import ceod.utils as ceod_utils
import contextlib
import os
import grp
import pwd
import subprocess
from subprocess import DEVNULL
import tempfile
from unittest.mock import patch

import gssapi
import pytest


# map principals to GSSAPI credentials
_cache = {}


@contextlib.contextmanager
def gssapi_token_ctx(principal: str):
    """
    Temporarily set KRB5CCNAME to a ccache storing credentials
    for the specified user, and yield the GSSAPI credentials.
    """
    old_krb5ccname = os.environ['KRB5CCNAME']
    try:
        if principal not in _cache:
            f = tempfile.NamedTemporaryFile()
            os.environ['KRB5CCNAME'] = 'FILE:' + f.name
            args = ['kinit', principal]
            if principal == 'ceod/admin':
                args = ['kinit', '-k', principal]
            subprocess.run(
                args, stdout=DEVNULL, text=True, input='krb5', check=True)
            creds = gssapi.Credentials(name=gssapi.Name(principal), usage='initiate')
            # Keep the credential cache files around as long as the creds are
            # used, otherwise we get a "Invalid credential was supplied" error
            _cache[principal] = creds, f
        else:
            creds, f = _cache[principal]
            os.environ['KRB5CCNAME'] = 'FILE:' + f.name
        yield creds.export()
    finally:
        os.environ['KRB5CCNAME'] = old_krb5ccname


@pytest.fixture(scope='session', autouse=True)
def ccache_cleanup():
    """Make sure the ccache files get deleted at the end of the tests."""
    yield
    _cache.clear()


@contextlib.contextmanager
def gen_password_mock_ctx():
    with patch.object(ceod_utils, 'gen_password') as mock:
        mock.return_value = 'krb5'
        yield


@contextlib.contextmanager
def mocks_for_create_user_ctx():
    with gen_password_mock_ctx(), \
            patch.object(pwd, 'getpwuid') as getpwuid_mock, \
            patch.object(grp, 'getgrgid') as getgrgid_mock:
        # Normally, if getpwuid or getgrgid do *not* raise a KeyError,
        # then LDAPService will skip that UID. Therefore, by raising a
        # KeyError, we are making sure that the UID will *not* be skipped.
        getpwuid_mock.side_effect = KeyError()
        getgrgid_mock.side_effect = KeyError()
        yield