#!/usr/bin/env python

"""The Application singleton.

`Application` and `AppServer` work together to setup up and dispatch requests.
The distinction between the two is largely historical, but AppServer
communicates directly with Adapters (or speaks protocols like HTTP), and
Application receives the (slightly) processed input from AppServer and turns
it into `Transaction`, `HTTPRequest`, `HTTPResponse`, and `Session`.

Application is a singleton, which belongs to the AppServer. You can get access
through the Transaction object (`transaction.application()`), or you can do::

	from AppServer import globalAppServer
	application = globalAppServer.application()

Settings for Application are taken from ``Configs/Application.config``,
which is used for many global settings, even if they aren't closely tied
to the Application object itself.

"""

from types import FloatType, ClassType
from UserDict import UserDict

from Common import *
from Object import Object
from ConfigurableForServerSidePath import ConfigurableForServerSidePath
from ExceptionHandler import ExceptionHandler
from HTTPRequest import HTTPRequest
from HTTPExceptions import HTTPException, HTTPSessionExpired
from Transaction import Transaction
from ASStreamOut import ConnectionAbortedError
import URLParser

debug = False

defaultConfig = {
	'PrintConfigAtStartUp': True,
	'LogActivity': True,
	'ActivityLogFilename': 'Logs/Activity.csv',
	'ActivityLogColumns': [
		'request.remoteAddress', 'request.method',
		'request.uri', 'response.size',
		'servlet.name', 'request.timeStamp',
		'transaction.duration',
		'transaction.errorOccurred'
		],
	'SessionModule': 'Session',
	'SessionStore': 'Dynamic',
	'SessionStoreDir': 'Sessions',
	'SessionTimeout': 60,
	'SessionPrefix': '',
	'SessionName': '_SID_',
	'IgnoreInvalidSession': True,
	'UseAutomaticPathSessions': False,
	'UseCookieSessions': True,
	'SessionCookiePath': None,
	'SecureSessionCookie': True,
	'ShowDebugInfoOnErrors': True,
	'EnterDebuggerOnException': False,
	'IncludeEditLink': True,
	'IncludeFancyTraceback': False,
	'FancyTracebackContext': 5,
	'UserErrorMessage': 'The site is having technical difficulties'
		' with this page. An error has been logged, and the problem'
		' will be fixed as soon as possible. Sorry!',
	'LogErrors': True,
	'ErrorLogFilename': 'Logs/Errors.csv',
	'SaveErrorMessages': True,
	'ErrorMessagesDir': 'ErrorMsgs',
	'EmailErrors': False,
	'EmailErrorReportAsAttachment': False,
	'ErrorEmailServer': 'localhost',
	'ErrorEmailHeaders': {
		'From': 'webware@mydomain',
		'To': ['webware@mydomain'],
		'Reply-to': 'webware@mydomain',
		'content-type': 'text/html',
		'Subject': 'Error'
		},
	'ErrorPage': None,
	'MaxValueLengthInExceptionReport': 500,
	'RPCExceptionReturn': 'traceback',
	'ReportRPCExceptionsInWebKit': True,
	'CacheDir': 'Cache',
	'Contexts': {
		'default': 'Examples',
		'Admin': 'Admin',
		'Examples': 'Examples',
		'Testing': 'Testing',
		'Docs': 'Docs',
		},
	'Debug': {
		'Sessions': False,
		},
	'DirectoryFile': ['index', 'Index', 'main', 'Main'],
	'UseCascadingExtensions': True,
	'ExtensionCascadeOrder': ['.py', '.psp', '.kid', '.html'],
	'ExtraPathInfo': True,
	'ExtensionsToIgnore': [
		'.pyc', '.pyo', '.tmpl', '.bak', '.py_bak',
		'.py~', '.psp~', '.kid~', '.html~', '.tmpl~'
		],
	'ExtensionsToServe': [],
	'FilesToHide': [
		'.*', '*~', '*.bak', '*.py_bak', '*.tmpl',
		'*.pyc', '*.pyo', '__init__.*', '*.config'
		],
	'FilesToServe': [],
	'UnknownFileTypes': {
		'ReuseServlets': True,
		'Technique': 'serveContent', # or redirectSansAdapter
		'CacheContent': False,
		'MaxCacheContentSize': 128*1024,
		'ReadBufferSize': 32*1024
		},
}


class EndResponse(Exception):
	"""End response exception.

