# copyright 2003-2010 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/>.

"""twisted server for CubicWeb web instances

"""

__docformat__ = "restructuredtext en"

import sys

import os

import select

import errno

import traceback

from os.path import join

from time import mktime

from datetime import date, timedelta

from urlparse import urlsplit, urlunsplit

from cgi import FieldStorage, parse_header

from cStringIO import StringIO

from twisted.internet import reactor, task, threads

from twisted.internet.defer import maybeDeferred

from twisted.web import http, server

from twisted.web import static, resource

from twisted.web.server import NOT_DONE_YET

from simplejson import dumps

from logilab.common.decorators import monkeypatch

from cubicweb import AuthenticationError, ConfigurationError, CW_EVENT_MANAGER

from cubicweb.web import Redirect, DirectResponse, StatusResponse, LogOut

from cubicweb.web.application import CubicWebPublisher

from cubicweb.web.http_headers import generateDateTime

from cubicweb.etwist.request import CubicWebTwistedRequestAdapter

from cubicweb.etwist.http import HTTPResponse

def daemonize():

    # XXX unix specific

    # XXX factorize w/ code in cw.server.server and cw.server.serverctl

    # (start-repository command)

    # See http://www.erlenstar.demon.co.uk/unix/faq_toc.html#TOC16

    if os.fork():   # launch child and...

        return 1

    os.setsid()

    if os.fork():   # launch child again.

        return 1

    # move to the root to avoit mount pb

    os.chdir('/')

    # set paranoid umask

    os.umask(077)

    null = os.open('/dev/null', os.O_RDWR)

    for i in range(3):

        try:

            os.dup2(null, i)

        except OSError, e:

            if e.errno != errno.EBADF:

                raise

    os.close(null)

    return None

def start_task(interval, func):

    lc = task.LoopingCall(func)

    # wait until interval has expired to actually start the task, else we have

    # to wait all task to be finished for the server to be actually started

    lc.start(interval, now=False)

def host_prefixed_baseurl(baseurl, host):

    scheme, netloc, url, query, fragment = urlsplit(baseurl)

    netloc_domain = '.' + '.'.join(netloc.split('.')[-2:])

    if host.endswith(netloc_domain):

        netloc = host

    baseurl = urlunsplit((scheme, netloc, url, query, fragment))

    return baseurl

class ForbiddenDirectoryLister(resource.Resource):

    def render(self, request):

        return HTTPResponse(twisted_request=request,

                            code=http.FORBIDDEN,

                            stream='Access forbidden')

class File(static.File):

    """Prevent from listing directories"""

    def directoryListing(self):

        return ForbiddenDirectoryLister()

class LongTimeExpiringFile(File):

    """overrides static.File and sets a far future ``Expires`` date

    on the resouce.

    versions handling is done by serving static files by different

    URLs for each version. For instance::

      http://localhost:8080/data-2.48.2/cubicweb.css

      http://localhost:8080/data-2.49.0/cubicweb.css

      etc.

    """

    def render(self, request):

        # XXX: Don't provide additional resource information to error responses

        #

        # the HTTP RFC recommands not going further than 1 year ahead

        expires = date.today() + timedelta(days=6*30)

        request.setHeader('Expires', generateDateTime(mktime(expires.timetuple())))

        return File.render(self, request)

class CubicWebRootResource(resource.Resource):

        self.config = config

        # instantiate publisher here and not in init_publisher to get some

        # checks done before daemonization (eg versions consistency)

        self.base_url = config['base-url']

        self.https_url = config['https-url']

        self.children = {}

        self.static_directories = set(('data%s' % config.instance_md5_version(),

                                       'data', 'static', 'fckeditor'))

        global MAX_POST_LENGTH

        MAX_POST_LENGTH = config['max-post-length']

    def init_publisher(self):

        config = self.config

        # when we have an in-memory repository, clean unused sessions every XX

        # seconds and properly shutdown the server

        if config.repo_method == 'inmemory':

            reactor.addSystemEventTrigger('before', 'shutdown',

                                          self.shutdown_event)

            if config.pyro_enabled():

