"""some hooks and views to handle notification on entity's changes

:organization: Logilab

:copyright: 2001-2009 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"

_ = unicode

from base64 import b64encode, b64decode

from itertools import repeat

from time import time

try:

    from socket import gethostname

except ImportError:

    def gethostname(): # gae

        return 'XXX'

from logilab.common.textutils import normalize_text

from logilab.common.deprecation import class_renamed

from cubicweb import RegistryException

from cubicweb.selectors import implements, yes

from cubicweb.view import EntityView, Component

from cubicweb.common.mail import format_mail

from cubicweb.server.pool import PreCommitOperation

from cubicweb.server.hookhelper import SendMailOp

from cubicweb.server.hooksmanager import Hook

class RecipientsFinder(Component):

    """this component is responsible to find recipients of a notification

    by default user's with their email set are notified if any, else the default

    email addresses specified in the configuration are used

    """

    id = 'recipients_finder'

    __select__ = yes()

    user_rql = ('Any X,E,A WHERE X is CWUser, X in_state S, S name "activated",'

                'X primary_email E, E address A')

    def recipients(self):

        mode = self.config['default-recipients-mode']

        if mode == 'users':

            # use unsafe execute else we may don't have the right to see users

            # to notify...

            execute = self.req.unsafe_execute

            dests = [(u.get_email(), u.property_value('ui.language'))

                     for u in execute(self.user_rql, build_descr=True, propagate=True).entities()]

        elif mode == 'default-dest-addrs':

            lang = self.vreg.property_value('ui.language')

            dests = zip(self.config['default-dest-addrs'], repeat(lang))

        else: # mode == 'none'

            dests = []

        return dests

# hooks #######################################################################

class RenderAndSendNotificationView(PreCommitOperation):

    """delay rendering of notification view until precommit"""

    def precommit_event(self):

        if self.view.rset and self.view.rset[0][0] in self.session.transaction_data.get('pendingeids', ()):

            return # entity added and deleted in the same transaction

        self.view.render_and_send(**getattr(self, 'viewargs', {}))

class StatusChangeHook(Hook):

    """notify when a workflowable entity has its state modified"""

    events = ('after_add_entity',)

    accepts = ('TrInfo',)

    def call(self, session, entity):

        if not entity.from_state: # not a transition

            return

        rset = entity.related('wf_info_for')

        try:

            view = session.vreg['views'].select('notif_status_change', session,

                                                rset=rset, row=0)

        except RegistryException:

            return

        comment = entity.printable_value('comment', format='text/plain')

        if comment:

            comment = normalize_text(comment, 80,

                                     rest=entity.comment_format=='text/rest')

        RenderAndSendNotificationView(session, view=view, viewargs={

            'comment': comment, 'previous_state': entity.previous_state.name,

            'current_state': entity.new_state.name})

class RelationChangeHook(Hook):

    events = ('before_add_relation', 'after_add_relation',

              'before_delete_relation', 'after_delete_relation')

    accepts = ('Any',)

    def call(self, session, fromeid, rtype, toeid):

        """if a notification view is defined for the event, send notification

        email defined by the view

        """

        rset = session.eid_rset(fromeid)

        vid = 'notif_%s_%s' % (self.event,  rtype)

        try:

            view = session.vreg['views'].select(vid, session, rset=rset, row=0)

        except RegistryException:

            return

        RenderAndSendNotificationView(session, view=view)

class EntityChangeHook(Hook):

    events = ('after_add_entity',

              'after_update_entity')

    accepts = ('Any',)

    def call(self, session, entity):

        """if a notification view is defined for the event, send notification

        email defined by the view

        """

        rset = entity.as_rset()

        vid = 'notif_%s' % self.event

        try:

            view = session.vreg['views'].select(vid, session, rset=rset, row=0)

        except RegistryException:

            return

        RenderAndSendNotificationView(session, view=view)

# abstract or deactivated notification views and mixin ########################

class NotificationView(EntityView):

    """abstract view implementing the email API

    all you have to do by default is :

    * set id and accepts attributes to match desired events and entity types

    * set a content attribute to define the content of the email (unless you

      override call)

    """

    # XXX refactor this class to work with len(rset) > 1

    msgid_timestamp = True

    def recipients(self):

        finder = self.vreg['components'].select('recipients_finder', self.req,

                                  rset=self.rset)

        return finder.recipients()

    def subject(self):

        subject = self.req._(self.message)

        etype = entity.dc_type()

        eid = entity.eid

        login = self.user_login()

        return self.req._('%(subject)s %(etype)s #%(eid)s (%(login)s)') % locals()

    def user_login(self):

