#!/usr/bin/python3
# -*- coding: utf-8 -*-
#
# script to manipulate password file
#
#    Copyright (C) 2017  AleaJactaEst
#
#    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 <http://www.gnu.org/licenses/>.


import bcrypt
import argparse
import sys
import os
import getpass

__VERSION__ = '1.0'


class PasswordFile:
    def __init__(self, passwordfile, createfile, password_comand_line, username, password):
        self.passwordfile = passwordfile
        self.users = {}

        if not password_comand_line:
            if password is not None:
                raise Exception("password in command line (but option disable to read this password).")
            else:
                self.password = None
        elif password is None:
            raise Exception("Missing password.")
        else:
            self.password = password
        self.username = username

        if not os.path.exists(self.passwordfile):
            if createfile:
                with open(self.passwordfile, 'wt', encoding='utf-8') as fp:
                    fp.write('\n')
            else:
                raise Exception("%s does not exist." % self.passwordfile)
        else:
            self.__load__()

    def __load__(self):
        with open(self.passwordfile, 'rt') as fp:
            for line in fp:
                line = line.strip()
                if not line:
                    continue
                username, password = line.split(':', maxsplit=1)
                self.users.setdefault(username, password)

    def save(self):
        with open(self.passwordfile, 'wt', encoding='utf-8') as fp:
            for user in sorted(self.users):
                fp.write('%s:%s\n' % (user,  self.users[user]))

    def update(self):
        if self.password is None:
            self.password = getpass.getpass('New password:')
            check = getpass.getpass('Re-type new password:')
            if self.password != check:
                raise Exception("password verification error")

        hashed_password = bcrypt.hashpw(self.password.encode('utf-8'), bcrypt.gensalt()).decode('utf8')
        self.users[self.username] = hashed_password
        print("Adding password for user %s" % self.username)

    def verify(self):
        if self.password is None:
            self.password = getpass.getpass('Enter password:')
        if bcrypt.checkpw(self.password.encode('utf-8'), self.users[self.username].encode('utf-8')):
            print("Password for user %s correct." % self.username)
        else:
            raise Exception("password verification failed.")

    def delete(self):
        if self.username in self.users:
            del self.users[self.username]


def root(passwordfile, create, password_comand_line, username, password, delete, verify):
    pf = PasswordFile(passwordfile, create, password_comand_line, username, password)
    if delete:
        pf.delete()
        pf.save()
    elif verify:
        pf.verify()
    else:
        pf.update()
        pf.save()


def main(args=sys.argv[1:]):
    """ Main function

        :param list args: root password
    """
    parser = argparse.ArgumentParser(description='password manager')
    parser.add_argument('--version', action='version', version='%(prog)s ' + __VERSION__)

    parser.add_argument('-c', '--create', action='store_true',
                        help='create a new file', default=False)
    parser.add_argument('-D', '--delete', action='store_true',
                        help='delete username', default=False)
    parser.add_argument('-v', '--verify', action='store_true',
                        help='Verify password for the specified user.', default=False)
    parser.add_argument('-b', '--password-comand-line', action='store_true',
                        help='Use the password from the command line rather than prompting for it.',
                        default=False)
    parser.add_argument('passwordfile', type=str, help='file contains all password')
    parser.add_argument('username', type=str)
    parser.add_argument('password', type=str, nargs='?')
    param = parser.parse_args(args)
    root(param.passwordfile,
         param.create,
         param.password_comand_line,
         param.username,
         param.password,
         param.delete, param.verify)


if __name__ == '__main__':
    main()