# copyright 2003-2014 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/>.
"""some views to handle notification on data changes"""


from cubicweb import _

from itertools import repeat

from logilab.common.textutils import normalize_text
from logilab.common.registry import yes

from cubicweb.view import Component, EntityView
from cubicweb.server.hook import SendMailOp
from cubicweb.mail import construct_message_id, format_mail
from cubicweb.server.session import Connection, InternalManager


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
    """
    __regid__ = '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._cw.vreg.config['default-recipients-mode']
        if mode == 'users':
            execute = self._cw.execute
            dests = list(execute(self.user_rql, build_descr=True).entities())
        elif mode == 'default-dest-addrs':
            lang = self._cw.vreg.property_value('ui.language')
            dests = zip(self._cw.vreg.config['default-dest-addrs'], repeat(lang))
        else:  # mode == 'none'
            dests = []
        return dests


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


class SkipEmail(Exception):
    """raise this if you decide to skip an email during its generation"""


class NotificationView(EntityView):
    """abstract view implementing the "email" API (eg to simplify sending
    notification)
    """
    # XXX refactor this class to work with len(rset) > 1

    msgid_timestamp = True

    # to be defined on concrete sub-classes
    content = None  # body of the mail
    message = None  # action verb of the subject

    # this is usually the method to call
    def render_and_send(self, **kwargs):
        """generate and send email messages for this view"""
        # render_emails changes self._cw so cache it here so all mails are sent
        # after we commit our transaction.
        cnx = self._cw
        for msg, recipients in self.render_emails(**kwargs):
            SendMailOp(cnx, recipients=recipients, msg=msg)

    def cell_call(self, row, col=0, **kwargs):
        self.w(self._cw._(self.content) % self.context(**kwargs))

    def render_emails(self, **kwargs):
        """generate and send emails for this view (one per recipient)"""
        self._kwargs = kwargs
        recipients = self.recipients()
        if not recipients:
            self.info('skipping %s notification, no recipients', self.__regid__)
            return
        if self.cw_rset is not None:
            entity = self.cw_rset.get_entity(self.cw_row or 0, self.cw_col or 0)
            # 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.cw_adapt_to('INotifiable').notification_references(self)]
            else:
                refs = ()
            msgid = self.construct_message_id(entity.eid)
        else:
            refs = ()
            msgid = None
        req = self._cw
        self.user_data = req.user_data()
        for something in recipients:
            if isinstance(something, tuple):
                emailaddr, lang = something
                user = InternalManager(lang=lang)
            else:
                emailaddr = something.cw_adapt_to('IEmailable').get_email()
                user = something
            # hi-jack self._cw to get a session for the returned user
            with Connection(self._cw.repo, user) as cnx:
                self._cw = cnx
                try:
                    # 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
                    try:
                        # XXX forcing the row & col here may make the content and
                        #     subject inconsistent because subject will depend on
                        #     self.cw_row & self.cw_col if they are set.
                        content = self.render(row=0, col=0, **kwargs)
                        subject = self.subject()
                    except SkipEmail:
                        continue
                    except Exception as ex:
                        # shouldn't make the whole transaction fail because of rendering
                        # error (unauthorized or such) XXX check it doesn't actually
                        # occurs due to rollback on such error
                        self.exception(str(ex))
                        continue
                    msg = format_mail(self.user_data, [emailaddr], content, subject,
                                      config=self._cw.vreg.config, msgid=msgid, references=refs)
                    yield msg, [emailaddr]
                finally:
                    self._cw = req

    # recipients handling ######################################################

    def recipients(self):
        """return a list of either 2-uple (email, language) or user entity to
        whom this email should be sent
        """
        finder = self._cw.vreg['components'].select(
            'recipients_finder', self._cw, rset=self.cw_rset,
            row=self.cw_row or 0, col=self.cw_col or 0)
        return finder.recipients()