        # req is actually a session (we are on the server side), and we have to

        # prevent nested internal session

        return self.req.actual_session().user.login

    def context(self, **kwargs):

        for key, val in kwargs.iteritems():

            if val and isinstance(val, unicode) and val.strip():

               kwargs[key] = self.req._(val)

        kwargs.update({'user': self.user_login(),

                       'eid': entity.eid,

                       'etype': entity.dc_type(),

                       'url': entity.absolute_url(),

                       'title': entity.dc_long_title(),})

        return kwargs

    def cell_call(self, row, col=0, **kwargs):

        self.w(self.req._(self.content) % self.context(**kwargs))

    def construct_message_id(self, eid):

        return construct_message_id(self.config.appid, eid, self.msgid_timestamp)

    def render_and_send(self, **kwargs):

        """generate and send an email message for this view"""

        self._kwargs = kwargs

        recipients = self.recipients()

        if not recipients:

            self.info('skipping %s notification, no recipients', self.id)

            return

        if not isinstance(recipients[0], tuple):

            from warnings import warn

            warn('recipients should now return a list of 2-uple (email, language)',

                 DeprecationWarning, stacklevel=1)

            lang = self.vreg.property_value('ui.language')

            recipients = zip(recipients, repeat(lang))

        if self.rset is not None:

            # if the view is using timestamp in message ids, no way to reference

            # previous email

            if not self.msgid_timestamp:

                refs = [self.construct_message_id(eid)

                        for eid in entity.notification_references(self)]

            else:

                refs = ()

            msgid = self.construct_message_id(entity.eid)

        else:

            refs = ()

            msgid = None

        userdata = self.req.user_data()

        origlang = self.req.lang

        for emailaddr, lang in recipients:

            self.req.set_language(lang)

            # since the same view (eg self) may be called multiple time and we

            # need a fresh stream at each iteration, reset it explicitly

            self.w = None

            # XXX call render before subject to set .row/.col attributes on the

            #     view

            content = self.render(row=0, col=0, **kwargs)

            subject = self.subject()

            msg = format_mail(userdata, [emailaddr], content, subject,

                              config=self.config, msgid=msgid, references=refs)

            self.send([emailaddr], msg)

        # restore language

        self.req.set_language(origlang)

    def send(self, recipients, msg):

        SendMailOp(self.req, recipients=recipients, msg=msg)

def construct_message_id(appid, eid, withtimestamp=True):

    if withtimestamp:

        addrpart = 'eid=%s&timestamp=%.10f' % (eid, time())

    else:

        addrpart = 'eid=%s' % eid

    # we don't want any equal sign nor trailing newlines

    leftpart = b64encode(addrpart, '.-').rstrip().rstrip('=')

    return '<%s@%s.%s>' % (leftpart, appid, gethostname())

def parse_message_id(msgid, appid):

    if msgid[0] == '<':

        msgid = msgid[1:]

    if msgid[-1] == '>':

        msgid = msgid[:-1]

    try:

        values, qualif = msgid.split('@')

        padding = len(values) % 4

        values = b64decode(str(values + '='*padding), '.-')

        values = dict(v.split('=') for v in values.split('&'))

        fromappid, host = qualif.split('.', 1)

    except:

        return None

    if appid != fromappid or host != gethostname():

        return None

    return values

class StatusChangeMixIn(object):

    id = 'notif_status_change'

    msgid_timestamp = True

    message = _('status changed')

    content = _("""

%(user)s changed status from <%(previous_state)s> to <%(current_state)s> for entity

'%(title)s'

%(comment)s

url: %(url)s

""")

###############################################################################

# Actual notification views.                                                  #

#                                                                             #

# disable them at the recipients_finder level if you don't want them          #

###############################################################################

# XXX should be based on dc_title/dc_description, no?

class ContentAddedView(NotificationView):

    __abstract__ = True

    id = 'notif_after_add_entity'

    msgid_timestamp = False

    message = _('new')

    content = """

%(title)s

%(content)s

url: %(url)s

"""

    def context(self, **kwargs):

        content = entity.printable_value(self.content_attr, format='text/plain')

        if content:

            contentformat = getattr(entity, self.content_attr + '_format', 'text/rest')

            content = normalize_text(content, 80, rest=contentformat=='text/rest')

        return super(ContentAddedView, self).context(content=content, **kwargs)

    def subject(self):

        return  u'%s #%s (%s)' % (self.req.__('New %s' % entity.e_schema),

                                  entity.eid, self.user_login())

NormalizedTextView = class_renamed('NormalizedTextView', ContentAddedView)