<?php

/**
 * @defgroup session Session
 * Implements session concerns such as the session manager, session objects, etc.
 */

/**
 * @file classes/session/Session.inc.php
 *
 * Copyright (c) 2014-2019 Simon Fraser University
 * Copyright (c) 2000-2019 John Willinsky
 * Distributed under the GNU GPL v2. For full terms see the file docs/COPYING.
 *
 * @class Session
 * @ingroup session
 * @see SessionDAO
 *
 * @brief Maintains user state information from one request to the next.
 */

class Session extends DataObject {

	/** The User object associated with this session */
	var $user;


	/**
	 * Get a session variable's value.
	 * @param $key string
	 * @return mixed
	 */
	function getSessionVar($key) {
		return isset($_SESSION[$key]) ? $_SESSION[$key] : null;
	}

	/**
	 * Get a session variable's value.
	 * @param $key string
	 * @param $value mixed
	 * @return mixed
	 */
	function setSessionVar($key, $value) {
		$_SESSION[$key] = $value;
		return $value;
	}

	/**
	 * Unset (delete) a session variable.
	 * @param $key string
	 */
	function unsetSessionVar($key) {
		if (isset($_SESSION[$key])) {
			unset($_SESSION[$key]);
		}
	}

	//
	// Get/set methods
	//

	/**
	 * Get user ID (0 if anonymous user).
	 * @return int
	 */
	function getUserId() {
		return $this->getData('userId');
	}

	/**
	 * Set user ID.
	 * @param $userId int
	 */
	function setUserId($userId) {
		if (!isset($userId) || empty($userId)) {
			$this->user = null;
			$userId = null;

		} else if ($userId != $this->getData('userId')) {
			$userDao = DAORegistry::getDAO('UserDAO');
			$this->user = $userDao->getById($userId);
			if (!isset($this->user)) {
				$userId = null;
			}
		}
		$this->setData('userId', $userId);
	}

	/**
	 * Get IP address.
	 * @return string
	 */
	function getIpAddress() {
		return $this->getData('ipAddress');
	}

	/**
	 * Set IP address.
	 * @param $ipAddress string
	 */
	function setIpAddress($ipAddress) {
		$this->setData('ipAddress', $ipAddress);
	}

	/**
	 * Get user agent.
	 * @return string
	 */
	function getUserAgent() {
		return $this->getData('userAgent');
	}

	/**
	 * Set user agent.
	 * @param $userAgent string
	 */
	function setUserAgent($userAgent) {
		$this->setData('userAgent', $userAgent);
	}

	/**
	 * Get time (in seconds) since session was created.
	 * @return int
	 */
	function getSecondsCreated() {
		return $this->getData('created');
	}

	/**
	 * Set time (in seconds) since session was created.
	 * @param $created int
	 */
	function setSecondsCreated($created) {
		$this->setData('created', $created);
	}

	/**
	 * Get time (in seconds) since session was last used.
	 * @return int
	 */
	function getSecondsLastUsed() {
		return $this->getData('lastUsed');
	}

	/**
	 * Set time (in seconds) since session was last used.
	 * @param $lastUsed int
	 */
	function setSecondsLastUsed($lastUsed) {
		$this->setData('lastUsed', $lastUsed);
	}

	/**
	 * Check if session is to be saved across browser sessions.
	 * @return boolean
	 */
	function getRemember() {
		return $this->getData('remember');
	}

	/**
	 * Set whether session is to be saved across browser sessions.
	 * @param $remember boolean
	 */
	function setRemember($remember) {
		$this->setData('remember', $remember);
	}

	/**
	 * Get all session parameters.
	 * @return array
	 */
	function getSessionData() {
		return $this->getData('data');
	}

	/**
	 * Set session parameters.
	 * @param $data array
	 */
	function setSessionData($data) {
		$this->setData('data', $data);
	}

	/**
	 * Get the domain with which the session is registered
	 * @return array
	 */
	function getDomain() {
		return $this->getData('domain');
	}

	/**
	 * Set the domain with which the session is registered
	 * @param $data array
	 */
	function setDomain($data) {
		$this->setData('domain', $data);
	}

	/**
	 * Get user associated with this session (null if anonymous user).
	 * @return User
	 */
	function &getUser() {
		return $this->user;
	}

	/**
	 * Get a usable CSRF token (generating if necessary).
	 * @return string
	 */
	function getCSRFToken() {
		$csrf = $this->getSessionVar('csrf');
		if (!is_array($csrf) || time() > $csrf['timestamp'] + (60*60)) { // 1 hour token expiry
			// Generate random data
			if (function_exists('openssl_random_pseudo_bytes')) $data = openssl_random_pseudo_bytes(128);
			elseif (function_exists('random_bytes')) $data = random_bytes(128);
			else $data = sha1(mt_rand());

			// Hash the data
			$token = null;
			$salt = Config::getVar('security', 'salt');
			$algos = hash_algos();
			foreach (array('sha256', 'sha1', 'md5') as $algo) {
				if (in_array($algo, $algos)) {
					$token = hash_hmac($algo, $data, $salt);
				}
			}
			if (!$token) $token = md5($data . $salt);

			$csrf = $this->setSessionVar('csrf', array(
				'timestamp' => time(),
				'token' => $token,
			));
		} else {
			// Extend timeout of CSRF token
			$csrf['timestamp'] = time();
			$this->setSessionVar('csrf', $csrf);
		}
		return $csrf['token'];
	}
}


