# copyright 2003-2014 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.repoapi import anonymous_cnx

from cubicweb.web import LOGGER, component, cors

from cubicweb.web import (

    StatusResponse, DirectResponse, Redirect, NotFound, LogOut,

    RemoteCallFailed, InvalidSession, RequestError, PublishException)

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_cnx = req.cnx

    anon_clt_cnx = anonymous_cnx(orig_cnx._session.repo)

    req.set_cnx(anon_clt_cnx)

    try:

        with anon_clt_cnx:

            yield req

    finally:

        req.set_cnx(orig_cnx)

class AbstractSessionManager(component.Component):

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

    __regid__ = 'sessionmanager'

    def __init__(self, repo):

        vreg = repo.vreg

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

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

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

        if vreg.config.anonymous_user()[0] 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.

        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, repo):

        self.vreg = repo.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.repo = appli.repo

        self.vreg = appli.vreg

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

                                                              repo=self.repo)

        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',

                                                              repo=self.repo)

        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 get_session(self, req):

        """Return a session object corresponding to credentials held by the req

        Session id is searched from :

        - # form variable

        - cookie

        If no session id is found, try opening a new session with credentials

        found in the request.

        Raises AuthenticationError if no session can be found or created.

        """

        cookie = req.get_cookie()

        sessioncookie = self.session_cookie(req)

        try:

            sessionid = str(cookie[sessioncookie].value)

            session = self.get_session_by_id(req, sessionid)

        except (KeyError, InvalidSession): # no valid session cookie

            session = self.open_session(req)

        return session

    def get_session_by_id(self, req, sessionid):

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

        session.mtime = time()

        return session

    def open_session(self, req):

        session = self.session_manager.open_session(req)

        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, session)

        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

    You have to provide both a repository and web-server config at

    initialization. In all in one instance both config will be the same.

    """

    def __init__(self, repo, config, session_handler_fact=CookieSessionHandler):

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

        self.repo = repo

        self.vreg = repo.vreg

        # get instance's schema

        if not self.vreg.initialized:

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

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

            self.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 get_session(self, req):

        """Return a session object corresponding to credentials held by the req

        May raise AuthenticationError.

        """

        return self.session_handler.get_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:

            try:

                session = self.get_session(req)

                from  cubicweb import repoapi

                cnx = repoapi.ClientConnection(session)

                req.set_cnx(cnx)

            except AuthenticationError:

                # Keep the dummy session set at initialisation.

                # such session with work to an some extend but raise an

                # AuthenticationError on any database access.

                import contextlib

                @contextlib.contextmanager

                def dummy():

                    yield

                cnx = dummy()

                # XXX We want to clean up this approach in the future. But

                # several cubes like registration or forgotten password rely on

                # this principle.

            # 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

                with cnx:

                    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()

        except Redirect as ex:

            # authentication needs redirection (eg openid)

            content = self.redirect_handler(req, ex)