#!/usr/bin/env python3

# -*- coding: utf-8 -*-

from __future__ import absolute_import, division, unicode_literals

import gpg

import os

import os.path

import sys

# 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 License for 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

# <https://www.gnu.org/licenses/>.

print("""

This script exports one or more secret keys.

The gpg-agent and pinentry are invoked to authorise the export.

""")

c = gpg.Context(armor=True)

if len(sys.argv) >= 4:

    keyfile = sys.argv[1]

    logrus = sys.argv[2]

    homedir = sys.argv[3]

elif len(sys.argv) == 3:

    keyfile = sys.argv[1]

    logrus = sys.argv[2]

    homedir = input("Enter the GPG configuration directory path (optional): ")

elif len(sys.argv) == 2:

    keyfile = sys.argv[1]

    logrus = input("Enter the UID matching the secret key(s) to export: ")

    homedir = input("Enter the GPG configuration directory path (optional): ")

else:

    keyfile = input("Enter the path and filename to save the secret key to: ")

    logrus = input("Enter the UID matching the secret key(s) to export: ")

    homedir = input("Enter the GPG configuration directory path (optional): ")

if len(homedir) == 0:

    homedir = None

elif homedir.startswith("~"):

    userdir = os.path.expanduser(homedir)

    if os.path.exists(userdir) is True:

        homedir = os.path.realpath(userdir)

    else:

        homedir = None

else:

    homedir = os.path.realpath(homedir)

if homedir is not None and os.path.exists(homedir) is False:

    homedir = None

elif homedir is not None and os.path.exists(homedir) is True:

    if os.path.isdir(homedir) is False:

        homedir = None

    else:

        pass

if homedir is not None:

    c.home_dir = homedir

else:

    pass

try:

    result = c.key_export_secret(pattern=logrus)

except:

    result = c.key_export_secret(pattern=None)

if result is not None:

    with open(keyfile, "wb") as f:

        f.write(result)

    os.chmod(keyfile, 0o600)

else:

    pass