"""Permissions for Home Assistant."""

from collections.abc import Callable, Iterable
from typing import TYPE_CHECKING

import voluptuous as vol

from .const import CAT_ENTITIES
from .entities import ENTITY_POLICY_SCHEMA, compile_entities
from .merge import merge_policies
from .models import PermissionLookup
from .types import PolicyType
from .util import test_all

if TYPE_CHECKING:
    from ..models import User

POLICY_SCHEMA = vol.Schema({vol.Optional(CAT_ENTITIES): ENTITY_POLICY_SCHEMA})

__all__ = [
    "POLICY_SCHEMA",
    "AbstractPermissions",
    "OwnerPermissions",
    "PermissionLookup",
    "PolicyPermissions",
    "PolicyType",
    "filter_entity_ids_by_permission",
    "merge_policies",
]


def filter_entity_ids_by_permission(
    user: User, entity_ids: Iterable[str], key: str
) -> list[str]:
    """Filter entity IDs to those the user can access for the given policy key."""
    if user.is_admin or user.permissions.access_all_entities(key):
        return list(entity_ids)
    check_entity = user.permissions.check_entity
    return [entity_id for entity_id in entity_ids if check_entity(entity_id, key)]


class AbstractPermissions:
    """Default permissions class."""

    _cached_entity_func: Callable[[str, str], bool] | None = None

    def _entity_func(self) -> Callable[[str, str], bool]:
        """Return a function that can test entity access."""
        raise NotImplementedError

    def access_all_entities(self, key: str) -> bool:
        """Check if we have a certain access to all entities."""
        raise NotImplementedError

    def check_entity(self, entity_id: str, key: str) -> bool:
        """Check if we can access entity."""
        if (entity_func := self._cached_entity_func) is None:
            entity_func = self._cached_entity_func = self._entity_func()

        return entity_func(entity_id, key)


class PolicyPermissions(AbstractPermissions):
    """Handle permissions."""

    def __init__(self, policy: PolicyType, perm_lookup: PermissionLookup) -> None:
        """Initialize the permission class."""
        self._policy = policy
        self._perm_lookup = perm_lookup

    def access_all_entities(self, key: str) -> bool:
        """Check if we have a certain access to all entities."""
        return test_all(self._policy.get(CAT_ENTITIES), key)

    def _entity_func(self) -> Callable[[str, str], bool]:
        """Return a function that can test entity access."""
        return compile_entities(self._policy.get(CAT_ENTITIES), self._perm_lookup)

    def __eq__(self, other: object) -> bool:
        """Equals check."""
        return isinstance(other, PolicyPermissions) and other._policy == self._policy


class _OwnerPermissions(AbstractPermissions):
    """Owner permissions."""

    def access_all_entities(self, key: str) -> bool:
        """Check if we have a certain access to all entities."""
        return True

    def _entity_func(self) -> Callable[[str, str], bool]:
        """Return a function that can test entity access."""
        return lambda entity_id, key: True


OwnerPermissions = _OwnerPermissions()