	Used to prematurely break out of the awake()/respond()/sleep()
	cycle without reporting a traceback. During servlet processing,
	if this exception is caught during awake() or respond() then sleep()
	is called and the response is sent. If caught during sleep(),
	processing ends and the response is sent.

	"""
	pass


class Application(ConfigurableForServerSidePath, Object):
	"""The Application singleton.

	Purpose and usage are explained in the module docstring.

	"""


	## Init ##

	def __init__(self, server, useSessionSweeper=1):
		"""Called only by `AppServer`, sets up the Application."""

		self._server = server
		self._serverSidePath = server.serverSidePath()

		self._imp = server._imp # the import manager

		ConfigurableForServerSidePath.__init__(self)
		Object.__init__(self)

		print 'Initializing Application...'
		print 'Current directory:', os.getcwd()

		if self.setting('PrintConfigAtStartUp'):
			self.printConfig()

		self.initVersions()
		self.initErrorPage()

		self._shutDownHandlers = []

		# Initialize TaskManager:
		if self._server.isPersistent():
			from TaskKit.Scheduler import Scheduler
			self._taskManager = Scheduler(1, exceptionHandler=self.handleException)
			self._taskManager.start()
		else:
			self._taskManager = None

		# Define this before initializing URLParser, so that contexts have a
		# chance to override this. Also be sure to define it before loading the
		# sessions, in case the loading of the sessions causes an exception.
		self._exceptionHandlerClass = ExceptionHandler

		self.initSessions()
		self.makeDirs()

		URLParser.initApp(self)
		self._rootURLParser = URLParser.ContextParser(self)

		self._running = 1

		if useSessionSweeper:
			self.startSessionSweeper()

	def initErrorPage(self):
		"""Initialize the error page related attributes."""
		dirs = (self._serverSidePath,
			os.path.dirname(os.path.abspath(__file__)))
		pages = ('error404.html', '404Text.txt')
		for dir in dirs:
			for page in pages:
				try:
					self._error404 = open(os.path.join(dir, page)).read()
					if page != pages[0]:
						print 'Deprecation warning: ' \
							'Please use %s instead of %s' % pages
				except Exception:
					continue
				else:
					break
			else:
				continue
			break
		else:
			self._error404 = None
		urls = self.setting('ErrorPage') or None
		if urls:
			try:
				errors = urls.keys()
			except AttributeError:
				errors = ['Exception']
				urls = {errors[0]: urls}
			for err in errors:
				if urls[err] and not urls[err].startswith('/'):
					urls[err] = '/' + urls[err]
		self._errorPage = urls

	def initSessions(self):
		"""Initialize all session related attributes."""
		self._sessionPrefix = self.setting('SessionPrefix') or ''
		if self._sessionPrefix:
			if self._sessionPrefix == 'hostname':
				from MiscUtils.Funcs import hostName
				self._sessionPrefix = hostName()
			self._sessionPrefix += '-'
		self._sessionTimeout = self.setting('SessionTimeout')*60
		self._sessionName = self.setting('SessionName') \
			or self.defaultConfig()['SessionName']
		self._autoPathSessions = self.setting('UseAutomaticPathSessions')
		moduleName = self.setting('SessionModule')
		className = moduleName.split('.')[-1]
		try:
			exec 'from %s import %s' % (moduleName, className)
			klass = locals()[className]
			if not isinstance(klass, ClassType) \
					and not issubclass(klass, Object):
				raise ImportError
			self._sessionClass = klass
		except ImportError:
			print "ERROR: Could not import Session class '%s'" \
				" from module '%s'" % (className, moduleName)
			self._sessionClass = None
		moduleName = self.setting('SessionStore')
		if moduleName in ('Dynamic', 'File', 'Memory'):
			moduleName = 'Session%sStore' % moduleName
		self._sessionDir = self.serverSidePath(
				self.setting('SessionStoreDir') or 'Sessions')
		className = moduleName.split('.')[-1]
		try:
			exec 'from %s import %s' % (moduleName, className)
			klass = locals()[className]
			if not isinstance(klass, ClassType) \
					and not issubclass(klass, Object):
				raise ImportError
			self._sessions = klass(self)
		except ImportError:
			print "ERROR: Could not import SessionStore class '%s'" \
				" from module '%s'" % (className, moduleName)
			self._sessions = None

