# copyright 2003-2013 LOGILAB S.A. (Paris, FRANCE), all rights reserved.

# contact http://www.logilab.fr/ -- mailto:contact@logilab.fr

#

# This file is part of CubicWeb.

#

# CubicWeb is free software: you can redistribute it and/or modify it under the

# terms of the GNU Lesser General Public License as published by the Free

# Software Foundation, either version 2.1 of the License, or (at your option)

# any later version.

#

# CubicWeb is distributed in the hope that it will be useful, but WITHOUT

# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS

# FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public License for more

# details.

#

# You should have received a copy of the GNU Lesser General Public License along

# with CubicWeb.  If not, see <http://www.gnu.org/licenses/>.

"""CubicWeb web client application object"""

__docformat__ = "restructuredtext en"

import sys

from time import clock, time

from contextlib import contextmanager

from warnings import warn

import httplib

from logilab.common.deprecation import deprecated

from rql import BadRQLQuery

from cubicweb import set_log_methods, cwvreg

from cubicweb import (

    ValidationError, Unauthorized, Forbidden,

    AuthenticationError, NoSelectableObject,

    BadConnectionId, CW_EVENT_MANAGER)

from cubicweb.dbapi import DBAPISession, anonymous_session

from cubicweb.web import LOGGER, component

from cubicweb.web import (

    StatusResponse, DirectResponse, Redirect, NotFound, LogOut,

    RemoteCallFailed, InvalidSession, RequestError)

from cubicweb.web.request import CubicWebRequestBase

# make session manager available through a global variable so the debug view can

# print information about web session

SESSION_MANAGER = None

@contextmanager

def anonymized_request(req):

    orig_session = req.session

    req.set_session(anonymous_session(req.vreg))

    try:

        yield req

    finally:

        req.set_session(orig_session)

class AbstractSessionManager(component.Component):

    """manage session data associated to a session identifier"""

    __regid__ = 'sessionmanager'

    def __init__(self, vreg):

        self.session_time = vreg.config['http-session-time'] or None

        self.authmanager = vreg['components'].select('authmanager', vreg=vreg)

        interval = (self.session_time or 0) / 2.

        if vreg.config.anonymous_user() is not None:

            self.cleanup_anon_session_time = vreg.config['cleanup-anonymous-session-time'] or 5 * 60

            assert self.cleanup_anon_session_time > 0

            if self.session_time is not None:

                self.cleanup_anon_session_time = min(self.session_time,

                                                     self.cleanup_anon_session_time)

            interval = self.cleanup_anon_session_time / 2.

        # we don't want to check session more than once every 5 minutes

        self.clean_sessions_interval = max(5 * 60, interval)

    def clean_sessions(self):

        """cleanup sessions which has not been unused since a given amount of

        time. Return the number of sessions which have been closed.

        """

        self.debug('cleaning http sessions')

        session_time = self.session_time

        closed, total = 0, 0

        for session in self.current_sessions():

            total += 1

            try:

                last_usage_time = session.cnx.check()

            except AttributeError:

                last_usage_time = session.mtime

            except BadConnectionId:

                self.close_session(session)

                closed += 1

            else:

                no_use_time = (time() - last_usage_time)

                if session.anonymous_session:

                    if no_use_time >= self.cleanup_anon_session_time:

                        self.close_session(session)

                        closed += 1

                elif session_time is not None and no_use_time >= session_time:

                    self.close_session(session)

                    closed += 1

        return closed, total - closed

    def current_sessions(self):

        """return currently open sessions"""

        raise NotImplementedError()

    def get_session(self, req, sessionid):

        """return existing session for the given session identifier"""

        raise NotImplementedError()

    def open_session(self, req):

        """open and return a new session for the given request. The session is

        also bound to the request.

        raise :exc:`cubicweb.AuthenticationError` if authentication failed

        (no authentication info found or wrong user/password)

        """

        raise NotImplementedError()

    def close_session(self, session):

        """close session on logout or on invalid session detected (expired out,

        corrupted...)

