# copyright 2003-2012 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 select

import traceback

import threading

from urlparse import urlsplit, urlunsplit

from cgi import FieldStorage, parse_header

from cubicweb.statsd_logger import statsd_timeit

from twisted.internet import reactor, task, threads

from twisted.web import http, server

from twisted.web import resource

from twisted.web.server import NOT_DONE_YET

from logilab.mtconverter import xml_escape

from logilab.common.decorators import monkeypatch

from cubicweb import ConfigurationError, CW_EVENT_MANAGER

from cubicweb.utils import json_dumps

from cubicweb.web import DirectResponse

from cubicweb.web.application import CubicWebPublisher

from cubicweb.etwist.request import CubicWebTwistedRequestAdapter

from cubicweb.etwist.http import HTTPResponse

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 tasks to be finished for the server to be actually started

    lc.start(interval, now=False)

class CubicWebRootResource(resource.Resource):

    def __init__(self, config, repo):

        resource.Resource.__init__(self)

        self.config = config

        # instantiate publisher here and not in init_publisher to get some

        # checks done before daemonization (eg versions consistency)

        self.appli = CubicWebPublisher(repo, config)

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

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

        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['repository-uri'] == 'inmemory://':

            if config.mode != 'test':

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

                                              self.shutdown_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 getChild(self, path, request):

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

        return self

    def render(self, request):

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

        # reload modified files in debug mode

        if self.config.debugmode:

            self.config.uiprops.reload_if_needed()

            if self.https_url:

                self.config.https_uiprops.reload_if_needed()

            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

    @statsd_timeit

    def render_request(self, request):

        try:

            # processing HUGE files (hundred of megabytes) in http.processReceived

            # blocks other HTTP requests processing

            # due to the clumsy & slow parsing algorithm of cgi.FieldStorage

            # so we deferred that part to the cubicweb thread

            request.process_multipart()

            return self._render_request(request)

        except Exception:

            trace = traceback.format_exc()

            return HTTPResponse(stream='<pre>%s</pre>' % xml_escape(trace),

                                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

        https = False

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

            origpath = origpath[6:]

            request.uri = request.uri[6:]

            https = True

        if self.url_rewriter is not None:

            # XXX should occur before authentication?

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

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

        else:

            path = origpath

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

        try:

            ### Try to generate the actual request content

            content = self.appli.handle_request(req, path)

        except DirectResponse as ex:

            return ex.response

        # at last: create twisted object

        return HTTPResponse(code    = req.status_out,

                            headers = req.headers_out,

                            stream  = content,

                            twisted_request=req._twreq)

    # these are overridden by set_log_methods below

    # only defining here to prevent pylint from complaining

    @classmethod

    def debug(cls, msg, *a, **kw):

        pass

    info = warning = error = critical = exception = debug

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.REQUEST_ENTITY_TOO_LARGE)

        if path in JSON_PATHS: # XXX better json path detection

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

            body = json_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>' % json_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()

    self.host = self.channel.transport.getHost()

    # Argument processing

    ctype = self.getHeader('content-type')

    self._do_process_multipart = False

    if self.method == "POST" and ctype:

        key, pdict = parse_header(ctype)

        if key == 'application/x-www-form-urlencoded':

            self.args.update(http.parse_qs(self.content.read(), 1))

            self.content.seek(0)

        elif key == 'multipart/form-data':

            # defer this as it can be extremely time consumming

            # with big files

            self._do_process_multipart = True

    self.process()

@monkeypatch(http.Request)

def process_multipart(self):

    if not self._do_process_multipart:

        return

    form = FieldStorage(self.content, self.received_headers,

                        environ={'REQUEST_METHOD': 'POST'},

                        keep_blank_values=1,

                        strict_parsing=1)

    for key in form:

        values = form[key]

        if not isinstance(values, list):

            values = [values]

        for value in values:

            if value.filename:

                if value.done != -1: # -1 is transfer has been interrupted

                    self.files.setdefault(key, []).append((value.filename, value.file))

                else:

                    self.files.setdefault(key, []).append((None, None))

            else:

                self.args.setdefault(key, []).append(value.value)

from logging import getLogger

from cubicweb import set_log_methods

LOGGER = getLogger('cubicweb.twisted')

set_log_methods(CubicWebRootResource, LOGGER)

def run(config, debug=None, repo=None):

    # repo may by passed during test.

    #

    # Test has already created a repo object so we should not create a new one.

    # Explicitly passing the repo object avoid relying on the fragile

    # config.repository() cache. We could imagine making repo a mandatory

    # argument and receives it from the starting command directly.

    if debug is not None:

        config.debugmode = debug

    config.check_writeable_uid_directory(config.appdatahome)

    # create the site

    if repo is None:

        repo = config.repository()

    root_resource = CubicWebRootResource(config, repo)

    website = server.Site(root_resource)

    # serve it via standard HTTP on port set in the configuration

    port = config['port'] or 8080

    interface = config['interface']

    reactor.suggestThreadPoolSize(config['webserver-threadpool-size'])

    reactor.listenTCP(port, website, interface=interface)

    if not config.debugmode:

        if sys.platform == 'win32':

            raise ConfigurationError("Under windows, you must use the service management "

                                     "commands (e.g : 'net start my_instance)'")

        from logilab.common.daemon import daemonize

        LOGGER.info('instance started in the background on %s', root_resource.base_url)

        whichproc = daemonize(config['pid-file'], umask=config['umask'])

        if whichproc: # 1 = orig process, 2 = first fork, None = second fork (eg daemon process)

            return whichproc # parent process

    root_resource.init_publisher() # before changing uid

    if config['uid'] is not None:

        from logilab.common.daemon import setugid

        setugid(config['uid'])

    root_resource.start_service()

    LOGGER.info('instance started on %s', root_resource.base_url)

    # avoid annoying warnign if not in Main Thread

    signals = threading.currentThread().getName() == 'MainThread'

    if config['profile']:

        import cProfile

        cProfile.runctx('reactor.run(installSignalHandlers=%s)' % signals,

                        globals(), locals(), config['profile'])

    else:

        reactor.run(installSignalHandlers=signals)