# Copyright (C) 2001-2006 Python Software Foundation
# Author: Barry Warsaw
# Contact: [email protected]

"""Encodings and related functions."""

__all__ = [
'encode_7or8bit',
'encode_base64',
'encode_noop',
'encode_quopri',
]

import base64

from quopri import encodestring as _encodestring



def _qencode(s):
enc = _encodestring(s, quotetabs=True)
# Must encode spaces, which quopri.encodestring() doesn't do
return enc.replace(' ', '=20')


def _bencode(s):
# We can't quite use base64.encodestring() since it tacks on a "courtesy
# newline". Blech!
if not s:
return s
hasnewline = (s[-1] == '\n')
value = base64.encodestring(s)
if not hasnewline and value[-1] == '\n':
return value[:-1]
return value



def encode_base64(msg):
"""Encode the message's payload in Base64.

Also, add an appropriate Content-Transfer-Encoding header.
"""
orig = msg.get_payload()
encdata = _bencode(orig)
msg.set_payload(encdata)
msg['Content-Transfer-Encoding'] = 'base64'



def encode_quopri(msg):
"""Encode the message's payload in quoted-printable.

Also, add an appropriate Content-Transfer-Encoding header.
"""
orig = msg.get_payload()
encdata = _qencode(orig)
msg.set_payload(encdata)
msg['Content-Transfer-Encoding'] = 'quoted-printable'



def encode_7or8bit(msg):
"""Set the Content-Transfer-Encoding header to 7bit or 8bit."""
orig = msg.get_payload()
if orig is None:
# There's no payload. For backwards compatibility we use 7bit
msg['Content-Transfer-Encoding'] = '7bit'
return
# We play a trick to make this go fast. If encoding to ASCII succeeds, we
# know the data must be 7bit, otherwise treat it as 8bit.
try:
orig.encode('ascii')
except UnicodeError:
# iso-2022-* is non-ASCII but still 7-bit
charset = msg.get_charset()
output_cset = charset and charset.output_charset
if output_cset and output_cset.lower().startswith('iso-2202-'):
msg['Content-Transfer-Encoding'] = '7bit'
else:
msg['Content-Transfer-Encoding'] = '8bit'
else:
msg['Content-Transfer-Encoding'] = '7bit'



def encode_noop(msg):
"""Do nothing."""