# -*- python -*-
# -*- coding: utf-8 -*-
#
# Debian Member Portfolio Service application key ring analyzer tool
#
# Copyright © 2009-2023 Jan Dittberner <jan@dittberner.info>
#
# This file is part of the Debian Member Portfolio Service.
#
# Debian Member Portfolio Service is free software: you can redistribute it
# and/or modify it under the terms of the GNU Affero General Public License as
# published by the Free Software Foundation, either version 3 of the License,
# or (at your option) any later version.
#
# Debian Member Portfolio Service 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 Affero
# General Public License for more details.
#
# You should have received a copy of the GNU Affero General Public License
# along with this program.  If not, see <https://www.gnu.org/licenses/>.
#
"""
This is a tool that analyzes GPG and PGP key rings and stores the
retrieved data in a file database. The tool was inspired by Debian
qa's carnivore.
"""

import configparser
import dbm
import email.utils
import glob
import logging
import os
import os.path
import subprocess
import sys
from importlib import resources

CONFIG = configparser.ConfigParser()


def _get_keyrings():
    """
    Gets the available keyring files from the keyring directory
    configured in portfolio.ini.
    """
    keyring_dir = os.path.expanduser(CONFIG.get("DEFAULT", "keyring.dir"))
    logging.debug("keyring dir is %s", keyring_dir)
    keyrings = glob.glob(os.path.join(keyring_dir, "*.gpg"))
    keyrings.extend(glob.glob(os.path.join(keyring_dir, "*.pgp")))
    keyrings.sort()
    return keyrings


def _parse_uid(uid):
    """
    Parse an uid of the form 'Real Name <email@example.com>' into email
    and real name parts.
    """

    # First try with the Python library, but it doesn't always catch everything
    (name, mail) = email.utils.parseaddr(uid)
    if (not name) and (not mail):
        logging.warning("malformed uid %s", uid)
    if (not name) or (not mail):
        logging.debug("strange uid %s: '%s' - <%s>", uid, name, mail)
        # Try and do better than the python library
        if "@" not in mail:
            uid = uid.strip()
            # First, strip comment
            s = uid.find("(")
            e = uid.find(")")
            if s >= 0 and e >= 0:
                uid = uid[:s] + uid[e + 1 :]
            s = uid.find("<")
            e = uid.find(">")
            mail = None
            if s >= 0 and e >= 0:
                mail = uid[s + 1 : e]
                uid = uid[:s] + uid[e + 1 :]
            uid = uid.strip()
            if not mail and uid.find("@") >= 0:
                mail, uid = uid, mail

            name = uid
            logging.debug("corrected: '%s' - <%s>", name, mail)
    return name, mail


result_dict = {}


def _get_canonical(key):
    if key not in result_dict:
        result_dict[key] = []
    return key


def _add_to_result(key, new_value):
    logging.debug("adding %s: %s", key, new_value)
    the_key = _get_canonical(key)
    if new_value not in result_dict[the_key]:
        result_dict[the_key].append(new_value)


def _handle_mail(mail, fpr):
    if mail.endswith("@debian.org"):
        login = mail[0 : -len("@debian.org")]
        _add_to_result("login:email:%s" % mail, login)
        _add_to_result("login:fpr:%s" % fpr, login)
        _add_to_result("fpr:login:%s" % login, fpr)
    _add_to_result("fpr:email:%s" % mail, fpr)
    _add_to_result("email:fpr:%s" % fpr, mail)


def _handle_uid(uid, fpr):
    mail = None
    # Do stuff with 'uid'
    if uid:
        (uid, mail) = _parse_uid(uid)
        if mail:
            _handle_mail(mail, fpr)
    if uid:
        _add_to_result("name:fpr:%s" % fpr, uid)
        if mail:
            _add_to_result("name:email:%s" % mail, uid)
    return fpr


def process_gpg_list_keys_line(line, fpr):
    """
    Process a line of gpg --list-keys --with-colon output.
    """
    items = line.split(":")
    if items[0] == "pub":
        return None
    if items[0] == "fpr":
        return items[9].strip()
    if items[0] == "uid":
        if items[1] == "r":
            return fpr
        return _handle_uid(items[9].strip(), fpr)
    else:
        return fpr


def process_keyrings():
    """Process the keyrings and store the extracted data in an anydbm file."""
    for keyring in _get_keyrings():
        logging.debug("get data from %s", keyring)
        proc = subprocess.Popen(
            [
                "gpg",
                "--no-options",
                "--no-default-keyring",
                "--homedir",
                os.path.expanduser(CONFIG.get("DEFAULT", "gnupghome")),
                "--no-expensive-trust-checks",
                "--keyring",
                keyring,
                "--list-keys",
                "--with-colons",
                "--fixed-list-mode",
                "--with-fingerprint",
                "--with-fingerprint",
            ],
            stdout=subprocess.PIPE,
        )
        fpr = None
        for line in proc.stdout.readlines():
            try:
                line = line.decode("utf8")
            except UnicodeDecodeError:
                line = line.decode("iso8859-1")
            fpr = process_gpg_list_keys_line(line, fpr)
        ret_code = proc.wait()
        if ret_code != 0:
            logging.error("subprocess ended with return code %d", ret_code)
    dbm_filename = str(
        resources.files("debianmemberportfolio.model").joinpath("keyringcache")
    )
    db = dbm.open(dbm_filename, "c")
    for key in result_dict:
        db[key] = ":".join(result_dict[key])
    db.close()


if __name__ == "__main__":
    logging.basicConfig(stream=sys.stderr, level=logging.WARNING)
    CONFIG.read_string(
        resources.files("debianmemberportfolio.model")
        .joinpath("portfolio.ini")
        .read_text("utf8")
    )
    gpg_home = os.path.expanduser(CONFIG.get("DEFAULT", "gnupghome"))
    if not os.path.isdir(gpg_home):
        os.makedirs(gpg_home, 0o700)
    process_keyrings()