<?php
/**
 * Handles all manipulation of the session.
 * 
 * The static methods are used to manipulate the currently active controller's session.
 * The instance methods are used to manipulate a particular session.  There can be more than one of these created.
 * 
 * In order to support things like testing, the session is associated with a particular Controller.  In normal usage, this is loaded from
 * and saved to the regular PHP session, but for things like static-page-generation and unit-testing, you can create multiple Controllers,
 * each with their own session.
 * 
 * The instance object is basically just a way of manipulating a set of nested maps, and isn't specific to session data.
 * 
 * <b>Saving Data</b>
 * 
 * You can write a value to a users session from your PHP code using the static function {@link Session::set()}. You can add this line in any function or file you wish to save the value.
 * 
 * <code>
 * 	Session::set('MyValue', 6);
 * </code>
 * 
 * Saves the value of "6" to the MyValue session data. You can also save arrays or serialized objects in session (but note there may be size restrictions as to how much you can save)
 * 
 * <code>
 * 	// save a variable
 * 	$var = 1;
 * 	Session::set('MyVar', $var);
 * 
 * 	// saves an array
 * 	Session::set('MyArrayOfValues', array('1','2','3'));
 * 
 * 	// saves an object (you'll have to unserialize it back)
 * 	$object = new Object();
 * 
 * 	Session::set('MyObject', serialize($object));
 * </code>
 * 
 * <b>Accessing Data</b>
 * 
 * Once you have saved a value to the Session you can access it by using the {@link Session::get()} function. 
 * Like the {@link Session::set()} function you can use this anywhere in your PHP files.
 * 
 * The values in the comments are the values stored from the previous example.
 * 
 * <code>
 * public function bar() {
 * 	$value = Session::get('MyValue'); // $value = 6
 * 	$var   = Session::get('MyVar'); // $var = 1 
 * 	$array = Session::get('MyArrayOfValues'); // $array = array(1,2,3)
 * 	$object = Session::get('MyObject', unserialize($object)); // $object = Object()
 * }
 * </code>
 * 
 * You can also get all the values in the session at once. This is useful for debugging.
 * 
 * <code>
 * Session::get_all(); // returns an array of all the session values.
 * </code>
 * 
 * <b>Clearing Data</b>
 * 
 * Once you have accessed a value from the Session it doesn't automatically wipe the value from the Session, you have to specifically remove it. To clear a value you can either delete 1 session value by the name that you saved it
 * 
 * <code>
 * Session::clear('MyValue'); // myvalue is no longer 6.
 * </code>
 * 
 * Or you can clear every single value in the session at once. Note SilverStripe stores some of its own session data including form and page comment information. None of this is vital but clear_all will clear everything.
 * 
 * <code>
 * 	Session::clear_all();
 * </code>
 * 
 * @see Cookie
 * @todo This class is currently really basic and could do with a more well-thought-out implementation.
 *
 * @package framework
 * @subpackage control
 */

class Session {

	/**
	 * @var $timeout Set session timeout
	 */
	protected static $timeout = 0;
	
	protected static $session_ips = array();

	protected static $cookie_domain;

	protected static $cookie_path;
	
	protected static $session_store_path;

	protected static $cookie_secure = false;

	/**
	 * Session data
	 */
	protected $data = array();
	
	protected $changedData = array();

	/**
	 * Start PHP session, then create a new Session object with the given start data.
	 *
	 * @param $data Can be an array of data (such as $_SESSION) or another Session object to clone.
	 */
	public function __construct($data) {
		if($data instanceof Session) $data = $data->inst_getAll();

		$this->data = $data;
	}

	/**
	 * Cookie domain, for example 'www.php.net'.
	 * 
	 * To make cookies visible on all subdomains then the domain
	 * must be prefixed with a dot like '.php.net'.
	 * 
	 * @param string $domain The domain to set
	 */
	public static function set_cookie_domain($domain) {
		self::$cookie_domain = $domain;
	}

	/**
	 * Get the cookie domain.
	 * @return string
	 */
	public static function get_cookie_domain() {
		return self::$cookie_domain;
	}

	/**
	 * Path to set on the domain where the session cookie will work.
	 * Use a single slash ('/') for all paths on the domain.
	 *
	 * @param string $path The path to set
	 */
	public static function set_cookie_path($path) {
		self::$cookie_path = $path;
	}

	/**
	 * Get the path on the domain where the session cookie will work.
	 * @return string
	 */
	public static function get_cookie_path() {
		if(self::$cookie_path) {
			return self::$cookie_path;
		} else {
			return Director::baseURL();
		}
	}

