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

from __future__ import absolute_import, division, unicode_literals

# Copyright (C) 2018 Ben McGinnes <ben@gnupg.org>
#
# 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 2 of the License, or (at your option) any later
# version.
#
# This program is free software; you can redistribute it and/or modify it under
# the terms of the GNU Lesser General Public License as published by the Free
# Software Foundation; either version 2.1 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 and the GNU
# Lesser General Public Licensefor more details.
#
# You should have received a copy of the GNU General Public License and the GNU
# Lesser General Public along with this program; if not, see
# <http://www.gnu.org/licenses/>.

import gpg
import os
import os.path
import sys

c = gpg.Context(armor=True)
k = gpg.Data()

print("""
This script exports one or more secret keys to a file.

Will prompt for passphrase using gpg-agent and pinentry for each key to be
exported.

If the user or key ID(s) are not entered then it will attempt to export all
available keys and will prompt for the passphrase of each one.
""")

if len(sys.argv) > 3:
    filepth = sys.argv[1]
    homedir = sys.argv[2]
    keytext = sys.argv[3]
elif len(sys.argv) == 3:
    filepth = sys.argv[1]
    homedir = sys.argv[2]
    keytext = input("Enter the user or key ID for export: ")
elif len(sys.argv) == 2:
    filepth = sys.argv[1]
    homedir = input("Enter the GPG configuration directory path (optional): ")
    keytext = input("Enter the user or key ID for export: ")
else:
    filepth = input("Enter the filename and path of the key file: ")
    homedir = input("Enter the GPG configuration directory path (optional): ")
    keytext = input("Enter the user or key ID for export (optional): ")

if homedir.startswith("~"):
    if os.path.exists(os.path.expanduser(homedir)) is True:
        c.home_dir = os.path.expanduser(homedir)
    else:
        pass
elif os.path.exists(homedir) is True:
    c.home_dir = homedir
else:
    pass

c.op_export(keytext, gpg.core.gpgme.GPGME_EXPORT_MODE_SECRET, k)
k.seek(0, os.SEEK_SET)
seckey = k.read()

with open(filepth, "wb") as f:
    f.write(seckey)

os.chmod(filepth, 0o600)