                # if pyro is enabled, we have to register to the pyro name

                # server, create a pyro daemon, and create a task to handle pyro

                # requests

                self.pyro_daemon = self.appli.repo.pyro_register()

                self.pyro_listen_timeout = 0.02

                self.appli.repo.looping_task(1, self.pyro_loop_event)

            self.appli.repo.start_looping_tasks()

        self.set_url_rewriter()

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

    def start_service(self):

        start_task(self.appli.session_handler.clean_sessions_interval,

                   self.appli.session_handler.clean_sessions)

    def set_url_rewriter(self):

        self.url_rewriter = self.appli.vreg['components'].select_or_none('urlrewriter')

    def shutdown_event(self):

        """callback fired when the server is shutting down to properly

        clean opened sessions

        """

        self.appli.repo.shutdown()

    def pyro_loop_event(self):

        """listen for pyro events"""

        try:

            self.pyro_daemon.handleRequests(self.pyro_listen_timeout)

        except select.error:

            return

    def getChild(self, path, request):

        """Indicate which resource to use to process down the URL's path"""

        pre_path = request.path.split('/')[1:]

        if pre_path[0] == 'https':

            pre_path.pop(0)

        directory = pre_path[0]

        # Anything in data/, static/, fckeditor/ and the generated versioned

        # data directory is treated as static files

        if directory in self.static_directories:

            # take care fckeditor may appears as root directory or as a data

            # subdirectory

            if directory == 'static':

                return File(self.config.static_directory)

            if directory == 'fckeditor':

                return File(self.config.ext_resources['FCKEDITOR_PATH'])

            if directory != 'data':

                # versioned directory, use specific file with http cache

                # headers so their are cached for a very long time

                cls = LongTimeExpiringFile

            else:

                cls = File

            if path == 'fckeditor':

                return cls(self.config.ext_resources['FCKEDITOR_PATH'])

            if path == directory: # recurse

                return self

            datadir = self.config.locate_resource(path)

            if datadir is None:

                return self # recurse

            self.debug('static file %s from %s', path, datadir)

            return cls(join(datadir, path))

        # Otherwise we use this single resource

        return self

    def render(self, request):

        """Render a page from the root resource"""

        # reload modified files in debug mode

            self.appli.vreg.reload_if_needed()

        if self.config['profile']: # default profiler don't trace threads

            return self.render_request(request)

        else:

            deferred = threads.deferToThread(self.render_request, request)

            return NOT_DONE_YET

    def render_request(self, request):

        try:

            return self._render_request(request)

        except:

            errorstream = StringIO()

            traceback.print_exc(file=errorstream)

            return HTTPResponse(stream='<pre>%s</pre>' % errorstream.getvalue(),

                                code=500, twisted_request=request)

    def _render_request(self, request):

        origpath = request.path

        host = request.host

        # dual http/https access handling: expect a rewrite rule to prepend

        # 'https' to the path to detect https access

        if origpath.split('/', 2)[1] == 'https':

            origpath = origpath[6:]

            request.uri = request.uri[6:]

            https = True

            baseurl = self.https_url or self.base_url

        else:

            https = False

            baseurl = self.base_url

        if self.config['use-request-subdomain']:

            baseurl = host_prefixed_baseurl(baseurl, host)

            self.warning('used baseurl is %s for this request', baseurl)

        req = CubicWebTwistedRequestAdapter(request, self.appli.vreg, https, baseurl)

        if req.authmode == 'http':

            # activate realm-based auth

            realm = self.config['realm']

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

        try:

            self.appli.connect(req)

        except Redirect, ex:

            return self.redirect(request=req, location=ex.location)

        if https and req.session.anonymous_session:

            # don't allow anonymous on https connection

            return self.request_auth(request=req)

        if self.url_rewriter is not None:

