# copyright 2003-2012 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/>.

"""Common utilies to format / send emails."""

__docformat__ = "restructuredtext en"

from base64 import b64encode, b64decode

from time import time

from email.mime.multipart import MIMEMultipart

from email.mime.text import MIMEText

from email.mime.image import MIMEImage

from email.header import Header

from socket import gethostname

from cubicweb.view import EntityView

from cubicweb.entity import Entity

def header(ustring):

    return Header(ustring.encode('UTF-8'), 'UTF-8')

def addrheader(uaddr, uname=None):

    # even if an email address should be ascii, encode it using utf8 since

    # automatic tests may generate non ascii email address

    addr = uaddr.encode('UTF-8')

    if uname:

        return '%s <%s>' % (header(uname).encode(), addr)

    return addr

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 Exception:

        return None

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

        return None

    return values

def format_mail(uinfo, to_addrs, content, subject="",

                cc_addrs=(), msgid=None, references=(), config=None):

    """Sends an Email to 'e_addr' with content 'content', and subject 'subject'

    to_addrs and cc_addrs are expected to be a list of email address without

    name

    """

    assert type(content) is unicode, repr(content)

    msg = MIMEText(content.encode('UTF-8'), 'plain', 'UTF-8')

    # safety: keep only the first newline

    try:

        subject = subject.splitlines()[0]

        msg['Subject'] = header(subject)

    except IndexError:

        pass # no subject

    if uinfo.get('email'):

        email = uinfo['email']

    elif config and config['sender-addr']:

        email = unicode(config['sender-addr'])

    else:

        email = u''

    if uinfo.get('name'):

        name = uinfo['name']

    elif config and config['sender-addr']:

        name = unicode(config['sender-name'])

    else:

        name = u''

    msg['From'] = addrheader(email, name)

    if config and config['sender-addr'] and config['sender-addr'] != email:

        appaddr = addrheader(config['sender-addr'], config['sender-name'])

        msg['Reply-to'] = '%s, %s' % (msg['From'], appaddr)

    elif email:

        msg['Reply-to'] = msg['From']

    if config is not None:

        msg['X-CW'] = config.appid

    unique_addrs = lambda addrs: sorted(set(addr for addr in addrs if addr is not None))

    msg['To'] = ', '.join(addrheader(addr) for addr in unique_addrs(to_addrs))

    if cc_addrs:

        msg['Cc'] = ', '.join(addrheader(addr) for addr in unique_addrs(cc_addrs))

    if msgid:

        msg['Message-id'] = msgid

    if references:

        msg['References'] = ', '.join(references)

    return msg

class HtmlEmail(MIMEMultipart):

    def __init__(self, subject, textcontent, htmlcontent,

                 sendermail=None, sendername=None, recipients=None, ccrecipients=None):

        MIMEMultipart.__init__(self, 'related')

        self['Subject'] = header(subject)

        self.preamble = 'This is a multi-part message in MIME format.'

        # Attach alternative text message

        alternative = MIMEMultipart('alternative')

        self.attach(alternative)

        msgtext = MIMEText(textcontent.encode('UTF-8'), 'plain', 'UTF-8')

        alternative.attach(msgtext)

        # Attach html message

        msghtml = MIMEText(htmlcontent.encode('UTF-8'), 'html', 'UTF-8')

        alternative.attach(msghtml)

        if sendermail or sendername:

            self['From'] = addrheader(sendermail, sendername)

        if recipients:

            self['To'] = ', '.join(addrheader(addr) for addr in recipients if addr is not None)

        if ccrecipients:

            self['Cc'] = ', '.join(addrheader(addr) for addr in ccrecipients if addr is not None)

    def attach_image(self, data, htmlId):

        image = MIMEImage(data)

        image.add_header('Content-ID', '<%s>' % htmlId)

        self.attach(image)

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 an email message for this view"""

        delayed = kwargs.pop('delay_to_commit', None)

        for recipients, msg in self.render_emails(**kwargs):

            if delayed is None:

                self.send(recipients, msg)

            elif delayed:

                self.send_on_commit(recipients, msg)

            else:

                self.send_now(recipients, 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()

        origlang = req.lang

        for something in recipients:

            if isinstance(something, Entity):

                # hi-jack self._cw to get a session for the returned user

                self._cw = self._cw.hijack_user(something)

                emailaddr = something.cw_adapt_to('IEmailable').get_email()

            else:

                emailaddr, lang = something

                self._cw.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

            try:

                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 [emailaddr], msg

        # restore language

        req.set_language(origlang)

    # recipients / email sending ###############################################

    def recipients(self):

        """return a list of either 2-uple (email, language) or user entity to

        who 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()

    def send_now(self, recipients, msg):

        self._cw.vreg.config.sendmails([(msg, recipients)])

    def send_on_commit(self, recipients, msg):

        raise NotImplementedError

    send = send_now

    # 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.iteritems():

            if val and isinstance(val, unicode) 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 SkipEmail(Exception):

    """raise this if you decide to skip an email during its generation"""