import asyncio
import contextlib
import functools
import inspect
import json
import logging

import botocore.awsrequest
from botocore.exceptions import (
    InvalidIMDSEndpointError,
    MetadataRetrievalError,
)
from botocore.utils import (
    DEFAULT_METADATA_SERVICE_TIMEOUT,
    METADATA_BASE_URL,
    RETRYABLE_HTTP_ERRORS,
    ArnParser,
    BadIMDSRequestError,
    ClientError,
    ContainerMetadataFetcher,
    HTTPClientError,
    IdentityCache,
    IMDSFetcher,
    IMDSRegionProvider,
    InstanceMetadataFetcher,
    InstanceMetadataRegionFetcher,
    PluginContext,
    ReadTimeoutError,
    S3ExpressIdentityCache,
    S3ExpressIdentityResolver,
    S3RegionRedirector,
    S3RegionRedirectorv2,
    get_environ_proxies,
    os,
    reset_plugin_context,
    resolve_imds_endpoint_mode,
    set_plugin_context,
)

import aiobotocore.httpsession

logger = logging.getLogger(__name__)


class _RefCountedSession(aiobotocore.httpsession.AIOHTTPSession):
    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)
        self.__ref_count = 0
        self.__lock = None

    @contextlib.asynccontextmanager
    async def acquire(self):
        if not self.__lock:
            self.__lock = asyncio.Lock()

        # ensure we have a session
        async with self.__lock:
            self.__ref_count += 1

            try:
                if self.__ref_count == 1:
                    await self.__aenter__()
            except BaseException:
                self.__ref_count -= 1
                raise

        try:
            yield self
        finally:
            async with self.__lock:
                if self.__ref_count == 1:
                    await self.__aexit__(None, None, None)

                self.__ref_count -= 1


class AioIMDSFetcher(IMDSFetcher):
    def __init__(
        self,
        timeout=DEFAULT_METADATA_SERVICE_TIMEOUT,  # noqa: E501, lgtm [py/missing-call-to-init]
        num_attempts=1,
        base_url=METADATA_BASE_URL,
        env=None,
        user_agent=None,
        config=None,
        session=None,
    ):
        self._timeout = timeout
        self._num_attempts = num_attempts
        if config is None:
            config = {}
        self._base_url = self._select_base_url(base_url, config)
        self._config = config

        if env is None:
            env = os.environ.copy()
        self._disabled = (
            env.get('AWS_EC2_METADATA_DISABLED', 'false').lower() == 'true'
        )
        self._imds_v1_disabled = config.get('ec2_metadata_v1_disabled')
        self._user_agent = user_agent

        self._session = session or _RefCountedSession(
            timeout=self._timeout,
            proxies=get_environ_proxies(self._base_url),
        )

    async def _fetch_metadata_token(self):
        self._assert_enabled()
        url = self._construct_url(self._TOKEN_PATH)
        headers = {
            'x-aws-ec2-metadata-token-ttl-seconds': self._TOKEN_TTL,
        }
        self._add_user_agent(headers)

        request = botocore.awsrequest.AWSRequest(
            method='PUT', url=url, headers=headers
        )

        async with self._session.acquire() as session:
            for i in range(self._num_attempts):
                try:
                    response = await session.send(request.prepare())
                    if response.status_code == 200:
                        return await response.text
                    elif response.status_code in (404, 403, 405):
                        return None
                    elif response.status_code in (400,):
                        raise BadIMDSRequestError(request)
                except ReadTimeoutError:
                    return None
                except RETRYABLE_HTTP_ERRORS as e:
                    logger.debug(
                        "Caught retryable HTTP exception while making metadata "
                        "service request to %s: %s",
                        url,
                        e,
                        exc_info=True,
                    )
                except HTTPClientError as e:
                    error = e.kwargs.get('error')
                    if (
                        error
                        and getattr(error, 'errno', None) == 8
                        or str(getattr(error, 'os_error', None))
                        == 'Domain name not found'
                    ):  # threaded vs async resolver
                        raise InvalidIMDSEndpointError(endpoint=url, error=e)
                    else:
                        raise

        return None

    async def _get_request(self, url_path, retry_func, token=None):
        self._assert_enabled()
        if not token:
            self._assert_v1_enabled()
        if retry_func is None:
            retry_func = self._default_retry
        url = self._construct_url(url_path)
        headers = {}
        if token is not None:
            headers['x-aws-ec2-metadata-token'] = token
        self._add_user_agent(headers)

        async with self._session.acquire() as session:
            for i in range(self._num_attempts):
                try:
                    request = botocore.awsrequest.AWSRequest(
                        method='GET', url=url, headers=headers
                    )
                    response = await session.send(request.prepare())
                    should_retry = retry_func(response)
                    if inspect.isawaitable(should_retry):
                        should_retry = await should_retry