	def makeDirs(self):
		"""Make sure some standard directories are always available."""
		self._cacheDir = self.serverSidePath(
			self.setting('CacheDir') or 'Cache')
		self._errorMessagesDir = self.serverSidePath(
			self.setting('ErrorMessagesDir') or 'ErrorMsgs')
		for dir in (self.serverSidePath('Logs'),
				self._cacheDir, self._errorMessagesDir, self._sessionDir):
			if dir and not os.path.exists(dir):
				os.makedirs(dir)

	def initVersions(self):
		"""Get and store versions.

		Initialize attributes that store the Webware and WebKit versions as
		both tuples and strings. These are stored in the Properties.py files.

		"""
		from MiscUtils.PropertiesObject import PropertiesObject
		props = PropertiesObject(os.path.join(self.webwarePath(),
			'Properties.py'))
		self._webwareVersion = props['version']
		self._webwareVersionString = props['versionString']
		props = PropertiesObject(os.path.join(self.webKitPath(),
			'Properties.py'))
		self._webKitVersion = props['version']
		self._webKitVersionString = props['versionString']

	def taskManager(self):
		"""Accessor: `TaskKit.Scheduler` instance."""
		return self._taskManager

	def startSessionSweeper(self):
		"""Start session sweeper.

		Starts the session sweeper, `WebKit.Tasks.SessionTask`, which deletes
		session objects (and disk copies of those objects) that have expired.

		"""
		if self._sessionTimeout:
			tm = self.taskManager()
			if tm:
				from Tasks import SessionTask
				import time
				task = SessionTask.SessionTask(self._sessions)
				sweepinterval = self._sessionTimeout/10
				tm.addPeriodicAction(time.time() + sweepinterval,
					sweepinterval, task, "SessionSweeper")
				print "Session sweeper has started."

	def shutDown(self):
		"""Shut down the application.

		Called by AppServer when it is shuting down.  The `__del__` function
		of Application probably won't be called due to circular references.

		"""
		print "Application is shutting down..."
		self._running = 0
		self._sessions.storeAllSessions()
		if self._server.isPersistent():
			self.taskManager().stop()
		del self._sessions
		del self._server

		# Call all registered shutdown handlers
		for shutDownHandler in self._shutDownHandlers:
			shutDownHandler()
		del self._shutDownHandlers

		print "Application has been succesfully shutdown."

	def addShutDownHandler(self, func):
		"""Add a shutdown handler.

		Functions added through `addShutDownHandler` will be called when
		the AppServer is shutting down. You can use this hook to close
		database connections, clean up resources, save data to disk, etc.

		"""
		self._shutDownHandlers.append(func)


	## Config ##

	def defaultConfig(self):
		"""The default Application.config."""
		return defaultConfig # defined on the module level

	def configFilename(self):
		return self.serverSidePath('Configs/Application.config')

	def configReplacementValues(self):
		return self._server.configReplacementValues()


	## Versions ##

	def webwareVersion(self):
		"""Return the Webware version as a tuple."""
		return self._webwareVersion

	def webwareVersionString(self):
		"""Return the Webware version as a printable string."""
		return self._webwareVersionString

	def webKitVersion(self):
		""" Return the WebKit version as a tuple."""
		# @@ 2003-03 ib: This is synced with Webware now, should be removed
		# because redundant (and not that useful anyway)
		return self._webKitVersion

	def webKitVersionString(self):
		"""Return the WebKit version as a printable string."""
		return self._webKitVersionString


	## Sessions ##

	def session(self, sessionId, default=NoDefault):
		"""The session object for `sessionId`.

