<?php
/**
 * THttpSession class
 *
 * @author Qiang Xue <qiang.xue@gmail.com>
 * @link https://github.com/pradosoft/prado
 * @license https://github.com/pradosoft/prado/blob/master/LICENSE
 */

namespace Prado\Web;

use Prado\Exceptions\TInvalidDataValueException;
use Prado\Exceptions\TInvalidOperationException;
use Prado\TPropertyValue;
use Prado;

/**
 * THttpSession class
 *
 * THttpSession provides session-level data management and the related configurations.
 * To start the session, call {@link open}; to complete and send out session data, call {@link close};
 * to destroy the session, call {@link destroy}. If AutoStart is true, then the session
 * will be started once the session module is loaded and initialized.
 *
 * To access data stored in session, use THttpSession like an associative array. For example,
 * <code>
 *   $session=new THttpSession;
 *   $session->open();
 *   $value1=$session['name1'];  // get session variable 'name1'
 *   $value2=$session['name2'];  // get session variable 'name2'
 *   foreach($session as $name=>$value) // traverse all session variables
 *   $session['name3']=$value3;  // set session variable 'name3'
 * </code>
 *
 * The following configurations are available for session:
 * {@link setAutoStart AutoStart}, {@link setCookieMode CookieMode},
 * {@link setSavePath SavePath},
 * {@link setUseCustomStorage UseCustomStorage}, {@link setGCProbability GCProbability},
 * {@link setTimeout Timeout}.
 * See the corresponding setter and getter documentation for more information.
 * Note, these properties must be set before the session is started.
 *
 * THttpSession can be inherited with customized session storage method.
 * Override {@link _open}, {@link _close}, {@link _read}, {@link _write}, {@link _destroy} and {@link _gc}
 * and set {@link setUseCustomStorage UseCustomStorage} to true.
 * Then, the session data will be stored using the above methods.
 *
 * By default, THttpSession is registered with {@link TApplication} as the
 * request module. It can be accessed via {@link TApplication::getSession()}.
 *
 * THttpSession may be configured in application configuration file as follows,
 * <code>
 * <module id="session" class="THttpSession" SessionName="SSID" SavePath="/tmp"
 *         CookieMode="Allow" UseCustomStorage="false" AutoStart="true" GCProbability="1"
 *         UseTransparentSessionID="true" TimeOut="3600" />
 * </code>
 * where {@link getSessionName SessionName}, {@link getSavePath SavePath},
 * {@link getCookieMode CookieMode}, {@link getUseCustomStorage
 * UseCustomStorage}, {@link getAutoStart AutoStart}, {@link getGCProbability
 * GCProbability}, {@link getUseTransparentSessionID UseTransparentSessionID}
 * and {@link getTimeout TimeOut} are configurable properties of THttpSession.
 *
 * To avoid the possibility of identity theft through some variants of XSS attacks,
 * THttpSessionshould always be configured to enforce HttpOnly setting on session cookie.
 * The HttpOnly setting is disabled by default. To enable it, configure the THttpSession
 * module as follows,
 * <code>
 * <module id="session" class="THttpSession" Cookie.HttpOnly="true" >
 * </code>
 *
 * @author Qiang Xue <qiang.xue@gmail.com>
 * @since 3.0
 */
class THttpSession extends \Prado\TApplicationComponent implements \IteratorAggregate, \ArrayAccess, \Countable, \Prado\IModule
{
	/**
	 * @var bool whether this module has been initialized
	 */
	private $_initialized = false;
	/**
	 * @var bool whether the session has started
	 */
	private $_started = false;
	/**
	 * @var bool whether the session should be started when the module is initialized
	 */
	private $_autoStart = false;
	/**
	 * @var THttpCookie cookie to be used to store session ID and other data
	 */
	private $_cookie;
	/**
	 * @var string module id
	 */
	private $_id;
	/**
	 * @var bool
	 */
	private $_customStorage = false;

	/**
	 * @return string id of this module
	 */
	public function getID()
	{
		return $this->_id;
	}

	/**
	 * @param string $value id of this module
	 */
	public function setID($value)
	{
		$this->_id = $value;
	}

	/**
	 * Initializes the module.
	 * This method is required by IModule.
	 * If AutoStart is true, the session will be started.
	 * @param \Prado\Xml\TXmlElement $config module configuration
	 */
	public function init($config)
	{
		if ($this->_autoStart) {
			$this->open();
		}
		$this->_initialized = true;
		$this->getApplication()->setSession($this);
		register_shutdown_function([$this, "close"]);
	}