                    if not should_retry:
                        return response
                except RETRYABLE_HTTP_ERRORS as e:
                    logger.debug(
                        "Caught retryable HTTP exception while making metadata "
                        "service request to %s: %s",
                        url,
                        e,
                        exc_info=True,
                    )
        raise self._RETRIES_EXCEEDED_ERROR_CLS()

    async def _default_retry(self, response):
        return await self._is_non_ok_response(
            response
        ) or await self._is_empty(response)

    async def _is_non_ok_response(self, response):
        if response.status_code != 200:
            await self._log_imds_response(response, 'non-200', log_body=True)
            return True
        return False

    async def _is_empty(self, response):
        if not await response.content:
            await self._log_imds_response(response, 'no body', log_body=True)
            return True
        return False

    async def _log_imds_response(
        self, response, reason_to_log, log_body=False
    ):
        statement = (
            "Metadata service returned %s response "
            "with status code of %s for url: %s"
        )
        logger_args = [reason_to_log, response.status_code, response.url]
        if log_body:
            statement += ", content body: %s"
            logger_args.append(await response.content)
        logger.debug(statement, *logger_args)


class AioInstanceMetadataFetcher(AioIMDSFetcher, InstanceMetadataFetcher):
    async def retrieve_iam_role_credentials(self):
        try:
            token = await self._fetch_metadata_token()
            role_name = await self._get_iam_role(token)
            credentials = await self._get_credentials(role_name, token)
            if self._contains_all_credential_fields(credentials):
                credentials = {
                    'role_name': role_name,
                    'access_key': credentials['AccessKeyId'],
                    'secret_key': credentials['SecretAccessKey'],
                    'token': credentials['Token'],
                    'expiry_time': credentials['Expiration'],
                }
                self._evaluate_expiration(credentials)
                return credentials
            else:
                if 'Code' in credentials and 'Message' in credentials:
                    logger.debug(
                        'Error response received when retrieving'
                        'credentials: %s.',
                        credentials,
                    )
                return {}
        except self._RETRIES_EXCEEDED_ERROR_CLS:
            logger.debug(
                "Max number of attempts exceeded (%s) when "
                "attempting to retrieve data from metadata service.",
                self._num_attempts,
            )
        except BadIMDSRequestError as e:
            logger.debug("Bad IMDS request: %s", e.request)
        return {}

    async def _get_iam_role(self, token=None):
        return await (
            await self._get_request(
                url_path=self._URL_PATH,
                retry_func=self._needs_retry_for_role_name,
                token=token,
            )
        ).text

    async def _get_credentials(self, role_name, token=None):
        r = await self._get_request(
            url_path=self._URL_PATH + role_name,
            retry_func=self._needs_retry_for_credentials,
            token=token,
        )
        return json.loads(await r.text)

    async def _is_invalid_json(self, response):
        try:
            json.loads(await response.text)
            return False
        except ValueError:
            await self._log_imds_response(response, 'invalid json')
            return True

    async def _needs_retry_for_role_name(self, response):
        return await self._is_non_ok_response(
            response
        ) or await self._is_empty(response)

    async def _needs_retry_for_credentials(self, response):
        return (
            await self._is_non_ok_response(response)
            or await self._is_empty(response)
            or await self._is_invalid_json(response)
        )


class AioIMDSRegionProvider(IMDSRegionProvider):
    async def provide(self):
        """Provide the region value from IMDS."""
        instance_region = await self._get_instance_metadata_region()
        return instance_region

    async def _get_instance_metadata_region(self):
        fetcher = self._get_fetcher()
        region = await fetcher.retrieve_region()
        return region

    def _create_fetcher(self):
        metadata_timeout = self._session.get_config_variable(
            'metadata_service_timeout'
        )
        metadata_num_attempts = self._session.get_config_variable(
            'metadata_service_num_attempts'
        )
        imds_config = {
            'ec2_metadata_service_endpoint': self._session.get_config_variable(
                'ec2_metadata_service_endpoint'
            ),
            'ec2_metadata_service_endpoint_mode': resolve_imds_endpoint_mode(
                self._session
            ),
            'ec2_metadata_v1_disabled': self._session.get_config_variable(
                'ec2_metadata_v1_disabled'
            ),
        }
        fetcher = AioInstanceMetadataRegionFetcher(
            timeout=metadata_timeout,
            num_attempts=metadata_num_attempts,
            env=self._environ,
            user_agent=self._session.user_agent(),
            config=imds_config,
        )
        return fetcher