        """

        raise NotImplementedError()

class AbstractAuthenticationManager(component.Component):

    """authenticate user associated to a request and check session validity"""

    __regid__ = 'authmanager'

    def __init__(self, vreg):

        self.vreg = vreg

    def validate_session(self, req, session):

        """check session validity, reconnecting it to the repository if the

        associated connection expired in the repository side (hence the

        necessity for this method).

        raise :exc:`InvalidSession` if session is corrupted for a reason or

        another and should be closed

        """

        raise NotImplementedError()

    def authenticate(self, req):

        """authenticate user using connection information found in the request,

        and return corresponding a :class:`~cubicweb.dbapi.Connection` instance,

        as well as login and authentication information dictionary used to open

        the connection.

        raise :exc:`cubicweb.AuthenticationError` if authentication failed

        (no authentication info found or wrong user/password)

        """

        raise NotImplementedError()

class CookieSessionHandler(object):

    """a session handler using a cookie to store the session identifier"""

    def __init__(self, appli):

        self.vreg = appli.vreg

        self.session_manager = self.vreg['components'].select('sessionmanager',

                                                              vreg=self.vreg)

        global SESSION_MANAGER

        SESSION_MANAGER = self.session_manager

        if self.vreg.config.mode != 'test':

            # don't try to reset session manager during test, this leads to

            # weird failures when running multiple tests

            CW_EVENT_MANAGER.bind('after-registry-reload',

                                  self.reset_session_manager)

    def reset_session_manager(self):

        data = self.session_manager.dump_data()

        self.session_manager = self.vreg['components'].select('sessionmanager',

                                                              vreg=self.vreg)

        self.session_manager.restore_data(data)

        global SESSION_MANAGER

        SESSION_MANAGER = self.session_manager

    @property

    def clean_sessions_interval(self):

        return self.session_manager.clean_sessions_interval

    def clean_sessions(self):

        """cleanup sessions which has not been unused since a given amount of

        time

        """

        self.session_manager.clean_sessions()

    def session_cookie(self, req):

        """return a string giving the name of the cookie used to store the

        session identifier.

        """

        if req.https:

            return '__%s_https_session' % self.vreg.config.appid

        return '__%s_session' % self.vreg.config.appid

    def set_session(self, req):

        """associate a session to the request

        Session id is searched from :

        - # form variable

        - cookie

        if no session id is found, open a new session for the connected user

        or request authentification as needed

        :raise Redirect: if authentication has occurred and succeed

        """

        cookie = req.get_cookie()

        sessioncookie = self.session_cookie(req)

        try:

            sessionid = str(cookie[sessioncookie].value)

        except KeyError: # no session cookie

            session = self.open_session(req)

        else:

            try:

                session = self.get_session(req, sessionid)

            except InvalidSession:

                # try to open a new session, so we get an anonymous session if

                # allowed

                session = self.open_session(req)

            else:

                if not session.cnx:

                    # session exists but is not bound to a connection. We should

                    # try to authenticate

                    loginsucceed = False

                    try:

                        if self.open_session(req, allow_no_cnx=False):

                            loginsucceed = True

                    except Redirect:

                        # may be raised in open_session (by postlogin mechanism)

                        # on successful connection

                        loginsucceed = True

                        raise

                    except AuthenticationError:

                        # authentication failed, continue to use this session

                        req.set_session(session)

                    finally:

                        if loginsucceed:

                            # session should be replaced by new session created

                            # in open_session

                            self.session_manager.close_session(session)

    def get_session(self, req, sessionid):

        session = self.session_manager.get_session(req, sessionid)

        session.mtime = time()

        return session

    def open_session(self, req, allow_no_cnx=True):

        session = self.session_manager.open_session(req, allow_no_cnx=allow_no_cnx)

        sessioncookie = self.session_cookie(req)

        secure = req.https and req.base_url().startswith('https://')

        req.set_cookie(sessioncookie, session.sessionid,

                       maxage=None, secure=secure)

        if not session.anonymous_session:

            self.session_manager.postlogin(req)

        return session

    def logout(self, req, goto_url):

        """logout from the instance by cleaning the session and raising

        `AuthenticationError`

        """

        self.session_manager.close_session(req.session)

        req.remove_cookie(self.session_cookie(req))

        raise LogOut(url=goto_url)

    # these are overridden by set_log_methods below

    # only defining here to prevent pylint from complaining

    info = warning = error = critical = exception = debug = lambda msg,*a,**kw: None

class CubicWebPublisher(object):

    """the publisher is a singleton hold by the web frontend, and is responsible

    to publish HTTP request.