            # XXX should occur before authentication?

            try:

                path = self.url_rewriter.rewrite(host, origpath, req)

            except Redirect, ex:

                return self.redirect(req, ex.location)

            request.uri.replace(origpath, path, 1)

        else:

            path = origpath

        if not path or path == "/":

            path = 'view'

        try:

            result = self.appli.publish(path, req)

        except DirectResponse, ex:

            return ex.response

        except StatusResponse, ex:

            return HTTPResponse(stream=ex.content, code=ex.status,

                                twisted_request=req._twreq,

                                headers=req.headers_out)

        except AuthenticationError:

            return self.request_auth(request=req)

        except LogOut, ex:

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

                return self.redirect(request=req, location=ex.url)

            # in http we have to request auth to flush current http auth

            # information

            return self.request_auth(request=req, loggedout=True)

        except Redirect, ex:

            return self.redirect(request=req, location=ex.location)

        # request may be referenced by "onetime callback", so clear its entity

        # cache to avoid memory usage

        req.drop_entity_cache()

        return HTTPResponse(twisted_request=req._twreq, code=http.OK,

                            stream=result, headers=req.headers_out)

    def redirect(self, request, location):

        self.debug('redirecting to %s', str(location))

        request.headers_out.setHeader('location', str(location))

        # 303 See other

        return HTTPResponse(twisted_request=request._twreq, code=303,

                            headers=request.headers_out)

    def request_auth(self, request, loggedout=False):

        if self.https_url and request.base_url() != self.https_url:

            return self.redirect(request, self.https_url + 'login')

        if self.config['auth-mode'] == 'http':

            code = http.UNAUTHORIZED

        else:

            code = http.FORBIDDEN

        if loggedout:

            if request.https:

                request._base_url =  self.base_url

                request.https = False

            content = self.appli.loggedout_content(request)

        else:

            content = self.appli.need_login_content(request)

        return HTTPResponse(twisted_request=request._twreq,

                            stream=content, code=code,

                            headers=request.headers_out)

JSON_PATHS = set(('json',))

FRAME_POST_PATHS = set(('validateform',))

orig_gotLength = http.Request.gotLength

@monkeypatch(http.Request)

def gotLength(self, length):

    orig_gotLength(self, length)

    if length > MAX_POST_LENGTH: # length is 0 on GET

        path = self.channel._path.split('?', 1)[0].rstrip('/').rsplit('/', 1)[-1]

        self.clientproto = 'HTTP/1.1' # not yet initialized

        self.channel.persistent = 0   # force connection close on cleanup

        self.setResponseCode(http.BAD_REQUEST)

        if path in JSON_PATHS: # XXX better json path detection

            self.setHeader('content-type',"application/json")

            body = dumps({'reason': 'request max size exceeded'})

        elif path in FRAME_POST_PATHS: # XXX better frame post path detection

            self.setHeader('content-type',"text/html")

            body = ('<script type="text/javascript">'

                    'window.parent.handleFormValidationResponse(null, null, null, %s, null);'

                    '</script>' % dumps( (False, 'request max size exceeded', None) ))

        else:

            self.setHeader('content-type',"text/html")

            body = ("<html><head><title>Processing Failed</title></head><body>"

                    "<b>request max size exceeded</b></body></html>")

        self.setHeader('content-length', str(len(body)))

        self.write(body)

        # see request.finish(). Done here since we get error due to not full

        # initialized request

        self.finished = 1

        if not self.queued:

            self._cleanup()

        for d in self.notifications:

            d.callback(None)

        self.notifications = []

@monkeypatch(http.Request)

def requestReceived(self, command, path, version):

    """Called by channel when all data has been received.

    This method is not intended for users.

    """

    self.content.seek(0, 0)

    self.args = {}

    self.files = {}

    self.stack = []

    self.method, self.uri = command, path

    self.clientproto = version

    x = self.uri.split('?', 1)

    if len(x) == 1:

        self.path = self.uri

    else:

        self.path, argstring = x

        self.args = http.parse_qs(argstring, 1)

    # cache the client and server information, we'll need this later to be

    # serialized and sent with the request so CGIs will work remotely

    self.client = self.channel.transport.getPeer()