#! /usr/bin/env python

"""Mimification and unmimification of mail messages.

Decode quoted-printable parts of a mail message or encode using

quoted-printable.

Usage:

        mimify(input, output)

        unmimify(input, output, decode_base64 = 0)

to encode and decode respectively.  Input and output may be the name

of a file or an open file object.  Only a readline() method is used

on the input file, only a write() method is used on the output file.

When using file names, the input and output file names may be the

same.

Interactive usage:

        mimify.py -e [infile [outfile]]

        mimify.py -d [infile [outfile]]

to encode and decode respectively.  Infile defaults to standard

input and outfile to standard output.

"""

# Configure

MAXLEN = 200    # if lines longer than this, encode as quoted-printable

CHARSET = 'ISO-8859-1'  # default charset for non-US-ASCII mail

QUOTE = '> '            # string replies are quoted with

# End configure

import re

__all__ = ["mimify","unmimify","mime_encode_header","mime_decode_header"]

qp = re.compile('^content-transfer-encoding:\\s*quoted-printable', re.I)

base64_re = re.compile('^content-transfer-encoding:\\s*base64', re.I)

mp = re.compile('^content-type:.*multipart/.*boundary="?([^;"\n]*)', re.I|re.S)

chrset = re.compile('^(content-type:.*charset=")(us-ascii|iso-8859-[0-9]+)(".*)', re.I|re.S)

he = re.compile('^-*\n')

mime_code = re.compile('=([0-9a-f][0-9a-f])', re.I)

mime_head = re.compile('=\\?iso-8859-1\\?q\\?([^? \t\n]+)\\?=', re.I)

repl = re.compile('^subject:\\s+re: ', re.I)

class File:

    """A simple fake file object that knows about limited read-ahead and

    boundaries.  The only supported method is readline()."""

    def __init__(self, file, boundary):

        self.file = file

        self.boundary = boundary

        self.peek = None

    def readline(self):

        if self.peek is not None:

            return ''

        line = self.file.readline()

        if not line:

            return line

        if self.boundary:

            if line == self.boundary + '\n':

                self.peek = line

                return ''

            if line == self.boundary + '--\n':

                self.peek = line

                return ''

        return line

class HeaderFile:

    def __init__(self, file):

        self.file = file

        self.peek = None

    def readline(self):

        if self.peek is not None:

            line = self.peek

            self.peek = None

        else:

            line = self.file.readline()

        if not line:

            return line

        if he.match(line):

            return line

        while 1:

            self.peek = self.file.readline()

            if len(self.peek) == 0 or \

               (self.peek[0] != ' ' and self.peek[0] != '\t'):

                return line

            line = line + self.peek

            self.peek = None

def mime_decode(line):

    """Decode a single line of quoted-printable text to 8bit."""

    newline = ''

    pos = 0

    while 1:

        res = mime_code.search(line, pos)

        if res is None:

            break

        newline = newline + line[pos:res.start(0)] + \

                  chr(int(res.group(1), 16))

        pos = res.end(0)

    return newline + line[pos:]

def mime_decode_header(line):

    """Decode a header line to 8bit."""

    newline = ''

    pos = 0

    while 1:

        res = mime_head.search(line, pos)

        if res is None:

            break

        match = res.group(1)

        # convert underscores to spaces (before =XX conversion!)

        match = ' '.join(match.split('_'))

        newline = newline + line[pos:res.start(0)] + mime_decode(match)

        pos = res.end(0)

    return newline + line[pos:]

def unmimify_part(ifile, ofile, decode_base64 = 0):

    """Convert a quoted-printable part of a MIME mail message to 8bit."""

    multipart = None

    quoted_printable = 0

    is_base64 = 0

    is_repl = 0

    if ifile.boundary and ifile.boundary[:2] == QUOTE:

        prefix = QUOTE

    else:

        prefix = ''

    # read header

    hfile = HeaderFile(ifile)

    while 1:

        line = hfile.readline()

        if not line:

            return

        if prefix and line[:len(prefix)] == prefix:

            line = line[len(prefix):]

            pref = prefix

        else:

            pref = ''

        line = mime_decode_header(line)

        if qp.match(line):

            quoted_printable = 1

            continue        # skip this header

        if decode_base64 and base64_re.match(line):

            is_base64 = 1

            continue

        ofile.write(pref + line)

        if not prefix and repl.match(line):