	/**
	 * Starts the session if it has not started yet.
	 */
	public function open()
	{
		if (!$this->_started) {
			if ($this->_customStorage) {
				session_set_save_handler([$this, '_open'], [$this, '_close'], [$this, '_read'], [$this, '_write'], [$this, '_destroy'], [$this, '_gc']);
			}
			if ($this->_cookie !== null) {
				if (PHP_VERSION_ID >= 70300) {
					session_set_cookie_params($this->_cookie->getPhpOptions('lifetime'));
				} else {
					session_set_cookie_params($this->_cookie->getExpire(), $this->_cookie->getPath(), $this->_cookie->getDomain(), $this->_cookie->getSecure(), $this->_cookie->getHttpOnly());
				}
			}
			if (ini_get('session.auto_start') !== '1') {
				session_start();
			}
			$this->_started = true;
		}
	}

	/**
	 * Ends the current session and store session data.
	 */
	public function close()
	{
		if ($this->_started) {
			session_write_close();
			$this->_started = false;
		}
	}

	/**
	 * Destroys all data registered to a session.
	 */
	public function destroy()
	{
		if ($this->_started) {
			session_destroy();
			$this->_started = false;
		}
	}

	/**
	 * Update the current session id with a newly generated one
	 *
	 * @param bool $deleteOld Whether to delete the old associated session or not.
	 * @return string old session id
	 * @link http://php.net/manual/en/function.session-regenerate-id.php
	 */
	public function regenerate($deleteOld = false)
	{
		$old = $this->getSessionID();
		session_regenerate_id($deleteOld);
		return $old;
	}

	/**
	 * @return bool whether the session has started
	 */
	public function getIsStarted()
	{
		return $this->_started;
	}

	/**
	 * @return string the current session ID
	 */
	public function getSessionID()
	{
		return session_id();
	}

	/**
	 * @param string $value the session ID for the current session
	 * @throws TInvalidOperationException if session is started already
	 */
	public function setSessionID($value)
	{
		if ($this->_started) {
			throw new TInvalidOperationException('httpsession_sessionid_unchangeable');
		} else {
			session_id($value);
		}
	}

	/**
	 * @return string the current session name
	 */
	public function getSessionName()
	{
		return session_name();
	}

	/**
	 * @param string $value the session name for the current session, must be an alphanumeric string, defaults to PHPSESSID
	 * @throws TInvalidOperationException if session is started already
	 */
	public function setSessionName($value)
	{
		if ($this->_started) {
			throw new TInvalidOperationException('httpsession_sessionname_unchangeable');
		} elseif (ctype_alnum($value)) {
			session_name($value);
		} else {
			throw new TInvalidDataValueException('httpsession_sessionname_invalid', $value);
		}
	}

	/**
	 * @return string the current session save path, defaults to '/tmp'.
	 */
	public function getSavePath()
	{
		return session_save_path();
	}

	/**
	 * @param string $value the current session save path
	 * @throws TInvalidOperationException if session is started already
	 */
	public function setSavePath($value)
	{
		if ($this->_started) {
			throw new TInvalidOperationException('httpsession_savepath_unchangeable');
		} elseif (is_dir($value)) {
			session_save_path(realpath($value));
		} elseif (null !== ($ns = Prado::getPathOfNamespace($value)) && is_dir($ns)) {
			session_save_path(realpath($ns));
		} else {
			throw new TInvalidDataValueException('httpsession_savepath_invalid', $value);
		}
	}

	/**
	 * @return bool whether to use user-specified handlers to store session data. Defaults to false.
	 */
	public function getUseCustomStorage()
	{
		return $this->_customStorage;
	}

	/**
	 * @param bool $value whether to use user-specified handlers to store session data.
	 * If true, make sure the methods {@link _open}, {@link _close}, {@link _read},
	 * {@link _write}, {@link _destroy}, and {@link _gc} are overridden in child
	 * class, because they will be used as the callback handlers.
	 */
	public function setUseCustomStorage($value)
	{
		$this->_customStorage = TPropertyValue::ensureBoolean($value);
	}

	/**
	 * @return THttpCookie cookie that will be used to store session ID
	 */
	public function getCookie()
	{
		if ($this->_cookie === null) {
			$this->_cookie = new THttpCookie($this->getSessionName(), $this->getSessionID());
		}
		return $this->_cookie;
	}

	/**
	 * @return THttpSessionCookieMode how to use cookie to store session ID. Defaults to THttpSessionCookieMode::Allow.
	 */
	public function getCookieMode()
	{
		if (ini_get('session.use_cookies') === '0') {
			return THttpSessionCookieMode::None;
		} elseif (ini_get('session.use_only_cookies') === '0') {
			return THttpSessionCookieMode::Allow;
		} else {
			return THttpSessionCookieMode::Only;
		}
	}