	/**
	 * Secure cookie, tells the browser to only send it over SSL.
	 * @param boolean $secure
	 */
	public static function set_cookie_secure($secure) {
		self::$cookie_secure = (bool) $secure;
	}

	/**
	 * Get if the cookie is secure
	 * @return boolean
	 */
	public static function get_cookie_secure() {
		return (bool) self::$cookie_secure;
	}

	/**
	 * Set the session store path
	 * @param string $path Filesystem path to the session store
	 */ 
	public static function set_session_store_path($path) {
		self::$session_store_path = $path;
	}
	
	/**
	 * Get the session store path
	 * @return string
	 */
	public static function get_session_store_path() {
		return self::$session_store_path;
	}

	/**
	 * Provide an <code>array</code> of rules specifing timeouts for IPv4 address ranges or
	 * individual IPv4 addresses. The key is an IP address or range and the value is the time
	 * until the session expires in seconds. For example:
	 * 
	 * Session::set_timeout_ips(array(
	 * 		'127.0.0.1' => 36000	
	 * ));
	 * 
	 * Any user connecting from 127.0.0.1 (localhost) will have their session expired after 10 hours.
	 *
	 * Session::set_timeout is used to set the timeout value for any users whose address is not in the given IP range.
	 * 
	 * @param array $session_ips Array of IPv4 rules.
	 */
	public static function set_timeout_ips($session_ips) {
		if(!is_array($session_ips)) {
			user_error("Session::set_timeout_ips expects an array as its argument", E_USER_NOTICE);
			self::$session_ips = array();
		} else {
			self::$session_ips = $session_ips;
		}
	}
	
	/**
	 * Add a value to a specific key in the session array
	 */
	public static function add_to_array($name, $val) {
		return self::current_session()->inst_addToArray($name, $val);
	}
	
	/**
	 * Set a key/value pair in the session
	 *
	 * @param string $name Key
	 * @param string $val Value
	 */
	public static function set($name, $val) {
		return self::current_session()->inst_set($name, $val);
	}
	
	/**
	 * Return a specific value by session key
	 *
	 * @param string $name Key to lookup
	 */
	public static function get($name) {
		return self::current_session()->inst_get($name);
	}
	
	/**
	 * Return all the values in session
	 *
	 * @return Array
	 */
	public static function get_all() {
		return self::current_session()->inst_getAll();
	}
		
	/**
	 * Clear a given session key, value pair.
	 *
	 * @param string $name Key to lookup
	 */
	public static function clear($name) {
		return self::current_session()->inst_clear($name);
	}
	
	/**
	 * Clear all the values
	 *
	 * @return void
	 */
	public static function clear_all() {
		self::current_session()->inst_clearAll();
		self::$default_session = null;			
	}
		
	/**
	 * Save all the values in our session to $_SESSION
	 */
	public static function save() {
		return self::current_session()->inst_save();
	}
	
	protected static $default_session = null;
	
	protected static function current_session() {
		if(Controller::has_curr()) {
			return Controller::curr()->getSession();
		} else {
			if(!self::$default_session) self::$default_session = new Session(isset($_SESSION) ? $_SESSION : array());
			return self::$default_session;
		}
	}

	public function inst_set($name, $val) {
		// Quicker execution path for "."-free names
		if(strpos($name,'.') === false) {
			$this->data[$name] = $val;
			$this->changedData[$name] = $val;

		} else {
			$names = explode('.', $name);
		
			// We still want to do this even if we have strict path checking for legacy code
			$var = &$this->data;
			$diffVar = &$this->changedData;

			// Iterate twice over the names - once to see if the value needs to be changed,
			// and secondly to get the changed data value. This is done to solve a problem
			// where iterating over the diff var would create empty arrays, and the value
			// would then not be set, inadvertently clearing session values.
			foreach($names as $n) {
				$var = &$var[$n];
			}

			if($var !== $val) {
				foreach($names as $n) {
					$diffVar = &$diffVar[$n];
				}

				$var = $val;
				$diffVar = $val;
			}
		}
	}

	public function inst_addToArray($name, $val) {
		$names = explode('.', $name);
		
		// We still want to do this even if we have strict path checking for legacy code
		$var = &$this->data;
		$diffVar = &$this->changedData;
			
		foreach($names as $n) {
			$var = &$var[$n];
			$diffVar = &$diffVar[$n];
		}
			
		$var[] = $val;
		$diffVar[sizeof($var)-1] = $val;
	}
	
	public function inst_get($name) {
		// Quicker execution path for "."-free names
		if(strpos($name,'.') === false) {
			if(isset($this->data[$name])) return $this->data[$name];
			
