# Copyright (C) 2019 Philipp Hörist <philipp AT hoerist.com>
#
# This file is part of the OpenPGP Gajim Plugin.
#
# OpenPGP Gajim Plugin 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; version 3 only.
#
# OpenPGP Gajim Plugin 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 OpenPGP Gajim Plugin. If not, see <http://www.gnu.org/licenses/>.

import logging
from collections.abc import Sequence
from pathlib import Path

import gnupg
from nbxmpp.protocol import JID

from openpgp.backend.base import BaseKeyringItem
from openpgp.backend.base import BasePGPBackend
from openpgp.backend.util import parse_uid
from openpgp.modules.key_store import KeyData
from openpgp.modules.util import DecryptionFailed

log = logging.getLogger("gajim.p.openpgp.pygnupg")
if log.getEffectiveLevel() == logging.DEBUG:
    log = logging.getLogger("gnupg")
    log.addHandler(logging.StreamHandler())
    log.setLevel(logging.DEBUG)


class KeyringItem(BaseKeyringItem):

    @property
    def keyid(self) -> str:
        return self._key["keyid"]

    def _get_uid(self) -> str | None:
        for uid in self._key["uids"]:
            try:
                return parse_uid(uid)
            except Exception:
                pass

    @property
    def fingerprint(self) -> str:
        return self._key["fingerprint"]


class PythonGnuPG(BasePGPBackend):
    def __init__(self, jid: str, gnupghome: Path) -> None:
        self._gnupg = gnupg.GPG(gpgbinary="gpg", gnupghome=str(gnupghome))
        self._jid = jid
        self._own_fingerprint = None

    @staticmethod
    def _get_key_params(jid: str) -> str:
        """
        Generate --gen-key input
        """

        params = {
            "Key-Type": "RSA",
            "Key-Length": 2048,
            "Name-Real": "xmpp:%s" % jid,
        }

        out = "Key-Type: %s\n" % params.pop("Key-Type")
        for key, val in list(params.items()):
            out += "%s: %s\n" % (key, val)
        out += "%no-protection\n"
        out += "%commit\n"
        return out

    def generate_key(self) -> None:
        self._gnupg.gen_key(self._get_key_params(self._jid))

    def encrypt(
        self, payload: bytes, keys: list[KeyData]
    ) -> tuple[bytes | None, str | None]:
        recipients = [key.fingerprint for key in keys]
        log.info("encrypt to:")
        for fingerprint in recipients:
            log.info(fingerprint)

        result = self._gnupg.encrypt(
            payload,
            recipients,
            armor=False,
            sign=self._own_fingerprint,
            always_trust=True,
        )

        if result.ok:
            error = ""
        else:
            error = result.status

        return result.data, error

    def decrypt(self, payload: bytes) -> tuple[str, str]:
        result = self._gnupg.decrypt(payload, always_trust=True)
        if not result.ok:
            raise DecryptionFailed(result.status)

        assert result.fingerprint is not None
        return result.data.decode("utf8"), result.fingerprint

    def _get_key(self, fingerprint: str) -> gnupg.ListKeys:
        return self._gnupg.list_keys(keys=[fingerprint])

    def get_keys(self) -> Sequence[KeyringItem]:
        result = self._gnupg.list_keys(secret=False)
        keys: list[KeyringItem] = []
        for key in result:
            item = KeyringItem(key)
            if not item.is_xmpp_key:
                log.warning("Invalid key found, deleting key")
                log.warning(key)
                self.delete_key(item.fingerprint)
                continue
            keys.append(item)
        return keys

    def import_key(self, data: bytes, jid: JID) -> KeyringItem | None:
        log.info("Import key from %s", jid)
        result = self._gnupg.import_keys(data)
        if not result:
            log.error("Could not import key")
            log.error(result)
            return

        fpr = result.results[0]["fingerprint"]
        assert fpr is not None

        key = self._get_key(fpr)
        item = KeyringItem(key[0])
        if not item.is_valid(jid):
            log.warning("Invalid key found, deleting key")
            log.warning(key)
            self.delete_key(item.fingerprint)
            return

        return item

    def get_own_key_details(self) -> tuple[str | None, int | None]:
        result = self._gnupg.list_keys(secret=True)
        if not result:
            return None, None

        if len(result) > 1:
            log.error("More than one secret key found")
            return None, None

        self._own_fingerprint = result[0]["fingerprint"]
        return self._own_fingerprint, int(result[0]["date"])

    def export_key(self, fingerprint: str) -> bytes | None:
        key = self._gnupg.export_keys(
            fingerprint, secret=False, armor=False, minimal=True
        )
        assert isinstance(key, bytes | None)
        return key

    def delete_key(self, fingerprint: str) -> None:
        log.info("Delete Key: %s", fingerprint)
        self._gnupg.delete_keys(fingerprint)