	/**
	 * @param THttpSessionCookieMode $value how to use cookie to store session ID
	 * @throws TInvalidOperationException if session is started already
	 */
	public function setCookieMode($value)
	{
		if ($this->_started) {
			throw new TInvalidOperationException('httpsession_cookiemode_unchangeable');
		} else {
			$value = TPropertyValue::ensureEnum($value, 'Prado\\Web\\THttpSessionCookieMode');
			if ($value === THttpSessionCookieMode::None) {
				ini_set('session.use_cookies', '0');
				ini_set('session.use_only_cookies', '0');
			} elseif ($value === THttpSessionCookieMode::Allow) {
				ini_set('session.use_cookies', '1');
				ini_set('session.use_only_cookies', '0');
			} else {
				ini_set('session.use_cookies', '1');
				ini_set('session.use_only_cookies', '1');
				ini_set('session.use_trans_sid', 0);
			}
		}
	}

	/**
	 * @return bool whether the session should be automatically started when the session module is initialized, defaults to false.
	 */
	public function getAutoStart()
	{
		return $this->_autoStart;
	}

	/**
	 * @param bool $value whether the session should be automatically started when the session module is initialized, defaults to false.
	 * @throws TInvalidOperationException if session is started already
	 */
	public function setAutoStart($value)
	{
		if ($this->_initialized) {
			throw new TInvalidOperationException('httpsession_autostart_unchangeable');
		} else {
			$this->_autoStart = TPropertyValue::ensureBoolean($value);
		}
	}

	/**
	 * @return int the probability (percentage) that the gc (garbage collection) process is started on every session initialization, defaults to 1 meaning 1% chance.
	 */
	public function getGCProbability()
	{
		return TPropertyValue::ensureInteger(ini_get('session.gc_probability'));
	}

	/**
	 * @param int $value the probability (percentage) that the gc (garbage collection) process is started on every session initialization.
	 * @throws TInvalidOperationException if session is started already
	 * @throws TInvalidDataValueException if the value is beyond [0,100].
	 */
	public function setGCProbability($value)
	{
		if ($this->_started) {
			throw new TInvalidOperationException('httpsession_gcprobability_unchangeable');
		} else {
			$value = TPropertyValue::ensureInteger($value);
			if ($value >= 0 && $value <= 100) {
				ini_set('session.gc_probability', $value);
				ini_set('session.gc_divisor', '100');
			} else {
				throw new TInvalidDataValueException('httpsession_gcprobability_invalid', $value);
			}
		}
	}

	/**
	 * @return bool whether transparent sid support is enabled or not, defaults to false.
	 */
	public function getUseTransparentSessionID()
	{
		return ini_get('session.use_trans_sid') === '1';
	}

	/**
	 * Ensure that {@link setCookieMode CookieMode} is not set to "None" before enabling
	 * the use of transparent session ids. Refer to the main documentation of the class
	 * THttpSession class for a configuration example.
	 *
	 * @param bool $value whether transparent sid support is enabled or not.
	 */
	public function setUseTransparentSessionID($value)
	{
		if ($this->_started) {
			throw new TInvalidOperationException('httpsession_transid_unchangeable');
		} else {
			$value = TPropertyValue::ensureBoolean($value);
			if ($value && $this->getCookieMode() == THttpSessionCookieMode::Only) {
				throw new TInvalidOperationException('httpsession_transid_cookieonly');
			}
			ini_set('session.use_trans_sid', $value ? '1' : '0');
		}
	}

	/**
	 * @return int the number of seconds after which data will be seen as 'garbage' and cleaned up, defaults to 1440 seconds.
	 */
	public function getTimeout()
	{
		return TPropertyValue::ensureInteger(ini_get('session.gc_maxlifetime'));
	}

	/**
	 * @param int $value the number of seconds after which data will be seen as 'garbage' and cleaned up
	 * @throws TInvalidOperationException if session is started already
	 */
	public function setTimeout($value)
	{
		if ($this->_started) {
			throw new TInvalidOperationException('httpsession_maxlifetime_unchangeable');
		} else {
			ini_set('session.gc_maxlifetime', $value);
		}
	}

	/**
	 * Session open handler.
	 * This method should be overridden if {@link setUseCustomStorage UseCustomStorage} is set true.
	 * @param string $savePath session save path
	 * @param string $sessionName session name
	 * @return bool whether session is opened successfully
	 */
	public function _open($savePath, $sessionName)
	{
		return true;
	}

