# 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
import threading
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 logilab.common.decorators import monkeypatch

from cubicweb import AuthenticationError, ConfigurationError, CW_EVENT_MANAGER
from cubicweb.utils import json_dumps
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 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):
    def __init__(self, config, vreg=None):
        self.config = config
        # instantiate publisher here and not in init_publisher to get some
        # checks done before daemonization (eg versions consistency)
        self.appli = CubicWebPublisher(config, vreg=vreg)
        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':
            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)
            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 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)
            uiprops = self.config.https_uiprops
        else:
            uiprops = self.config.uiprops
        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(uiprops['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(uiprops['FCKEDITOR_PATH'])
            if path == directory: # recurse
                return self
            datadir, path = 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
        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

    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:
            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 = 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))
        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:
        value = form[key]
        if isinstance(value, list):
            self.args[key] = [v.value for v in value]
        elif value.filename:
            if value.done != -1: # -1 is transfer has been interrupted
                self.files[key] = (value.filename, value.file)
            else:
                self.files[key] = (None, None)
        else:
            self.args[key] = value.value

from logging import getLogger
from cubicweb import set_log_methods
LOGGER = getLogger('cubicweb.twisted')
set_log_methods(CubicWebRootResource, LOGGER)

def run(config, vreg=None, debug=None):
    if debug is not None:
        config.debugmode = debug
    config.check_writeable_uid_directory(config.appdatahome)
    # create the site
    root_resource = CubicWebRootResource(config, vreg=vreg)
    website = server.Site(root_resource)
    # serve it via standard HTTP on port set in the configuration
    port = config['port'] or 8080
    reactor.listenTCP(port, website)
    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)
        if daemonize(config['pid-file']):
            return # child process
    root_resource.init_publisher() # before changing uid
    if config['uid'] is not None:
        try:
            uid = int(config['uid'])
        except ValueError:
            from pwd import getpwnam
            uid = getpwnam(config['uid']).pw_uid
        os.setuid(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)