"""twisted server for CubicWeb web instances

:organization: Logilab
:copyright: 2001-2010 LOGILAB S.A. (Paris, FRANCE), license is LGPL v2.
:contact: http://www.logilab.fr/ -- mailto:contact@logilab.fr
:license: GNU Lesser General Public License, v2.1 - http://www.gnu.org/licenses
"""
__docformat__ = "restructuredtext en"

import sys
import os
import select
import errno
from time import mktime
from datetime import date, timedelta
from urlparse import urlsplit, urlunsplit
from cgi import FieldStorage, parse_header

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 ConfigurationError, CW_EVENT_MANAGER
from cubicweb.web import (AuthenticationError, NotFound, Redirect,
                          RemoteCallFailed, DirectResponse, StatusResponse,
                          ExplicitLogin)

from cubicweb.web.application import CubicWebPublisher

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):
        def setExpireHeader(response):
            # Don't provide additional resource information to error responses
            if response.code < 400:
                # the HTTP RFC recommands not going further than 1 year ahead
                expires = date.today() + timedelta(days=6*30)
                response.headers.setHeader('Expires', mktime(expires.timetuple()))
            return response
        d = maybeDeferred(super(LongTimeExpiringFile, self).render, request)
        return d.addCallback(setExpireHeader)


class CubicWebRootResource(resource.Resource):
    def __init__(self, config, debug=None):
        self.debugmode = debug
        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, debug=self.debugmode)
        self.base_url = config['base-url']
        self.https_url = config['https-url']
        self.versioned_datadir = 'data%s' % config.instance_md5_version()
        self.children = {}

    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):
        config = self.config
        interval = min(config['cleanup-session-time'] or 120,
                       config['cleanup-anonymous-session-time'] or 720) / 2.
        start_task(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.prePathURL()
        # XXX testing pre_path[0] not enough?
        if any(s in pre_path
               for s in (self.versioned_datadir, 'data', 'static')):
            # Anything in data/, static/ is treated as static files

            if 'static' in pre_path:
                # instance static directory
                datadir = self.config.static_directory
            elif 'fckeditor' in pre_path:
                fckeditordir = self.config.ext_resources['FCKEDITOR_PATH']
                return File(fckeditordir)
            else:
                # cube static data file
                datadir = self.config.locate_resource(path)
                if datadir is None:
                    return self
            self.info('static file %s from %s', path, datadir)
            if 'data' in pre_path:
                return File(os.path.join(datadir, path))
            else:
                return LongTimeExpiringFile(datadir)
        elif path == 'fckeditor':
            fckeditordir = self.config.ext_resources['FCKEDITOR_PATH']
            return File(fckeditordir)
        # 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.debugmode:
            self.appli.vreg.register_objects(self.config.vregistry_path())
        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):
        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 AuthenticationError:
            return self.request_auth(request=req)
        except Redirect, ex:
            return self.redirect(request=req, location=ex.location)
        if https and req.cnx.anonymous_connection:
            # 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 RemoteCallFailed, ex:
            req.set_header('content-type', 'application/json')
            return HTTPResponse(twisted_request=req._twreq, code=http.INTERNAL_SERVER_ERROR,
                                stream=ex.dumps(), headers=req.headers_out)
        except NotFound:
            result = self.appli.notfound_content(req)
            return HTTPResponse(twisted_request=req._twreq, code=http.NOT_FOUND,
                                stream=result, headers=req.headers_out)

        except ExplicitLogin:  # must be before AuthenticationError
            return self.request_auth(request=req)
        except AuthenticationError, ex:
            if self.config['auth-mode'] == 'cookie' and getattr(ex, 'url', None):
                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)

#TODO
# # XXX max upload size in the configuration

@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')
    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':
            self.content.seek(0,0)
            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
    self.process()


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

def run(config, debug):
    # create the site
    root_resource = CubicWebRootResource(config, debug)
    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)
    logger = getLogger('cubicweb.twisted')
    if not debug:
        if sys.platform == 'win32':
            raise ConfigurationError("Under windows, you must use the service management "
                                     "commands (e.g : 'net start my_instance)'")
        print 'instance starting in the background'
        if daemonize():
            return # child process
        if config['pid-file']:
            # ensure the directory where the pid-file should be set exists (for
            # instance /var/run/cubicweb may be deleted on computer restart)
            piddir = os.path.dirname(config['pid-file'])
            if not os.path.exists(piddir):
                os.makedirs(piddir)
            file(config['pid-file'], 'w').write(str(os.getpid()))
    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)
    if config['profile']:
        import cProfile
        cProfile.runctx('reactor.run()', globals(), locals(), config['profile'])
    else:
        reactor.run()