postmortem

#!/usr/bin/env python3
# Description {{{1
"""Postmortem

Generate an account summary that includes complete account information,
including secrets, for selected accounts. This summary should allow the
recipients to access your accounts. The summaries are intended to be given to
the recipients after you die.

Usage:
    postmortem [options] [<recipients>...]

Options:
    -s, --send    send encrypted packet to recipient
    -r, --redact  redact secrets

Choose from: {available}.  If no recipients are specified, then summaries will
be generated for all recipients.

A description of how to configure and use this program can be found at
github.com/KenKundert/postmortem.

You can unpack an encrypted output file using::

    gpg -d -o - name.tgz.gpg | tar xzf -
"""

# License {{{1
# Copyright (C) 2016-2023 Kenneth S. Kundert
#
# 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/.

# Imports {{{1
from appdirs import user_config_dir
from avendesora import PasswordGenerator, PasswordError
from docopt import docopt
from inform import (
    Error, conjoin, cull, display, fatal, full_stop, indent, join, os_error, 
    terminate, warn, is_str, is_mapping, is_collection, is_str
)
import nestedtext as nt
from shlib import Run, to_path, mkdir, cp, rm, set_prefs as shlib_set_prefs
from textwrap import dedent
from voluptuous import Schema, Invalid, Extra, Required, REMOVE_EXTRA
import arrow
import gnupg

# Settings {{{1
# constants {{{2
prog_name = 'postmortem'
config_filename = 'config.nt'
shlib_set_prefs(use_inform=True)
__version__ = '0.8.0'
__released__ = '2021-08-10'
now = arrow.now()


# avendesora_header {{{3
avendesora_header = dedent("""
    # Exported Avendesora Accounts
    # {date}
    #
    # To adopt these accounts, you should copy this file into your existing
    # Avendesora directory: ~/.config/avendesora (you can rename this file
    # but keep the extension the same).  Then add the name of this file to the
    # accounts_files list in the ~/.config/avendesora/accounts_files file.  You
    # may then find that the account names and aliases from this file conflict
    # with your current accounts, in which case you can change the names of the
    # accounts and aliases in this file.
    #
    # Exported accounts should only be used for archival purposes. Any generated
    # secrets these accounts once contained have all be converted to obscured
    # secrets. If, at some point, it becomes necessary to change a secret, the
    # secret should be converted back to a generated secret to preserve its
    # unpredictability.

    # Imports {fold}1
    from avendesora import (
        # Basics
        Account, Hidden, Question, Script, WriteFile, OTP,

        # Account Discovery
        RecognizeAll, RecognizeAny, RecognizeTitle, RecognizeURL, RecognizeCWD,
        RecognizeHost, RecognizeUser, RecognizeEnvVar, RecognizeNetwork,
        RecognizeFile
    )

    # Accounts {fold}1
""").lstrip().format(fold='{''{''{', date=now.format('D MMMM YYYY'))

# avendesora_footer {{{3
avendesora_footer = join(
    '\n# vim:',
    'filetype=python',
    'sw=4',
    'sts=4',
    'et',
    'ai',
    'ff=unix',
    'fileencoding=utf-8',
    'foldmethod=marker',
    ':'
)

# unpack_script {{{3
unpack_script = dedent('''
    #!/bin/bash

    if [ $# -le 0 ]; then
        echo 'usage:'
        echo '    unpack <archive>.gpg ...'
        exit
    fi
    echo

    while [ $# -gt 0 ]
    do
        src="$1"
        tarfile="${src%.*}"
        archive="${tarfile%.*}"
        echo "=== $src --> $archive ==="
        gpg -d -o - "$src" | tar xvzf -
        echo
        shift
    done
''').lstrip()

# readme_contents {{{3
outer_readme_contents = dedent('''
    Run unpack to decrypt and unpack your archive using::

        ./unpack <yourname>-<date>.tgz.gpg

    It will create a directory <yourname>-<date> that contains your information.
    This directory contains sensitive information, so keep it secure.
    I recommend that you just copy out the information you need, then delete it.
''').lstrip()
inner_readme_contents = dedent('''
    The accounts.gpg file contains information about those of my accounts that
    are relevant to you.  All passwords and other secrets are expanded as of the
    time this file was created.  Time-based one-time password codes are included
    but will be out-of-date and useless.