		Raises `KeyError` if session not found and no default is given.

		"""
		if default is NoDefault:
			return self._sessions[sessionId]
		else:
			return self._sessions.get(sessionId, default)

	def hasSession(self, sessionId):
		"""Check whether session `sessionId` exists."""
		return self._sessions.has_key(sessionId)

	def sessions(self):
		"""A dictionary of all the session objects."""
		return self._sessions

	def createSessionForTransaction(self, trans):
		"""Get the session object for the transaction.

		If the session already exists, returns that, otherwise creates
		a new session.

		Finding the session ID is done in `Transaction.sessionId`.

		"""
		debug = self.setting('Debug').get('Sessions')
		if debug:
			prefix = '>> [session] createSessionForTransaction:'
		sessId = trans.request().sessionId()
		if debug:
			print prefix, 'sessId =', sessId
		if sessId:
			try:
				session = self.session(sessId)
				if debug:
					print prefix, 'retrieved session =', session
			except KeyError:
				trans.request().setSessionExpired(1)
				if not self.setting('IgnoreInvalidSession'):
					raise HTTPSessionExpired
				sessId = None
		if not sessId:
			session = self._sessionClass(trans)
			self._sessions[session.identifier()] = session
			if debug:
				print prefix, 'created session =', session
		trans.setSession(session)
		return session

	def createSessionWithID(self, trans, sessionID):
		"""Create a session object with our session ID."""
		sess = self._sessionClass(trans, sessionID)
		# Replace the session if it didn't already exist,
		# otherwise we just throw it away.  setdefault is an atomic
		# operation so this guarantees that 2 different
		# copies of the session with the same ID never get placed into
		# the session store, even if multiple threads are calling
		# this method simultaneously.
		trans.application()._sessions.setdefault(sessionID, sess)

	def sessionTimeout(self, trans):
		"""Get the timeout (in seconds) for a user session.

		Overwrite to make this transaction dependent.

		"""
		return self._sessionTimeout

	def sessionPrefix(self, trans):
		"""Get the prefix string for the session ID.

		Overwrite to make this transaction dependent.

		"""
		return self._sessionPrefix

	def sessionName(self, trans):
		"""Get the name of the field holding the session ID.

		Overwrite to make this transaction dependent.

		"""
		return self._sessionName

	def sessionCookiePath(self, trans):
		"""Get the cookie path for this transaction.

		If not path is specified in the configuration setting,
		the servlet path is used for security reasons, see:
		http://www.net-security.org/dl/articles/cookie_path.pdf

		"""
		return self.setting('SessionCookiePath') or (
			trans.request().servletPath() + '/')


	## Misc Access ##

	def server(self):
		"""Acessor: the AppServer"""
		return self._server

	def serverSidePath(self, path=None):
		"""Get the server-side path.

		Returns the absolute server-side path of the WebKit application.
		If the optional path is passed in, then it is joined with the
		server side directory to form a path relative to the app server.

		"""
		if path:
			return os.path.normpath(
				os.path.join(self._serverSidePath, path))
		else:
			return self._serverSidePath

	def webwarePath(self):
		"""The path of the ``Webware/`` directory."""
		return self._server.webwarePath()

	def webKitPath(self):
		"""The Path of the ``Webware/WebKit/`` directory."""
		return self._server.webKitPath()

	def name(self):
		"""The name by which this was started. Usually `AppServer`."""
		# @@ 2003-03 ib: unconfirmed
		return sys.argv[0]


	## Activity Log ##

	def writeActivityLog(self, trans):
		"""Write an entry to the activity log.

		Writes an entry to the script log file. Uses settings
		``ActivityLogFilename`` and ``ActivityLogColumns``.