		} else {
			$names = explode('.', $name);
		
			if(!isset($this->data)) {
				return null;
			}
		
			$var = $this->data;

			foreach($names as $n) {
				if(!isset($var[$n])) {
					return null;
				}
				$var = $var[$n];
			}

			return $var;
		}
	}

	public function inst_clear($name) {
		$names = explode('.', $name);

		// We still want to do this even if we have strict path checking for legacy code
		$var = &$this->data;
		$diffVar = &$this->changedData;
			
		foreach($names as $n) {
			// don't clear a record that doesn't exist
			if(!isset($var[$n])) return;
			$var = &$var[$n];
		}

		// only loop to find data within diffVar if var is proven to exist in the above loop
		foreach($names as $n) {
			$diffVar = &$diffVar[$n];
		}

		if($var !== null) {
			$var = null;
			$diffVar = null;
		}
	}

	public function inst_clearAll() {
		if($this->data && is_array($this->data)) {
			foreach(array_keys($this->data) as $key) {
				$this->inst_clear($key);
			}
		}
	}

	public function inst_getAll() {
		return $this->data;
	}
	
	/**
	 * Save data to session
	 * Only save the changes, so that anyone manipulating $_SESSION directly doesn't get burned.
	 */ 
	public function inst_save() {
		if($this->changedData) {
			if(!isset($_SESSION)) Session::start();
			$this->recursivelyApply($this->changedData, $_SESSION);
		}
	}
	
	/**
	 * Recursively apply the changes represented in $data to $dest.
	 * Used to update $_SESSION
	 */	
	protected function recursivelyApply($data, &$dest) {
		foreach($data as $k => $v) {
			if(is_array($v)) {
				if(!isset($dest[$k])) $dest[$k] = array();
				$this->recursivelyApply($v, $dest[$k]);
			} else {
				$dest[$k] = $v;
			}
		}
	}

	/**
	 * Return the changed data, for debugging purposes.
	 * @return array
	 */
	public function inst_changedData() {
		return $this->changedData;
	}

	/**
	* Sets the appropriate form message in session, with type. This will be shown once,
	* for the form specified.
	*
	* @param formname the form name you wish to use ( usually $form->FormName() )
	* @param messsage the message you wish to add to it
	* @param type the type of message
	*/
	public static function setFormMessage($formname,$message,$type){
		Session::set("FormInfo.$formname.message", $message);
		Session::set("FormInfo.$formname.type", $type);
	}

	/**
	 * Initialize session.
	 *
	 * @param string $sid Start the session with a specific ID
	 */
	public static function start($sid = null) {
		$path = self::get_cookie_path();
		$domain = self::get_cookie_domain();
		$secure = self::get_cookie_secure();
		$session_path = self::get_session_store_path();

		if(!session_id() && !headers_sent()) {
			if($domain) {
				session_set_cookie_params(self::$timeout, $path, $domain, $secure /* secure */, true /* httponly */);
			} else {
				session_set_cookie_params(self::$timeout, $path, null, $secure /* secure */, true /* httponly */);
			}

			// Allow storing the session in a non standard location
			if($session_path) session_save_path($session_path);

			// @ is to supress win32 warnings/notices when session wasn't cleaned up properly
			// There's nothing we can do about this, because it's an operating system function!
			if($sid) session_id($sid);
			@session_start();
		}
	}

	/**
	 * Destroy the active session.
	 *
	 * @param bool $removeCookie If set to TRUE, removes the user's cookie, FALSE does not remove
	 */
	public static function destroy($removeCookie = true) {
		if(session_id()) {
			if($removeCookie) {
				$path = self::get_cookie_path();
				$domain = self::get_cookie_domain();
				$secure = self::get_cookie_secure(); 
				
				if($domain) {
					setcookie(session_name(), '', null, $path, $domain, $secure, true); 
				}
				else { 
					setcookie(session_name(), '', null, $path, null, $secure, true); 
				}
				
				unset($_COOKIE[session_name()]);
			}
			session_destroy();
		}
	}
	
	/**
	 * Set the timeout of a Session value
	 *
	 * @param int $timeout Time until a session expires in seconds. Defaults to expire when browser is closed.
	 */
	public static function set_timeout($timeout) {
		self::$timeout = intval($timeout);
	}
	
	public static function get_timeout() {
		return self::$timeout;
	}
}