# Copyright 2020, Microsoft Corporation
# Copyright 2020, Chris PeBenito <pebenito@ieee.org>
#
# SPDX-License-Identifier: LGPL-2.1-only
#

import typing

from .. import exception, policyrep
from ..terulequery import TERuleQuery
from .checkermodule import CheckerModule
from .descriptors import ConfigDescriptor, ConfigSetDescriptor, ConfigPermissionSetDescriptor

SOURCE_OPT: typing.Final[str] = "source"
TARGET_OPT: typing.Final[str] = "target"
CLASS_OPT: typing.Final[str] = "tclass"
PERMS_OPT: typing.Final[str] = "perms"
EXEMPT_SRC_OPT: typing.Final[str] = "exempt_source"
EXEMPT_TGT_OPT: typing.Final[str] = "exempt_target"
EXPECT_SRC_OPT: typing.Final[str] = "expect_source"
EXPECT_TGT_OPT: typing.Final[str] = "expect_target"

__all__: typing.Final[tuple[str, ...]] = ("AssertTE",)


class AssertTE(CheckerModule):

    """Checker module for asserting a type enforcement allow rule exists (or not)."""

    check_type = "assert_te"
    check_config = frozenset((SOURCE_OPT, TARGET_OPT, CLASS_OPT, PERMS_OPT, EXEMPT_SRC_OPT,
                              EXEMPT_TGT_OPT, EXPECT_SRC_OPT, EXPECT_TGT_OPT))

    source = ConfigDescriptor[policyrep.TypeOrAttr]("lookup_type_or_attr")
    target = ConfigDescriptor[policyrep.TypeOrAttr]("lookup_type_or_attr")
    tclass = ConfigSetDescriptor[policyrep.ObjClass]("lookup_class", strict=True, expand=False)
    perms = ConfigPermissionSetDescriptor()

    exempt_source = ConfigSetDescriptor[policyrep.Type]("lookup_type_or_attr",
                                                        strict=False,
                                                        expand=True)
    exempt_target = ConfigSetDescriptor[policyrep.Type]("lookup_type_or_attr",
                                                        strict=False,
                                                        expand=True)
    expect_source = ConfigSetDescriptor[policyrep.Type]("lookup_type_or_attr",
                                                        strict=True,
                                                        expand=True)
    expect_target = ConfigSetDescriptor[policyrep.Type]("lookup_type_or_attr",
                                                        strict=True,
                                                        expand=True)

    def __init__(self, policy: policyrep.SELinuxPolicy, checkname: str,
                 config: dict[str, str]) -> None:

        super().__init__(policy, checkname, config)
        self.source = config.get(SOURCE_OPT)
        self.target = config.get(TARGET_OPT)
        self.tclass = config.get(CLASS_OPT)
        self.perms = config.get(PERMS_OPT)

        self.exempt_source = config.get(EXEMPT_SRC_OPT)
        self.exempt_target = config.get(EXEMPT_TGT_OPT)
        self.expect_source = config.get(EXPECT_SRC_OPT)
        self.expect_target = config.get(EXPECT_TGT_OPT)

        if not any((self.source, self.target, self.tclass, self.perms)):
            raise exception.InvalidCheckValue(
                "At least one of source, target, tclass, or perms options must be set.")

        source_exempt_expect_overlap = self.exempt_source & self.expect_source
        if source_exempt_expect_overlap:
            self.log.info("Overlap in expect_source and exempt_source: "
                          f"{', '.join(i.name for i in source_exempt_expect_overlap)}")

        target_exempt_expect_overlap = self.exempt_target & self.expect_target
        if target_exempt_expect_overlap:
            self.log.info("Overlap in expect_target and exempt_target: "
                          f"{', '.join(i.name for i in target_exempt_expect_overlap)}")

    def run(self) -> list[policyrep.AnyTERule | str]:
        assert any((self.source, self.target, self.tclass, self.perms)), \
            "AssertTe no options set, this is a bug."

        self.log.info("Checking TE allow rule assertion.")

        query = TERuleQuery(self.policy,
                            source=self.source,
                            target=self.target,
                            tclass=self.tclass,
                            perms=self.perms,
                            ruletype=("allow",))

        unseen_sources = set(self.expect_source)
        unseen_targets = set(self.expect_target)
        failures: list[policyrep.AnyTERule | str] = []
        for rule in sorted(query.results()):
            srcs = set(rule.source.expand())
            tgts = set(rule.target.expand())

            unseen_sources -= srcs
            unseen_targets -= tgts
            if (srcs - self.expect_source - self.exempt_source) and \
                    (tgts - self.expect_target - self.exempt_target):

                self.log_fail(str(rule))
                failures.append(rule)
            else:
                self.log_ok(str(rule))

        for item in unseen_sources:
            failure = f"Expected rule with source \"{item}\" not found."
            self.log_fail(failure)
            failures.append(failure)

        for item in unseen_targets:
            failure = f"Expected rule with target \"{item}\" not found."
            self.log_fail(failure)
            failures.append(failure)

        self.log.debug(f"{failures} failure(s)")
        return failures