    # email generation helpers #################################################

    def construct_message_id(self, eid):
        return construct_message_id(self._cw.vreg.config.appid, eid,
                                    self.msgid_timestamp)

    def format_field(self, attr, value):
        return ':%(attr)s: %(value)s' % {'attr': attr, 'value': value}

    def format_section(self, attr, value):
        return '%(attr)s\n%(ul)s\n%(value)s\n' % {
            'attr': attr, 'ul': '-' * len(attr), 'value': value}

    def subject(self):
        entity = self.cw_rset.get_entity(self.cw_row or 0, self.cw_col or 0)
        subject = self._cw._(self.message)
        etype = entity.dc_type()
        eid = entity.eid
        login = self.user_data['login']
        return self._cw._('%(subject)s %(etype)s #%(eid)s (%(login)s)') % locals()

    def context(self, **kwargs):
        entity = self.cw_rset.get_entity(self.cw_row or 0, self.cw_col or 0)
        for key, val in kwargs.items():
            if val and isinstance(val, str) and val.strip():
                kwargs[key] = self._cw._(val)
        kwargs.update({'user': self.user_data['login'],
                       'eid': entity.eid,
                       'etype': entity.dc_type(),
                       'url': entity.absolute_url(),
                       'title': entity.dc_long_title()})
        return kwargs


class StatusChangeMixIn(object):
    __regid__ = '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 class for notification on entity/relation

    all you have to do by default is :
    * set id and __select__ attributes to match desired events and entity types
    * set a content attribute to define the content of the email (unless you
      override call)
    """
    __abstract__ = True
    __regid__ = 'notif_after_add_entity'
    msgid_timestamp = False
    message = _('new')
    content = """
%(title)s

%(content)s

url: %(url)s
"""
    # to be defined on concrete sub-classes
    content_attr = None

    def context(self, **kwargs):
        entity = self.cw_rset.get_entity(self.cw_row or 0, self.cw_col or 0)
        content = entity.printable_value(self.content_attr, format='text/plain')
        if content:
            contentformat = getattr(entity, self.content_attr + '_format',
                                    'text/rest')
            # XXX don't try to wrap rest until we've a proper transformation (see
            # #103822)
            if contentformat != 'text/rest':
                content = normalize_text(content, 80)
        return super(ContentAddedView, self).context(content=content, **kwargs)

    def subject(self):
        entity = self.cw_rset.get_entity(self.cw_row or 0, self.cw_col or 0)
        return u'%s #%s (%s)' % (self._cw.__('New %s' % entity.e_schema),
                                 entity.eid, self.user_data['login'])


def format_value(value):
    if isinstance(value, str):
        return u'"%s"' % value
    return value


class EntityUpdatedNotificationView(NotificationView):
    """abstract class for notification on entity/relation

    all you have to do by default is :
    * set id and __select__ attributes to match desired events and entity types
    * set a content attribute to define the content of the email (unless you
      override call)
    """
    __abstract__ = True
    __regid__ = 'notif_entity_updated'
    msgid_timestamp = True
    message = _('updated')
    no_detailed_change_attrs = ()
    content = """
Properties have been updated by %(user)s:

%(changes)s

url: %(url)s
"""

    def context(self, changes=(), **kwargs):
        context = super(EntityUpdatedNotificationView, self).context(**kwargs)
        _ = self._cw._
        formatted_changes = []
        entity = self.cw_rset.get_entity(self.cw_row or 0, self.cw_col or 0)
        for attr, oldvalue, newvalue in sorted(changes):
            # check current user has permission to see the attribute
            rschema = self._cw.vreg.schema[attr]
            if rschema.final:
                rdef = entity.e_schema.rdef(rschema)
                if not rdef.has_perm(self._cw, 'read', eid=self.cw_rset[0][0]):
                    continue
            # XXX suppose it's a subject relation...
            elif not rschema.has_perm(self._cw, 'read',
                                      fromeid=self.cw_rset[0][0]):
                continue
            if attr in self.no_detailed_change_attrs:
                msg = _('%s updated') % _(attr)
            elif oldvalue not in (None, ''):
                msg = _('%(attr)s updated from %(oldvalue)s to %(newvalue)s') % {
                    'attr': _(attr),
                    'oldvalue': format_value(oldvalue),
                    'newvalue': format_value(newvalue)}
            else:
                msg = _('%(attr)s set to %(newvalue)s') % {
                    'attr': _(attr), 'newvalue': format_value(newvalue)}
            formatted_changes.append('* ' + msg)
        if not formatted_changes:
            # current user isn't allowed to see changes, skip this notification
            raise SkipEmail()
        context['changes'] = '\n'.join(formatted_changes)
        return context

    def subject(self):
        entity = self.cw_rset.get_entity(self.cw_row or 0, self.cw_col or 0)
        return u'%s #%s (%s)' % (self._cw.__('Updated %s' % entity.e_schema),
                                 entity.eid, self.user_data['login'])