#!/usr/bin/python
# add_signature -- Adds standard signatures to AUTH user email.
# Copyright (C) 2008  Enda Cronnolly <enda@codefoundry.com>
# Copyright (C) 2008  Gordon Messmer <gordon@dragonsdawn.net>
#
# This file is part of pythonfilter.
#
# pythonfilter is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# pythonfilter 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 General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with pythonfilter.  If not, see <http://www.gnu.org/licenses/>.

import sys
import email
try:
    import email.charset
    import email.generator
    import email.mime.multipart
    import email.mime.text
except ImportError:
    import email.Charset
    import email.Generator
    import email.MIMEMultipart
    import email.MIMENonMultipart
    import email.MIMEText
    email.charset = email.Charset
    email.generator = email.Generator
    class dummy: pass
    email.mime = dummy()
    email.mime.multipart = email.MIMEMultipart
    email.mime.text = email.MIMEText
from cStringIO import StringIO
import courier.control
import courier.xfilter


domains = {'example.com': '/etc/courier/signatures/example.com'}


def getSignatureForDomain(domain):
    if domain in domains:
        sigFile = open(domains[domain])
        return sigFile.read()
    else:
        return None


def initFilter():
    courier.config.applyModuleConfig('add_signature.py', globals())
    # Record in the system log that this filter was initialized.
    sys.stderr.write('Initialized the "add_signature" python filter\n')


def doFilter(bodyFile, controlFileList):
    sender = courier.control.getAuthUser(controlFileList, bodyFile)
    if not sender:
        return ''
    senderBits = sender.split('@')
    if len(senderBits) == 1:
        signature = getSignatureForDomain('')
    else:
        signature = getSignatureForDomain(senderBits[1])
    if not signature:
        return ''
    # Set the preferred encoding for UTF-8, which will be used in the signature
    email.charset.add_charset( 'utf-8', email.charset.SHORTEST, email.charset.QP, None )
    # Load the message from the bodyFile
    try:
        mfilter = courier.xfilter.XFilter('add_signature',
                                          bodyFile, controlFileList)
    except courier.xfilter.LoopError, e:
        # LoopError indicates that we've already filtered this message.
        return ''
    original = mfilter.getMessage()
    # Create a new message object
    msg = email.mime.multipart.MIMEMultipart('mixed')
    # Attach the original message and the signature.
    msg.attach(original)
    msg.attach(email.mime.text.MIMEText(signature, _charset='utf-8'))
    # Move the headers from the original message to the new message.
    for x in original.items():
        # Dont' move the following MIME related headers.
        if x[0] in ('Content-Type', 'Content-Transfer-Encoding',
                    'Content-Disposition', 'Content-Description',
                    'MIME-Version'):
            continue
        msg.add_header(x[0], x[1])
        del(original[x[0]])
    # Replace the message body
    mfilter.setMessage(msg)
    submitVal = mfilter.submit()
    # Return the value from submit(), which may stop other filters
    # from running.
    return submitVal