#!/usr/bin/env python3
# -*- coding: utf-8 -*-

# Copyright (C) 2019 Daniel Kahn Gillmor
#
# This program 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.
#
# This program 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 this program.  If not, see <https://www.gnu.org/licenses/>.
'''
This script reads a MIME message from stdin and produces a treelike
representation on it stdout.

Example:
0 dkg@alice:~$ printmimestructure < 'Maildir/cur/1269025522.M338697P12023.monkey,S=6459,W=6963:2,Sa'
└┬╴multipart/signed 6546 bytes
 ├─╴text/plain inline 895 bytes
 └─╴application/pgp-signature inline [signature.asc] 836 bytes
0 dkg@alice:~$

If you want to number the parts, i suggest piping the output through
something like "cat -n"
'''
import email
import sys

def print_part(z, prefix):
    fname = '' if z.get_filename() is None else ' [' + z.get_filename() + ']'
    cset = '' if z.get_charset() is None else ' (' + z.get_charset() + ')'
    disp = z.get_params(None, header='Content-Disposition')
    if (disp is None):
        disposition = ''
    else:
        disposition = ''
        for d in disp:
            if d[0] in [ 'attachment', 'inline' ]:
                disposition = ' ' + d[0]
    if z.is_multipart():
        nbytes = len(z.as_string())
    else:
        nbytes = len(z.get_payload())

    print('{}{}{}{}{} {:d} bytes'.format(
        prefix,
        z.get_content_type(),
        cset,
        disposition,
        fname,
        nbytes,
    ))

def test(z, prefix=''):
    if (z.is_multipart()):
        print_part(z, prefix+'┬╴')
        if prefix.endswith('└'):
            prefix = prefix.rpartition('└')[0] + ' '
        if prefix.endswith('├'):
            prefix = prefix.rpartition('├')[0] + '│'
        parts = z.get_payload()
        i = 0
        while (i < parts.__len__()-1):
            test(parts[i], prefix + '├')
            i += 1
        test(parts[i], prefix + '└')
        # FIXME: show epilogue?
    else:
        print_part(z, prefix+'─╴')

test(email.message_from_file(sys.stdin), '└')