	/**
	 * Session close handler.
	 * This method should be overridden if {@link setUseCustomStorage UseCustomStorage} is set true.
	 * @return bool whether session is closed successfully
	 */
	public function _close()
	{
		return true;
	}

	/**
	 * Session read handler.
	 * This method should be overridden if {@link setUseCustomStorage UseCustomStorage} is set true.
	 * @param string $id session ID
	 * @return string the session data
	 */
	public function _read($id)
	{
		return '';
	}

	/**
	 * Session write handler.
	 * This method should be overridden if {@link setUseCustomStorage UseCustomStorage} is set true.
	 * @param string $id session ID
	 * @param string $data session data
	 * @return bool whether session write is successful
	 */
	public function _write($id, $data)
	{
		return true;
	}

	/**
	 * Session destroy handler.
	 * This method should be overridden if {@link setUseCustomStorage UseCustomStorage} is set true.
	 * @param string $id session ID
	 * @return bool whether session is destroyed successfully
	 */
	public function _destroy($id)
	{
		return true;
	}

	/**
	 * Session GC (garbage collection) handler.
	 * This method should be overridden if {@link setUseCustomStorage UseCustomStorage} is set true.
	 * @param int $maxLifetime the number of seconds after which data will be seen as 'garbage' and cleaned up.
	 * @return bool whether session is GCed successfully
	 */
	public function _gc($maxLifetime)
	{
		return true;
	}

	//------ The following methods enable THttpSession to be TMap-like -----

	/**
	 * Returns an iterator for traversing the session variables.
	 * This method is required by the interface \IteratorAggregate.
	 * @return TSessionIterator an iterator for traversing the session variables.
	 */
	#[\ReturnTypeWillChange]
	public function getIterator()
	{
		return new TSessionIterator();
	}

	/**
	 * @return int the number of session variables
	 */
	public function getCount()
	{
		return count($_SESSION);
	}

	/**
	 * Returns the number of items in the session.
	 * This method is required by \Countable interface.
	 * @return int number of items in the session.
	 */
	public function count(): int
	{
		return $this->getCount();
	}

	/**
	 * @return array the list of session variable names
	 */
	public function getKeys()
	{
		return array_keys($_SESSION);
	}

	/**
	 * Returns the session variable value with the session variable name.
	 * This method is exactly the same as {@link offsetGet}.
	 * @param mixed $key the session variable name
	 * @return mixed the session variable value, null if no such variable exists
	 */
	public function itemAt($key)
	{
		return $_SESSION[$key] ?? null;
	}

	/**
	 * Adds a session variable.
	 * Note, if the specified name already exists, the old value will be removed first.
	 * @param mixed $key session variable name
	 * @param mixed $value session variable value
	 */
	public function add($key, $value)
	{
		$_SESSION[$key] = $value;
	}

	/**
	 * Removes a session variable.
	 * @param mixed $key the name of the session variable to be removed
	 * @return mixed the removed value, null if no such session variable.
	 */
	public function remove($key)
	{
		if (isset($_SESSION[$key])) {
			$value = $_SESSION[$key];
			unset($_SESSION[$key]);
			return $value;
		} else {
			return null;
		}
	}

	/**
	 * Removes all session variables
	 */
	public function clear()
	{
		foreach (array_keys($_SESSION) as $key) {
			unset($_SESSION[$key]);
		}
	}

	/**
	 * @param mixed $key session variable name
	 * @return bool whether there is the named session variable
	 */
	public function contains($key)
	{
		return isset($_SESSION[$key]);
	}

	/**
	 * @return array the list of all session variables in array
	 */
	public function toArray()
	{
		return $_SESSION;
	}

	/**
	 * This method is required by the interface \ArrayAccess.
	 * @param mixed $offset the offset to check on
	 * @return bool
	 */
	public function offsetExists($offset): bool
	{
		return isset($_SESSION[$offset]);
	}

	/**
	 * This method is required by the interface \ArrayAccess.
	 * @param int $offset the offset to retrieve element.
	 * @return mixed the element at the offset, null if no element is found at the offset
	 */
	#[\ReturnTypeWillChange]
	public function offsetGet($offset)
	{
		return $_SESSION[$offset] ?? null;
	}

	/**
	 * This method is required by the interface \ArrayAccess.
	 * @param int $offset the offset to set element
	 * @param mixed $item the element value
	 */
	public function offsetSet($offset, $item): void
	{
		$_SESSION[$offset] = $item;
	}

	/**
	 * This method is required by the interface \ArrayAccess.
	 * @param mixed $offset the offset to unset element
	 */
	public function offsetUnset($offset): void
	{
		unset($_SESSION[$offset]);
	}
}