"""Common utilies to format / semd emails.

"""

__docformat__ = "restructuredtext en"

from base64 import b64encode, b64decode

from time import time

from email.MIMEMultipart import MIMEMultipart

from email.MIMEText import MIMEText

from email.MIMEImage import MIMEImage

from email.Header import Header

try:

    from socket import gethostname

except ImportError:

    def gethostname(): # gae

        return 'XXX'

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:

        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

    subject = subject.splitlines()[0]

    msg['Subject'] = header(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

    # 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.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.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, 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"""