"""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 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 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.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):
    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.children = {}
        self.static_directories = set(('data%s' % config.instance_md5_version(),
                                       'data', 'static', 'fckeditor'))
    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.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:
            if path == directory: # recurse
                return self
            cls = File
            if directory == 'static':
                datadir = self.config.static_directory
            elif directory == 'fckeditor':
                datadir = self.config.ext_resources['FCKEDITOR_PATH']
            else:
                datadir = self.config.locate_resource(path)
                if datadir is None:
                    return self
                if directory != 'data':
                    # versioned directory, use specific file with http cache
                    # headers so their are cached for a very long time
                    cls = LongTimeExpiringFile
            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.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 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)

#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()