#
# Copyright (c) 2021 Nitric Technologies Pty Ltd.
#
# This file is part of Nitric Python 3 SDK.
# See https://github.com/nitrictech/python-sdk for further info.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#
from __future__ import annotations

import asyncio
from abc import ABC, abstractmethod
from asyncio import Task

from typing import TypeVar, Type, Union, List

from grpclib import GRPCError
from nitricapi.nitric.resource.v1 import Action, PolicyResource, Resource, ResourceType, ResourceDeclareRequest, \
    ResourceServiceStub

from nitric.api.exception import exception_from_grpc_error
from nitric.utils import new_default_channel

T = TypeVar("T", bound="BaseResource")


class BaseResource(ABC):
    """A base resource class with common functionality."""

    cache = {}

    def __init__(self):
        """Construct a new resource."""
        self._reg: Union[Task, None] = None
        self._channel = new_default_channel()
        self._resources_stub = ResourceServiceStub(channel=self._channel)

    @abstractmethod
    async def _register(self):
        pass

    @classmethod
    def make(cls: Type[T], name: str) -> T:
        """
        Create and register the resource.

        The registration process for resources async, so this method should be used instead of __init__.
        """
        # Todo: store the resource reference in a cache to avoid duplicate registrations
        r = cls(name)
        try:
            loop = asyncio.get_running_loop()
            r._reg = loop.create_task(r._register())
        except RuntimeError:
            loop = asyncio.get_event_loop()
            loop.run_until_complete(r._register())

        return r


class SecureResource(BaseResource):
    """A secure base resource class"""

    @abstractmethod
    def _to_resource(self) -> Resource:
        pass

    @abstractmethod
    def _perms_to_actions(self, *args: str) -> List[Action]:
        pass

    async def _register_policy_async(self, *args: str):
        # if self._reg is not None:
        #     await asyncio.wait({self._reg})

        policy = PolicyResource(
            principals=[Resource(type=ResourceType.Function)],
            actions=self._perms_to_actions(*args),
            resources=[self._to_resource()],
        )
        try:
            await self._resources_stub.declare(
                resource_declare_request=ResourceDeclareRequest(resource=Resource(type=ResourceType.Policy),
                                                                policy=policy))
        except GRPCError as grpc_err:
            raise exception_from_grpc_error(grpc_err)

    def _register_policy(self, *args: str):
        loop = asyncio.get_event_loop()
        loop.run_until_complete(self._register_policy_async(*args))

