string	$sql	SQL Query
     * @return	string
     */
    protected function _limit($sql) {
        if (version_compare($this->version(), '12.1', '>=')) {
            // OFFSET-FETCH can be used only with the ORDER BY clause
            empty($this->qb_orderby) && $sql .= ' ORDER BY 1';

            return $sql . ' OFFSET ' . (int) $this->qb_offset . ' ROWS FETCH NEXT ' . $this->qb_limit . ' ROWS ONLY';
        }

        return 'SELECT * FROM (SELECT inner_query.*, rownum rnum FROM (' . $sql . ') inner_query WHERE rownum < ' . ($this->qb_offset + $this->qb_limit + 1) . ')'
                . ($this->qb_offset ? ' WHERE rnum >= ' . ($this->qb_offset + 1) : '');
    }

}