    The avendesora_accounts.gpg file contains the same information, but in
    a form that can be imported into Avendesora. To do so, follow the
    instructions at the top of the file.  Once imported, the time-based one-time
    passwords will be generated correctly by Avendesora.

    I recommend that you attempt to access the GPG files contained in this
    package to assure that you will be able to when you need them.
''').lstrip()

# defaults {{{2
# these can be overridden in the settings file: ~/.config/postmortem
my_gpg_ids = ''
sign_with = None
salutation = ''
cc = []
recipients = dict()
avendesora_value_fieldname = 'estimated_value'
avendesora_recipients_fieldname = 'postmortem_recipients'
avendesora_gpg_passphrase_account = None
avendesora_gpg_passphrase_field = None
unpack_script_name = 'unpack'
readme_name = 'README'

# utility functions {{{2
# expand_settings() {{{3
def expand_settings(value):
    # allows macro values to be defined as a top-level setting.
    # allows macro reference to be found anywhere.
    if is_str(value):
        value = value.strip()
        if value[:1] == '@':
            value = settings[normalize(value[1:])]
        return value
    if is_mapping(value):
        return {k:expand_settings(v) for k, v in value.items()}
    if is_collection(value):
        return [expand_settings(v) for v in value]
    raise NotImplementedError(value)

# functions for setting validation and transformation {{{3
def to_str(arg):
    if isinstance(arg, str):
        return arg
    raise Invalid('expected text.')

def to_ident(arg):
    arg = to_str(arg)
    if arg.isidentifier():
        return arg
    raise Invalid('expected simple identifier')

def to_int(arg):
    try:
        return int(arg)
    except ValueError:
        raise Invalid('expected integer.')

def to_list(arg):
    if isinstance(arg, str):
        return arg.split()
    if isinstance(arg, dict):
        raise Invalid('expected list.')
    return arg

def to_set(arg):
    return set(to_list(arg))

def to_paths(arg):
    return [to_path(p).expanduser() for p in to_list(arg)]

def to_email(arg):
    user, _, host = arg.partition('@')
    if '.' in host:
        return arg
    raise Invalid('expected email address.')

def to_emails(arg):
    return [to_email(e) for e in to_list(arg)]

def to_gpg_id(arg):
    try:
        return to_email(arg)      # gpg ID may be an email addres
    except Invalid:
        try:
            int(arg, base=16)     # if not an email, it must be a hex key
            assert len(arg) >= 8  # at least 8 characters long
            return arg
        except (ValueError, AssertionError):
            raise Invalid('expected GPG id.')

def to_gpg_ids(arg):
    return [to_gpg_id(i) for i in to_list(arg)]

def normalize(key, *args):
    return '_'.join(key.strip().lower().split()) if type(key) == str else key


# schema {{{2
schema = Schema(
    {
        Required('my_gpg_ids'): to_gpg_ids,
        'sign_with': to_gpg_id,
        Required('avendesora_gpg_passphrase_account'): to_str,
        'avendesora_gpg_passphrase_field': to_str,
        'name_template': to_str,
        'cc': to_list,
        'salutation': to_str,
        Required('recipients'): {
            Extra: {
                Required('categories'): to_set,
                Required('email'): to_emails,
                'gpg_id': to_gpg_id,
                'attach': to_paths,
                'networth': to_str,
                'salutation': to_str,
                'accounts': to_int,
            }
        },
    },
    extra = REMOVE_EXTRA
)
voluptuous_error_msg_mapings = {
    'extra keys not allowed': 'unknown key',
}


try:
    # Read settings {{{1
    config_filepath = to_path(user_config_dir(prog_name), config_filename)
    if config_filepath.exists():

        # load from file
        settings = nt.load(
            config_filepath, keymap=(locmap:={}), normalize_key=normalize
        )

        # expand references
        settings = expand_settings(settings)

        # check settings and transform to desired types
        settings = schema(settings)

        # convert keys to identifiers
        settings = {'_'.join(k.split()): v for k, v in settings.items()}

        # add settings to local variables
        locals().update(settings)
    else:
        warn('no configuration file found.')