    The http server will call its main entry point ``application.handle_request``.

    .. automethod:: cubicweb.web.application.CubicWebPublisher.main_handle_request

    """

    def __init__(self, config,

                 session_handler_fact=CookieSessionHandler,

                 vreg=None):

        self.info('starting web instance from %s', config.apphome)

        if vreg is None:

            vreg = cwvreg.CWRegistryStore(config)

        self.vreg = vreg

        # connect to the repository and get instance's schema

        self.repo = config.repository(vreg)

        if not vreg.initialized:

            config.init_cubes(self.repo.get_cubes())

            vreg.init_properties(self.repo.properties())

            vreg.set_schema(self.repo.get_schema())

        # set the correct publish method

        if config['query-log-file']:

            from threading import Lock

            self._query_log = open(config['query-log-file'], 'a')

            self.handle_request = self.log_handle_request

            self._logfile_lock = Lock()

        else:

            self._query_log = None

            self.handle_request = self.main_handle_request

        # instantiate session and url resolving helpers

        self.session_handler = session_handler_fact(self)

        self.set_urlresolver()

        CW_EVENT_MANAGER.bind('after-registry-reload', self.set_urlresolver)

    def set_urlresolver(self):

        self.url_resolver = self.vreg['components'].select('urlpublisher',

                                                           vreg=self.vreg)

    def connect(self, req):

        """return a connection for a logged user object according to existing

        sessions (i.e. a new connection may be created or an already existing

        one may be reused

        """

        self.session_handler.set_session(req)

    # publish methods #########################################################

    def log_handle_request(self, req, path):

        """wrapper around _publish to log all queries executed for a given

        accessed path

        """

        try:

            return self.main_handle_request(req, path)

        finally:

            cnx = req.cnx

            if cnx:

                with self._logfile_lock:

                    try:

                        result = ['\n'+'*'*80]

                        result.append(req.url())

                        result += ['%s %s -- (%.3f sec, %.3f CPU sec)' % q

                                   for q in cnx.executed_queries]

                        cnx.executed_queries = []

                        self._query_log.write('\n'.join(result).encode(req.encoding))

                        self._query_log.flush()

                    except Exception:

                        self.exception('error while logging queries')

    def main_handle_request(self, req, path):

        """Process an http request

        Arguments are:

        - a Request object

        - path of the request object

        It returns the content of the http response. HTTP header and status are

        set on the Request object.

        """

        if not isinstance(req, CubicWebRequestBase):

            warn('[3.15] Application entry point arguments are now (req, path) '

                 'not (path, req)', DeprecationWarning, 2)

            req, path = path, req

        if req.authmode == 'http':

            # activate realm-based auth

            realm = self.vreg.config['realm']

            req.set_header('WWW-Authenticate', [('Basic', {'realm' : realm })], raw=False)

        content = ''

        try:

            self.connect(req)

            # DENY https acces for anonymous_user

            if (req.https

                and req.session.anonymous_session

                and self.vreg.config['https-deny-anonymous']):

                # don't allow anonymous on https connection

                raise AuthenticationError()

            # nested try to allow LogOut to delegate logic to AuthenticationError

            # handler

            try:

                ### Try to generate the actual request content

                content = self.core_handle(req, path)

            # Handle user log-out

            except LogOut as ex:

                # When authentification is handled by cookie the code that

                # raised LogOut must has invalidated the cookie. We can just

                # reload the original url without authentification

                if self.vreg.config['auth-mode'] == 'cookie' and ex.url:

                    req.headers_out.setHeader('location', str(ex.url))

                if ex.status is not None:

                    req.status_out = httplib.SEE_OTHER

                # When the authentification is handled by http we must

                # explicitly ask for authentification to flush current http

                # authentification information

                else:

                    # Render "logged out" content.

                    # assignement to ``content`` prevent standard

                    # AuthenticationError code to overwrite it.

                    content = self.loggedout_content(req)

                    # let the explicitly reset http credential

                    raise AuthenticationError()