		"""
		filename = self.serverSidePath(
			self.setting('ActivityLogFilename'))
		if os.path.exists(filename):
			f = open(filename, 'a')
		else:
			f = open(filename, 'w')
			f.write(','.join(self.setting('ActivityLogColumns')) + '\n')
		values = []
		# We use UserDict on the next line because we know it inherits
		# NamedValueAccess and reponds to valueForName()
		objects = UserDict({
			'application': self,
			'transaction': trans,
			'request': trans.request(),
			'response': trans.response(),
			'servlet': trans.servlet(),
			'session': trans._session, # don't cause creation of session
		})
		for column in self.setting('ActivityLogColumns'):
			try:
				value = objects.valueForName(column)
			except Exception:
				value = '(unknown)'
			if type(value) is FloatType:
				# probably need more flexibility in the future
				value = '%0.2f' % value
			else:
				value = str(value)
			values.append(value)
		f.write(','.join(values) + '\n')
		f.close()
		for k in objects.keys():
			objects[k] = None


	## Request Dispatching ##

	# These are the entry points from `AppServer`, which take a raw request,
	# turn it into a transaction, run the transaction, and clean up.

	def dispatchRawRequest(self, requestDict, strmOut):
		"""Dispatch a raw request.

		Dispatch a request as passed from the Adapter through the AppServer.
		This method creates the request, response, and transaction object,
		then runs (via `runTransaction`) the transaction. It also catches any
		exceptions, which are then passed on to `handleExceptionInTransaction`.

		"""
		request = self.createRequestForDict(requestDict)
		if request:
			trans = Transaction(application=self, request=request)
			if trans:
				request.setTransaction(trans)
				response = request.responseClass()(trans, strmOut)
				if response:
					trans.setResponse(response)
					self.runTransaction(trans)
					try:
						trans.response().deliver()
					except ConnectionAbortedError, err:
						trans.setError(err)
					response.clearTransaction()
					# release possible servlets on the stack
					while 1:
						servlet = request.pop()
						if not servlet:
							break
						self.returnServlet(servlet)
						servlet.resetKeyBindings()
					# get current servlet (this may have changed)
					servlet = trans.servlet()
					if servlet:
						# return the current servlet to its pool
						self.returnServlet(servlet)
				if self.setting('LogActivity'):
					self.writeActivityLog(trans)
			request.clearTransaction()
		return trans

	def createRequestForDict(self, requestDict):
		"""Create request object for a given dictionary.

		Create a request object (subclass of `Request`) given the raw
		dictionary as passed by the adapter.

		The class of the request may be based on the contents of the
		dictionary (though only `HTTPRequest` is currently created),
		and the request will later determine the class of the response.

		Called by `dispatchRawRequest`.

		"""
		format = requestDict['format']
		# Maybe an EmailAdapter would make a request with a format of Email,
		# and an EmailRequest would be generated. For now just CGI/HTTPRequest.
		assert format == 'CGI'
		request = HTTPRequest(requestDict)
		# The request object is stored for tracking/debugging purposes.
		requestDict['requestObject'] = request
		return request

	def runTransaction(self, trans):
		"""Run transation.

		Executes the transaction, handling HTTPException errors.
		Finds the servlet (using the root parser, probably
		`URLParser.ContextParser`, to find the servlet for the
		transaction, then calling `runTransactionViaServlet`.

		Called by `dispatchRawRequest`.