    # Read command line and process options {{{1
    cmdline = docopt(__doc__.format(available=conjoin(recipients)))
    who = cmdline['<recipients>']
    if not who:
        who = recipients
    send = cmdline['--send']
    redact = cmdline['--redact']

    # Scan accounts and gather information for recipients {{{1
    pw = PasswordGenerator()
    accounts = {}
    avendesora_accounts = {}
    for account in pw.all_accounts():
        account_name = account.get_name()
        class_name = account.__name__
        description = account.get_scalar('desc', None, None)

        # summarize account values {{{2
        data = account.get_composite('_' + avendesora_value_fieldname)
        if not data:
            data = account.get_composite(avendesora_value_fieldname)

        postmortem_recipients = account.get_scalar(avendesora_recipients_fieldname, default=None)
        if data and not postmortem_recipients:
            warn('no recipients.', culprit= account.get_name())
            continue
        if not postmortem_recipients:
            continue
        postmortem_recipients = set(postmortem_recipients.split())

        # gather information for recipients {{{2
        for name, recipient in recipients.items():
            if recipient.get('categories') & postmortem_recipients:

                # create textual version of account
                # output title
                title = ' - '.join(cull([class_name, description]))
                lines = [title, len(title)*'=']

                # output avendesora names
                aliases = account.get_composite('aliases')
                names = [account_name] + (aliases if aliases else [])
                lines.append('avendesora names: ' + ', '.join(names))

                # output user fields
                for field, keys in account.get_fields():
                    if field in [avendesora_recipients_fieldname, 'desc', 'NAME']:
                        continue
                    if keys == [None]:
                        v = account.get_value(field)
                        if redact and v.is_secret:
                            lines += v.render('{n}: <redacted>').split('\n')
                        else:
                            lines += v.render('{n}: {v}').split('\n')
                    else:
                        lines.append(field + ':')
                        for k, v in account.get_values(field):
                            if redact and v.is_secret:
                                lines += v.render('{k}: <redacted>').split('\n')
                            else:
                                lines += indent(
                                    v.render(('{k}) {d}: {v}', '{k}: {v}'))
                                ).split('\n')

                # add textual version of account to accounts
                if name not in accounts:
                    accounts[name] = []
                accounts[name].append('\n'.join(lines))

                # add code version of account to avendesora_accounts
                if not redact:
                    if name not in avendesora_accounts:
                        avendesora_accounts[name] = []
                    avendesora_accounts[name].append(account.export())

    # generate encrypted files that contain accounts for each recipient {{{1
    gpg = gnupg.GPG()
    gpg.encoding = 'utf-8'
    if sign_with and avendesora_gpg_passphrase_account:
        gpg_account = pw.get_account(avendesora_gpg_passphrase_account)
        if avendesora_gpg_passphrase_field:
            gpg_passphrase = account.get_value(avendesora_gpg_passphrase_field)
        else:
            gpg_passphrase = account.get_passcode()
        gpg_passphrase = str(gpg_passphrase.value)
    else:
        gpg_passphrase = None

    for name, recipient in recipients.items():
        if who and name not in who:
            continue
        dir_path = to_path(name_template.format(name=name, now=now))
        rm(dir_path)
        mkdir(dir_path)
        idents = (
            recipient.get('gpg_id', recipient.get('email')) + my_gpg_ids
        )

        # copy in attachments
        for each in recipient.get('attach', []):
            try:
                cp(each, dir_path)
            except OSError as e:
                warn(os_error(e))

        # save readme
        if readme_name:
            readme = to_path(dir_path/readme_name)
            readme.write_text(inner_readme_contents)
            readme.chmod(0o600)

        # generate networth report
        profile = recipient.get('networth')
        if profile:
            cmd = 'networth'.split()
            if is_str(profile):
                cmd.append(profile)
            nw = Run(cmd, 'sOeW')
            file_path = dir_path / 'networth'
            file_path.write_text(nw.stdout)

