# -*- coding: utf-8 -*-
# (c) 2009-2023 Martin Wendt and contributors; see WsgiDAV https://github.com/mar10/wsgidav
# Licensed under the MIT license: http://www.opensource.org/licenses/mit-license.php
"""
Implementation of a domain controller that allows users to authenticate against
a Pluggable Authentication Module ('PAM').

Used by HTTPAuthenticator. Only available on linux and macOS.

See https://wsgidav.readthedocs.io/en/latest/user_guide_configure.html
"""
import threading

from wsgidav import util
from wsgidav.dc.base_dc import BaseDomainController

__docformat__ = "reStructuredText"
_logger = util.get_module_logger(__name__)

try:
    import pam
except ImportError:
    _logger.error(
        "pam_dc requires the `python-pam` module. Try `pip install wsgidav[pam]`."
    )
    raise


class PAMDomainController(BaseDomainController):
    def __init__(self, wsgidav_app, config):
        super().__init__(wsgidav_app, config)

        self.lock = threading.RLock()
        self.pam = pam.pam()

        dc_conf = util.get_dict_value(config, "pam_dc", as_dict=True)

        self.pam_service = dc_conf.get("service", "login")
        self.pam_encoding = dc_conf.get("encoding", "utf-8")
        self.pam_resetcreds = dc_conf.get("resetcreds", True)

    def __str__(self):
        return f"{self.__class__.__name__}({self.pam_service!r})"

    def get_domain_realm(self, path_info, environ):
        return f"PAM({self.pam_service})"

    def require_authentication(self, realm, environ):
        return True

    def basic_auth_user(self, realm, user_name, password, environ):
        # Seems that python_pam is not threadsafe (#265)
        with self.lock:
            is_ok = self.pam.authenticate(
                user_name,
                password,
                service=self.pam_service,
                resetcreds=self.pam_resetcreds,
                encoding=self.pam_encoding,
            )
            if not is_ok:
                _logger.warning(
                    "pam.authenticate({!r}, '<redacted>', {!r}) failed with code {}: {}".format(
                        user_name, self.pam_service, self.pam.code, self.pam.reason
                    )
                )
                return False

        _logger.debug(f"User {user_name!r} logged on.")
        return True

    def supports_http_digest_auth(self):
        # We don't have access to a plaintext password (or stored hash)
        return False