		"""
		findServlet = self.rootURLParser().findServletForTransaction
		try:
			# remove the session identifier from the path
			self.removePathSession(trans)
			# determine the context and the servlet for the transaction
			servlet = findServlet(trans)
			# handle session field only now, because the name of the
			# session id field can depend on the context
			self.handlePathSession(trans)
			# now everything is set, run the transaction
			self.runTransactionViaServlet(servlet, trans)
		except EndResponse:
			pass
		except ConnectionAbortedError, err:
			trans.setError(err)
		except (KeyboardInterrupt, SystemExit):
			raise # do not catch these here
		except:
			# For once, we use a bare except here in order to catch
			# string and non standard exceptions from legacy code
			# (starting with Python 2.5 you can simply catch Exception;
			# KeyboardInterrupt, SystemExit will be excluded already
			# and string exceptions will output deprecation warnings).
			errClass, err = sys.exc_info()[:2]
			if not err: # string exception
				err, errClass = errClass, None
			urls = {}
			while 1:
				trans.setError(err)
				isHTTPException = isinstance(err, HTTPException)
				if isHTTPException:
					err.setTransaction(trans)
				if trans.response().isCommitted():
					# response already committed, cannot display error
					isHTTPException = False
					break
				if not self._errorPage:
					# no custom error page configured
					break
				# get custom error page for this exception
				url = errClass and self.errorPage(errClass)
				if isHTTPException and not url:
					# get custom error page for status code
					code = err.code()
					if self._errorPage.has_key(code):
						url = self._errorPage[code]
				if not url or urls.has_key(url):
					# If there is no custom error page configured,
					# or we get into a circular chain of error pages,
					# then we fall back to standard error handling.
					break
				urls[url] = None
				# forward to custom error page
				try:
					self.forward(trans, url)
				except EndResponse:
					pass
				except ConnectionAbortedError, err:
					trans.setError(err)
				except (KeyboardInterrupt, SystemExit):
					raise # do not catch these here
				except:
					# Once more, catch all other kinds of exceptions here.
					# If the custom error page itself throws an exception,
					# display the new exception instead of the original one,
					# so we notice that something is broken here.
					errClass, err = sys.exc_info()[:2]
					if not err: # string exception
						err, errClass = errClass, None
					url = None
				if url:
					return # error has already been handled
			if isHTTPException:
				# display standard http error page
				trans.response().displayError(err)
			else:
				# standard error handling
				if self.setting('EnterDebuggerOnException') \
						and sys.stdin.isatty():
					import pdb
					pdb.post_mortem(sys.exc_info()[2])
				self.handleExceptionInTransaction(
					sys.exc_info(), trans)

	def runTransactionViaServlet(self, servlet, trans):
		"""Execute the transaction using the servlet.

		This is the `awake`/`respond`/`sleep` sequence of calls, or if
		the servlet supports it, a single `runTransaction` call (which is
		presumed to make the awake/respond/sleep calls on its own). Using
		`runTransaction` allows the servlet to override the basic call
		sequence, or catch errors from that sequence.

		Called by `runTransaction`.

		"""
		trans.setServlet(servlet)
		if hasattr(servlet, 'runTransaction'):
			servlet.runTransaction(trans)
		else:
			# For backward compatibility (Servlet.runTransaction implements
			# this same sequence of calls, but by keeping it in the servlet
			# it's easier for the servlet to catch exceptions).
			try:
				trans.awake()
				trans.respond()
			finally:
				trans.sleep()

	def forward(self, trans, url):
		"""Forward the request to a different (internal) URL.

		The transaction's URL is changed to point to the new servlet,
		and the transaction is simply run again.

		Output is _not_ accumulated, so if the original servlet had any output,
		the new output will _replace_ the old output.

		You can change the request in place to control the servlet you are
		forwarding to -- using methods like `HTTPRequest.setField`.

		"""
		# Reset the response to a "blank slate"
		trans.response().reset()
		# Include the other servlet
		self.includeURL(trans, url)
		# Raise an exception to end processing of this request
		raise EndResponse

	def callMethodOfServlet(self, trans, url, method, *args, **kw):
		"""Call method of another servlet.

		Call a method of the servlet referred to by the URL. Calls sleep()
		and awake() before and after the method call. Or, if the servlet
		defines it, then `runMethodForTransaction` is used (analogous to the
		use of `runTransaction` in `forward`).

		The entire process is similar to `forward`, except that instead of
		`respond`, `method` is called (`method` should be a string, `*args`
		and `**kw` are passed as arguments to that method).

