Decode the filenames of attachments exported with munpack

maildir_decode.py

#!/usr/bin/env python
# -*- coding: utf-8 -*-

from email.header import decode_header, HeaderParseError
import os
import re
import itertools
from pprint import pprint

encodings = ( 'UTF-8', 'utf-8', 'koi8-r', 'KOI8-R' )
formats = ( 'B', 'Q' )
patterns = list(("=?%s?%s?" % (enc, f) for enc, f in itertools.product(encodings, formats)))
spoiled_patterns = list((s.replace('?', 'X') for s in patterns))

for root, dirs, files in os.walk('.', topdown=False):
    for filename in files:
        full_name = root + '/' + filename
        orig_name = full_name[2:]

        for pattern, spoiled_pattern in zip(patterns, spoiled_patterns):
            if (orig_name.startswith(spoiled_pattern)):
                # cutout the suffices of duplicates
                parts = re.match(r'(.*)(\.\d+)$', orig_name)
                if (parts is None):
                    f = orig_name
                    suffix = None
                else:
                    f = parts.group(1)
                    suffix = parts.group(2)
                # cutout possible extensions out of the encoded part
                while True:
                    parts = re.match(r'(.*)(\.[^\.]+)$', f)
                    if (parts is not None and 'X=' not in parts.group(2)):
                        f = parts.group(1)
                        suffix = parts.group(2) + ("" if suffix is None else suffix)
                    else:
                        break

                # munpack spoils special characters, restoring them
                f = re.sub(r'X=X?X?' + spoiled_pattern, "?=\r\n" + pattern, f)
                f = re.sub(r'^' + spoiled_pattern, pattern, f)
                f = re.sub(r'X=$', "?=", f)
                if (not f.endswith('?=')):
                    f += '?='

                try:
                    # decoding
                    h = decode_header(f)
                    if (len(h) <> 1 or h[0][1] is None or h[0][1] not in pattern.lower()):
                        print("Parsing error: %s" % f)
                        pprint(h)
                        continue
                    f = h[0][0]
                    enc = h[0][1]

                    try:
                        f = f.decode(enc)

                        # append the suffix back
                        if (suffix):
                            f += suffix

                        # clean the name from unwanted symbols
                        f = re.sub(r'[/\\\?\*]', '_', f)

                        # make sure the name would fit in a *NIX filesystem
                        if (len(f.encode('utf-8')) > 200):
                            f = u"%s…%s" % (f[:50], f[-50:])

                        try:
                            os.rename(full_name, f)
                        except OSError:
                            print("Rename error: `%s` to `%s`" % (full_name, f))
                    except UnicodeError,e:
                        print("Malformed string (%s): %s" % (e.reason, orig_name))
                        pprint(h)
                        pprint(e.object)
                except HeaderParseError:
                    print("Couldn't parse: %s" % f)

    # cleanup the emptied directories
    if (root <> "." and len(os.listdir(root)) == 0):
        os.rmdir(root)