            # we're dealing with a reply message

            is_repl = 1

        mp_res = mp.match(line)

        if mp_res:

            multipart = '--' + mp_res.group(1)

        if he.match(line):

            break

    if is_repl and (quoted_printable or multipart):

        is_repl = 0

    # read body

    while 1:

        line = ifile.readline()

        if not line:

            return

        line = re.sub(mime_head, '\\1', line)

        if prefix and line[:len(prefix)] == prefix:

            line = line[len(prefix):]

            pref = prefix

        else:

            pref = ''

##              if is_repl and len(line) >= 4 and line[:4] == QUOTE+'--' and line[-3:] != '--\n':

##                      multipart = line[:-1]

        while multipart:

            if line == multipart + '--\n':

                ofile.write(pref + line)

                multipart = None

                line = None

                break

            if line == multipart + '\n':

                ofile.write(pref + line)

                nifile = File(ifile, multipart)

                unmimify_part(nifile, ofile, decode_base64)

                line = nifile.peek

                if not line:

                    # premature end of file

                    break

                continue

            # not a boundary between parts

            break

        if line and quoted_printable:

            while line[-2:] == '=\n':

                line = line[:-2]

                newline = ifile.readline()

                if newline[:len(QUOTE)] == QUOTE:

                    newline = newline[len(QUOTE):]

                line = line + newline

            line = mime_decode(line)

        if line and is_base64 and not pref:

            import base64

            line = base64.decodestring(line)

        if line:

            ofile.write(pref + line)

def unmimify(infile, outfile, decode_base64 = 0):

    """Convert quoted-printable parts of a MIME mail message to 8bit."""

    if type(infile) == type(''):

        ifile = open(infile)

        if type(outfile) == type('') and infile == outfile:

            import os

            d, f = os.path.split(infile)

            os.rename(infile, os.path.join(d, ',' + f))

    else:

        ifile = infile

    if type(outfile) == type(''):

        ofile = open(outfile, 'w')

    else:

        ofile = outfile

    nifile = File(ifile, None)

    unmimify_part(nifile, ofile, decode_base64)

    ofile.flush()

mime_char = re.compile('[=\177-\377]') # quote these chars in body

mime_header_char = re.compile('[=?\177-\377]') # quote these in header

def mime_encode(line, header):

    """Code a single line as quoted-printable.

    If header is set, quote some extra characters."""

    if header:

        reg = mime_header_char

    else:

        reg = mime_char

    newline = ''

    pos = 0

    if len(line) >= 5 and line[:5] == 'From ':

        # quote 'From ' at the start of a line for stupid mailers

        newline = ('=%02x' % ord('F')).upper()

        pos = 1

    while 1:

        res = reg.search(line, pos)

        if res is None:

            break

        newline = newline + line[pos:res.start(0)] + \

                  ('=%02x' % ord(res.group(0))).upper()

        pos = res.end(0)

    line = newline + line[pos:]

    newline = ''

    while len(line) >= 75:

        i = 73

        while line[i] == '=' or line[i-1] == '=':

            i = i - 1

        i = i + 1

        newline = newline + line[:i] + '=\n'

        line = line[i:]

    return newline + line

mime_header = re.compile('([ \t(]|^)([-a-zA-Z0-9_+]*[\177-\377][-a-zA-Z0-9_+\177-\377]*)(?=[ \t)]|\n)')

def mime_encode_header(line):

    """Code a single header line as quoted-printable."""

    newline = ''

    pos = 0

    while 1:

        res = mime_header.search(line, pos)

        if res is None:

            break

        newline = '%s%s%s=?%s?Q?%s?=' % \

                  (newline, line[pos:res.start(0)], res.group(1),

                   CHARSET, mime_encode(res.group(2), 1))

        pos = res.end(0)

    return newline + line[pos:]

mv = re.compile('^mime-version:', re.I)

cte = re.compile('^content-transfer-encoding:', re.I)

iso_char = re.compile('[\177-\377]')

def mimify_part(ifile, ofile, is_mime):

    """Convert an 8bit part of a MIME mail message to quoted-printable."""

    has_cte = is_qp = is_base64 = 0

    multipart = None

    must_quote_body = must_quote_header = has_iso_chars = 0

    header = []

    header_end = ''

    message = []

    message_end = ''

    # read header

    hfile = HeaderFile(ifile)

    while 1:

        line = hfile.readline()

        if not line:

            break

        if not must_quote_header and iso_char.search(line):

            must_quote_header = 1

        if mv.match(line):

            is_mime = 1

        if cte.match(line):

            has_cte = 1

            if qp.match(line):

                is_qp = 1

            elif base64_re.match(line):

                is_base64 = 1

        mp_res = mp.match(line)

        if mp_res:

            multipart = '--' + mp_res.group(1)

        if he.match(line):

            header_end = line

            break

        header.append(line)