		"""
		# store current request and set the new URL
		request = trans.request()
		request.push(trans.servlet(),
			self.resolveInternalRelativePath(trans, url))
		# get new servlet
		servlet = self.rootURLParser().findServletForTransaction(trans)
		trans.setServlet(servlet)
		# call method of included servlet
		if hasattr(servlet, 'runMethodForTransaction'):
			result = servlet.runMethodForTransaction(
				trans, method, *args, **kw)
		else:
			servlet.awake(trans)
			result = getattr(servlet, method)(*args, **kw)
			servlet.sleep(trans)
		# return new servlet to its pool
		self.returnServlet(servlet)
		# release bindings of new servlet
		servlet.resetKeyBindings()
		# restore current request
		trans.setServlet(request.pop())
		return result

	def includeURL(self, trans, url):
		"""Include another servlet.

		Include the servlet given by the URL. Like `forward`,
		except control is ultimately returned to the servlet.

		"""
		# store current request and set the new URL
		request = trans.request()
		request.push(trans.servlet(),
			self.resolveInternalRelativePath(trans, url))
		# get new servlet
		servlet = self.rootURLParser().findServletForTransaction(trans)
		trans.setServlet(servlet)
		# run the included servlet
		try:
			servlet.runTransaction(trans)
		except EndResponse:
			# we interpret an EndResponse in an included page to mean
			# that the current page may continue processing
			pass
		# return new servlet to its pool
		self.returnServlet(servlet)
		# release bindings of new servlet
		servlet.resetKeyBindings()
		# restore current request
		trans.setServlet(request.pop())

	def resolveInternalRelativePath(self, trans, url):
		"""Return the absolute internal path.

		Given a URL, return the absolute internal URL.
		URLs are assumed relative to the current URL.
		Absolute paths are returned unchanged.

		"""
		if not url.startswith('/'):
			origDir = trans.request().urlPath()
			if not origDir.endswith('/'):
				origDir = os.path.dirname(origDir)
				if not origDir.endswith('/'):
					origDir += '/'
			url = origDir + url
		# deal with . and .. in the path
		parts = []
		for part in url.split('/'):
			if parts and part == '..':
				parts.pop()
			elif part != '.':
				parts.append(part)
		return '/'.join(parts)

	def returnServlet(self, servlet):
		"""Return the servlet to its pool."""
		servlet.close()

	def errorPage(self, errorClass):
		"""Get the error page url corresponding to an error class."""
		if self._errorPage.has_key(errorClass.__name__):
			return self._errorPage[errorClass.__name__]
		if errorClass is not Exception:
			for errorClass in errorClass.__bases__:
				url = self.errorPage(errorClass)
				if url:
					return url

	def handleException(self):
		"""Handle exceptions.

		This should only be used in cases where there is no transaction object,
		for example if an exception occurs when attempting to save a session
		to disk.

		"""
		self._exceptionHandlerClass(self, None, sys.exc_info())

	def handleExceptionInTransaction(self, excInfo, trans):
		"""Handle exception with info.

		Handles exception `excInfo` (as returned by `sys.exc_info()`)
		that was generated by `transaction`. It may display the exception
		report, email the report, etc., handled by
		`ExceptionHandler.ExceptionHandler`.

		"""
		request = trans.request()
		editlink = request.adapterName() + "/Admin/EditFile"
		self._exceptionHandlerClass(self, trans, excInfo,
			{"editlink": editlink})

	def rootURLParser(self):
		"""Accessor: the Rool URL parser.

		URL parsing (as defined	by subclasses of `URLParser.URLParser`)
		starts here. Other parsers are called in turn by this parser.

		"""
		return self._rootURLParser

	def hasContext(self, name):
		"""Checks whether context `name` exist."""
		return self._rootURLParser._contexts.has_key(name)

	def addContext(self, name, path):
		"""Add a context by named `name`, rooted at `path`.

		This gets imported as a package, and the last directory
		of `path` does not have to match the context name.
		(The package will be named `name`, regardless of `path`).