        # generates accounts.gpg
        if name in accounts:
            content = accounts[name]
            num_accounts = len(content)
            expected_num = recipient.get('accounts')
            if expected_num is not None and num_accounts != expected_num:
                warn(
                    f'expected {expected_num} accounts, {num_accounts} found.',
                    culprit=name
                )

            encrypted = gpg.encrypt('\n\n\n'.join(content), idents, armor='always')
            if not encrypted.ok:
                raise Error(
                    'unable to encrypt:', encrypted.stderr, culprit=name
                )
            try:
                file_path = dir_path / 'accounts.gpg'
                file_path.write_text(str(encrypted))
                display(f'contains {num_accounts} accounts.', culprit=name)
            except OSError as e:
                raise Error(os_error(e))
        else:
            warn('no accounts found.', culprit=name)

        # generates avendesora_accounts.gpg
        if name in avendesora_accounts:
            content = (
                [avendesora_header] +
                avendesora_accounts[name] +
                [avendesora_footer]
            )
            num_accounts = len(avendesora_accounts[name])
            encrypted = gpg.encrypt('\n\n'.join(content), idents, armor='always')
            if not encrypted.ok:
                raise Error(
                    'unable to encrypt:', encrypted.stderr, culprit=name
                )
            if not redact:
                try:
                    file_path = dir_path / 'avendesora_accounts.gpg'
                    file_path.write_text(str(encrypted))
                except OSError as e:
                    raise Error(os_error(e))

        # tar up directory
        Run(['chmod', '-R', 'go-rwx', dir_path], 'soeW')
        tar_path = dir_path.with_suffix('.tgz')
        Run(['tar', 'zcf', tar_path, dir_path], 'soeW')
        tar_path.chmod(0o600)

        # sign and encrypt tarfile
        tar_contents = tar_path.read_bytes()
        encrypted = gpg.encrypt(
            tar_contents, idents, sign=sign_with, passphrase=gpg_passphrase, 
            armor='always'
        )
        if not encrypted.ok:
            raise Error(
                'unable to encrypt:', encrypted.stderr, culprit=name
            )
        encrypted_tar_path = tar_path.with_suffix('.tgz.gpg')
        encrypted_tar_path.write_text(str(encrypted))
        encrypted_tar_path.chmod(0o600)

        # remove intermediate files & dirs
        rm(dir_path, tar_path)

        # save unpack script
        if unpack_script_name:
            unpack = to_path(unpack_script_name)
            unpack.write_text(unpack_script)
            unpack.chmod(0o700)

        # save readme
        if readme_name:
            readme = to_path(readme_name)
            readme.write_text(outer_readme_contents)
            readme.chmod(0o600)

        # send packet
        if send and recipient.get('email'):
            the_salutation = recipient.get('salutation', salutation)
            msg = dedent(f'''
                {name.title()},
                    Attached is a packet of information that should be useful
                if something were to happen to me. Please keep this information 
                secure and use it responsibly. It is encrypted with your GPG 
                key.

                You can unpack this packet using:
                    gpg -d -o - {encrypted_tar_path!s} | tar xzf -

                See https://github.com/KenKundert/postmortem for information on
                how to import my accounts into your Avendesora accounts.

                {the_salutation}

            ''')
            copy_to = 2*len(cc)*['-c']
            copy_to[1::2] = cc
            cmd = [
                'mail',
                '-s', 'postmortem packet',
                '-a', str(encrypted_tar_path),
            ] + copy_to + recipient.get('email')
            Run(cmd, 'soeW', stdin=msg)

# process exceptions {{{1
except KeyboardInterrupt:
    terminate('Killed by user.')
except nt.NestedTextError as e:
    e.terminate()
except Invalid as e:
    msg = voluptuous_error_msg_mapings.get(e.msg, e.msg)
    kind = 'key' if 'key' in msg else 'value'
    loc = locmap[tuple(e.path)]
    fatal(
        f"{'.'.join(str(p) for p in e.path)}: {full_stop(msg)}",
        codicil = loc.as_line(kind)
    )
except (PasswordError, Error) as e:
    e.terminate()
except OSError as e:
    fatal(os_error(e))

# vim: set sw=4 sts=4 et: