from datetime import datetime, timedelta
from typing import Optional

import pytest

from hivemind.proto import dht_pb2
from hivemind.proto.auth_pb2 import AccessToken
from hivemind.utils.auth import AuthRPCWrapper, AuthRole, TokenAuthorizerBase
from hivemind.utils.crypto import RSAPrivateKey
from hivemind.utils.logging import get_logger


logger = get_logger(__name__)


class MockAuthorizer(TokenAuthorizerBase):
    _authority_private_key = None
    _authority_public_key = None

    def __init__(self, local_private_key: Optional[RSAPrivateKey], username: str='mock'):
        super().__init__(local_private_key)

        self._username = username
        self._authority_public_key = None

    async def get_token(self) -> AccessToken:
        if MockAuthorizer._authority_private_key is None:
            MockAuthorizer._authority_private_key = RSAPrivateKey()

        self._authority_public_key = MockAuthorizer._authority_private_key.get_public_key()

        token = AccessToken(username=self._username,
                            public_key=self.local_public_key.to_bytes(),
                            expiration_time=str(datetime.utcnow() + timedelta(minutes=1)))
        token.signature = MockAuthorizer._authority_private_key.sign(self._token_to_bytes(token))
        return token

    def is_token_valid(self, access_token: AccessToken) -> bool:
        data = self._token_to_bytes(access_token)
        if not self._authority_public_key.verify(data, access_token.signature):
            logger.exception('Access token has invalid signature')
            return False

        try:
            expiration_time = datetime.fromisoformat(access_token.expiration_time)
        except ValueError:
            logger.exception(
                f'datetime.fromisoformat() failed to parse expiration time: {access_token.expiration_time}')
            return False
        if expiration_time.tzinfo is not None:
            logger.exception(f'Expected to have no timezone for expiration time: {access_token.expiration_time}')
            return False
        if expiration_time < datetime.utcnow():
            logger.exception('Access token has expired')
            return False

        return True

    _MAX_LATENCY = timedelta(minutes=1)

    def does_token_need_refreshing(self, access_token: AccessToken) -> bool:
        expiration_time = datetime.fromisoformat(access_token.expiration_time)
        return expiration_time < datetime.utcnow() + self._MAX_LATENCY

    @staticmethod
    def _token_to_bytes(access_token: AccessToken) -> bytes:
        return f'{access_token.username} {access_token.public_key} {access_token.expiration_time}'.encode()


@pytest.mark.asyncio
async def test_valid_request_and_response():
    client_authorizer = MockAuthorizer(RSAPrivateKey())
    service_authorizer = MockAuthorizer(RSAPrivateKey())

    request = dht_pb2.PingRequest()
    request.peer.endpoint = '127.0.0.1:7777'
    await client_authorizer.sign_request(request, service_authorizer.local_public_key)
    assert await service_authorizer.validate_request(request)

    response = dht_pb2.PingResponse()
    response.sender_endpoint = '127.0.0.1:31337'
    await service_authorizer.sign_response(response, request)
    assert await client_authorizer.validate_response(response, request)


@pytest.mark.asyncio
async def test_invalid_access_token():
    client_authorizer = MockAuthorizer(RSAPrivateKey())
    service_authorizer = MockAuthorizer(RSAPrivateKey())

    request = dht_pb2.PingRequest()
    request.peer.endpoint = '127.0.0.1:7777'
    await client_authorizer.sign_request(request, service_authorizer.local_public_key)

    # Break the access token signature
    request.auth.client_access_token.signature = b'broken'

    assert not await service_authorizer.validate_request(request)

    response = dht_pb2.PingResponse()
    response.sender_endpoint = '127.0.0.1:31337'
    await service_authorizer.sign_response(response, request)

    # Break the access token signature
    response.auth.service_access_token.signature = b'broken'

    assert not await client_authorizer.validate_response(response, request)


@pytest.mark.asyncio
async def test_invalid_signatures():
    client_authorizer = MockAuthorizer(RSAPrivateKey())
    service_authorizer = MockAuthorizer(RSAPrivateKey())

    request = dht_pb2.PingRequest()
    request.peer.endpoint = '127.0.0.1:7777'
    await client_authorizer.sign_request(request, service_authorizer.local_public_key)

    # A man-in-the-middle attacker changes the request content
    request.peer.endpoint = '127.0.0.2:7777'

    assert not await service_authorizer.validate_request(request)

    response = dht_pb2.PingResponse()
    response.sender_endpoint = '127.0.0.1:31337'
    await service_authorizer.sign_response(response, request)

    # A man-in-the-middle attacker changes the response content
    response.sender_endpoint = '127.0.0.2:31337'

    assert not await client_authorizer.validate_response(response, request)


@pytest.mark.asyncio
async def test_auth_rpc_wrapper():
    class Servicer:
        async def rpc_increment(self, request: dht_pb2.PingRequest) -> dht_pb2.PingResponse:
            assert request.peer.endpoint == '127.0.0.1:1111'
            assert request.auth.client_access_token.username == 'alice'

            response = dht_pb2.PingResponse()
            response.sender_endpoint = '127.0.0.1:2222'
            return response

    class Client:
        def __init__(self, servicer: Servicer):
            self._servicer = servicer

        async def rpc_increment(self, request: dht_pb2.PingRequest) -> dht_pb2.PingResponse:
            return await self._servicer.rpc_increment(request)

    servicer = AuthRPCWrapper(Servicer(), AuthRole.SERVICER, MockAuthorizer(RSAPrivateKey(), 'bob'))
    client = AuthRPCWrapper(Client(servicer), AuthRole.CLIENT, MockAuthorizer(RSAPrivateKey(), 'alice'))

    request = dht_pb2.PingRequest()
    request.peer.endpoint = '127.0.0.1:1111'

    response = await client.rpc_increment(request)

    assert response.sender_endpoint == '127.0.0.1:2222'
    assert response.auth.service_access_token.username == 'bob'