<?php
/**
 * CodeIgniter
 *
 * An open source application development framework for PHP
 *
 * This content is released under the MIT License (MIT)
 *
 * Copyright (c) 2014 - 2018, 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 - 2018, 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): '');
	}

}