    # read body

    while 1:

        line = ifile.readline()

        if not line:

            break

        if multipart:

            if line == multipart + '--\n':

                message_end = line

                break

            if line == multipart + '\n':

                message_end = line

                break

        if is_base64:

            message.append(line)

            continue

        if is_qp:

            while line[-2:] == '=\n':

                line = line[:-2]

                newline = ifile.readline()

                if newline[:len(QUOTE)] == QUOTE:

                    newline = newline[len(QUOTE):]

                line = line + newline

            line = mime_decode(line)

        message.append(line)

        if not has_iso_chars:

            if iso_char.search(line):

                has_iso_chars = must_quote_body = 1

        if not must_quote_body:

            if len(line) > MAXLEN:

                must_quote_body = 1

    # convert and output header and body

    for line in header:

        if must_quote_header:

            line = mime_encode_header(line)

        chrset_res = chrset.match(line)

        if chrset_res:

            if has_iso_chars:

                # change us-ascii into iso-8859-1

                if chrset_res.group(2).lower() == 'us-ascii':

                    line = '%s%s%s' % (chrset_res.group(1),

                                       CHARSET,

                                       chrset_res.group(3))

            else:

                # change iso-8859-* into us-ascii

                line = '%sus-ascii%s' % chrset_res.group(1, 3)

        if has_cte and cte.match(line):

            line = 'Content-Transfer-Encoding: '

            if is_base64:

                line = line + 'base64\n'

            elif must_quote_body:

                line = line + 'quoted-printable\n'

            else:

                line = line + '7bit\n'

        ofile.write(line)

    if (must_quote_header or must_quote_body) and not is_mime:

        ofile.write('Mime-Version: 1.0\n')

        ofile.write('Content-Type: text/plain; ')

        if has_iso_chars:

            ofile.write('charset="%s"\n' % CHARSET)

        else:

            ofile.write('charset="us-ascii"\n')

    if must_quote_body and not has_cte:

        ofile.write('Content-Transfer-Encoding: quoted-printable\n')

    ofile.write(header_end)

    for line in message:

        if must_quote_body:

            line = mime_encode(line, 0)

        ofile.write(line)

    ofile.write(message_end)

    line = message_end

    while multipart:

        if line == multipart + '--\n':

            # read bit after the end of the last part

            while 1:

                line = ifile.readline()

                if not line:

                    return

                if must_quote_body:

                    line = mime_encode(line, 0)

                ofile.write(line)

        if line == multipart + '\n':

            nifile = File(ifile, multipart)

            mimify_part(nifile, ofile, 1)

            line = nifile.peek

            if not line:

                # premature end of file

                break

            ofile.write(line)

            continue

        # unexpectedly no multipart separator--copy rest of file

        while 1:

            line = ifile.readline()

            if not line:

                return

            if must_quote_body:

                line = mime_encode(line, 0)

            ofile.write(line)

def mimify(infile, outfile):

    """Convert 8bit parts of a MIME mail message to quoted-printable."""

    if type(infile) == type(''):

        ifile = open(infile)

        if type(outfile) == type('') and infile == outfile:

            import os

            d, f = os.path.split(infile)

            os.rename(infile, os.path.join(d, ',' + f))

    else:

        ifile = infile

    if type(outfile) == type(''):

        ofile = open(outfile, 'w')

    else:

        ofile = outfile

    nifile = File(ifile, None)

    mimify_part(nifile, ofile, 0)

    ofile.flush()

import sys

if __name__ == '__main__' or (len(sys.argv) > 0 and sys.argv[0] == 'mimify'):

    import getopt

    usage = 'Usage: mimify [-l len] -[ed] [infile [outfile]]'

    decode_base64 = 0

    opts, args = getopt.getopt(sys.argv[1:], 'l:edb')

    if len(args) not in (0, 1, 2):

        print usage

        sys.exit(1)

    if (('-e', '') in opts) == (('-d', '') in opts) or \

       ((('-b', '') in opts) and (('-d', '') not in opts)):

        print usage

        sys.exit(1)

    for o, a in opts:

        if o == '-e':

            encode = mimify

        elif o == '-d':

            encode = unmimify

        elif o == '-l':

            try:

                MAXLEN = int(a)

            except (ValueError, OverflowError):

                print usage

                sys.exit(1)

        elif o == '-b':

            decode_base64 = 1

    if len(args) == 0:

        encode_args = (sys.stdin, sys.stdout)

    elif len(args) == 1:

        encode_args = (args[0], sys.stdout)

    else:

        encode_args = (args[0], args[1])

    if decode_base64:

        encode_args = encode_args + (decode_base64,)

    encode(*encode_args)