		Delegated to `URLParser.ContextParser`.

		"""
		self._rootURLParser.addContext(name, path)

	def addServletFactory(self, factory):
		"""Add a ServletFactory.

		Delegated to the `URLParser.ServletFactoryManager` singleton.

		"""
		URLParser.ServletFactoryManager.addServletFactory(factory)

	def contexts(self):
		"""Return a dictionary of context-name: context-path."""
		return self._rootURLParser._contexts

	def writeExceptionReport(self, handler):
		# @@ 2003-02 ib: does anyone care?
		pass

	def removePathSession(self, trans):
		"""Remove a possible session identifier from the path."""
		request = trans.request()
		# Try to get automatic path session:
		# If UseAutomaticPathSessions is enabled in Application.config,
		# Application redirects the browser to a URL with SID in path:
		# http://gandalf/a/_SID_=2001080221301877755/Examples/
		# The _SID_ part is extracted and removed from path here.
		# Note that We do not check for the exact name of the field
		# here because it may be context dependent.
		p = request._pathInfo
		if p:
			p = p.split('/', 2)
			if len(p) > 1 and not p[0] and '=' in p[1]:
				s = p[1]
				request._pathSID = s.split('=', 1)
				s += '/'
				del p[1]
				env = request.environ()
				request._pathInfo = env['PATH_INFO'] = '/'.join(p)
				for v in ('REQUEST_URI', 'PATH_TRANSLATED'):
					if env.has_key(v):
						env[v] = env[v].replace(s, '', 1)
			else:
				request._pathSID = None
		else:
			request._pathSID = None

	def handlePathSession(self, trans):
		"""Handle the session identifier that has been found in the path."""
		request = trans.request()
		if request._pathSID:
			sessionName = self.sessionName(trans)
			if request._pathSID[0] == sessionName:
				if request.hasCookie(sessionName):
					self.handleUnnecessaryPathSession(trans)
				request.cookies()[sessionName] = request._pathSID[1]
			else:
				if self._autoPathSessions:
					if not request.hasCookie(sessionName):
						self.handleMissingPathSession(trans)
		else:
			if self._autoPathSessions:
				if not request.hasCookie(self.sessionName(trans)):
					self.handleMissingPathSession(trans)

	def handleMissingPathSession(self, trans):
		"""Redirect requests without session info in the path.

		If UseAutomaticPathSessions is enabled in Application.config
		we redirect the browser to an absolute url with SID in path
		http://gandalf/a/_SID_=2001080221301877755/Examples/
		_SID_ is extracted and removed from path in HTTPRequest.py

		This is for convinient building of webapps that must not
		depend on cookie support.

		Note that we create an absolute URL with scheme and hostname
		because otherwise IIS will only cause an internal redirect.

		"""
		request = trans.request()
		url = '%s://%s%s/%s=%s%s%s%s' % (request.scheme(),
			request.hostAndPort(), request.servletPath(),
			self.sessionName(trans), trans.session().identifier(),
			request.pathInfo(), request.extraURLPath() or '',
			request.queryString() and '?' + request.queryString() or '')
		if self.setting('Debug')['Sessions']:
			print '>> [sessions] handling UseAutomaticPathSessions, ' \
				'redirecting to', url
		trans.response().sendRedirect(url)
		raise EndResponse

	def handleUnnecessaryPathSession(self, trans):
		"""Redirect request with unnecessary session info in the path.

		This is called if it has been determined that the request has a path
		session, but also cookies. In that case we redirect to eliminate the
		unnecessary path session.

		"""
		request = trans.request()
		url = '%s://%s%s%s%s%s' % (request.scheme(),
			request.hostAndPort(), request.servletPath(),
			request.pathInfo(), request.extraURLPath() or '',
			request.queryString() and '?' + request.queryString() or '')
		if self.setting('Debug')['Sessions']:
			print ">> [sessions] handling unnecessary path session, ' \
				'redirecting to", url
		trans.response().sendRedirect(url)
		raise EndResponse