class AioInstanceMetadataRegionFetcher(
    AioIMDSFetcher, InstanceMetadataRegionFetcher
):
    async def retrieve_region(self):
        try:
            region = await self._get_region()
            return region
        except self._RETRIES_EXCEEDED_ERROR_CLS:
            logger.debug(
                "Max number of attempts exceeded (%s) when "
                "attempting to retrieve data from metadata service.",
                self._num_attempts,
            )
        return None

    async def _get_region(self):
        token = await self._fetch_metadata_token()
        response = await self._get_request(
            url_path=self._URL_PATH,
            retry_func=self._default_retry,
            token=token,
        )
        availability_zone = await response.text
        region = availability_zone[:-1]
        return region


class AioIdentityCache(IdentityCache):
    async def get_credentials(self, **kwargs):
        callback = self.build_refresh_callback(**kwargs)
        metadata = await callback()
        credential_entry = self._credential_cls.create_from_metadata(
            metadata=metadata,
            refresh_using=callback,
            method=self.METHOD,
            advisory_timeout=45,
            mandatory_timeout=10,
        )
        return credential_entry


class AioS3ExpressIdentityCache(AioIdentityCache, S3ExpressIdentityCache):
    @functools.lru_cache(maxsize=100)
    def _get_credentials(self, bucket):
        return asyncio.create_task(super().get_credentials(bucket=bucket))

    async def get_credentials(self, bucket):
        # upstream uses `@functools.lru_cache(maxsize=100)` to cache credentials.
        # This is incompatible with async code.
        # We need to implement custom caching logic.

        return await self._get_credentials(bucket=bucket)

    def build_refresh_callback(self, bucket):
        async def refresher():
            response = await self._client.create_session(Bucket=bucket)
            creds = response['Credentials']
            expiration = self._serialize_if_needed(
                creds['Expiration'], iso=True
            )
            return {
                "access_key": creds['AccessKeyId'],
                "secret_key": creds['SecretAccessKey'],
                "token": creds['SessionToken'],
                "expiry_time": expiration,
            }

        return refresher


class AioS3ExpressIdentityResolver(S3ExpressIdentityResolver):
    def __init__(self, client, credential_cls, cache=None):
        super().__init__(client, credential_cls, cache)

        if cache is None:
            cache = AioS3ExpressIdentityCache(self._client, credential_cls)
        self._cache = cache


class AioS3RegionRedirectorv2(S3RegionRedirectorv2):
    async def redirect_from_error(
        self,
        request_dict,
        response,
        operation,
        **kwargs,
    ):
        """
        An S3 request sent to the wrong region will return an error that
        contains the endpoint the request should be sent to. This handler
        will add the redirect information to the signing context and then
        redirect the request.
        """
        if response is None:
            # This could be none if there was a ConnectionError or other
            # transport error.
            return

        redirect_ctx = request_dict.get('context', {}).get('s3_redirect', {})
        if ArnParser.is_arn(redirect_ctx.get('bucket')):
            logger.debug(
                'S3 request was previously for an Accesspoint ARN, not '
                'redirecting.'
            )
            return

        if redirect_ctx.get('redirected'):
            logger.debug(
                'S3 request was previously redirected, not redirecting.'
            )
            return

        error = response[1].get('Error', {})
        error_code = error.get('Code')
        response_metadata = response[1].get('ResponseMetadata', {})

        # We have to account for 400 responses because
        # if we sign a Head* request with the wrong region,
        # we'll get a 400 Bad Request but we won't get a
        # body saying it's an "AuthorizationHeaderMalformed".
        is_special_head_object = (
            error_code in ('301', '400') and operation.name == 'HeadObject'
        )
        is_special_head_bucket = (
            error_code in ('301', '400')
            and operation.name == 'HeadBucket'
            and 'x-amz-bucket-region'
            in response_metadata.get('HTTPHeaders', {})
        )
        is_wrong_signing_region = (
            error_code == 'AuthorizationHeaderMalformed' and 'Region' in error
        )
        is_redirect_status = response[0] is not None and response[
            0
        ].status_code in (301, 302, 307)
        is_permanent_redirect = error_code == 'PermanentRedirect'
        is_opt_in_region_redirect = (
            error_code == 'IllegalLocationConstraintException'
            and operation.name != 'CreateBucket'
        )
        if not any(
            [
                is_special_head_object,
                is_wrong_signing_region,
                is_permanent_redirect,
                is_special_head_bucket,
                is_redirect_status,
                is_opt_in_region_redirect,
            ]
        ):
            return

        bucket = request_dict['context']['s3_redirect']['bucket']
        client_region = request_dict['context'].get('client_region')
        new_region = await self.get_bucket_region(bucket, response)

        if new_region is None:
            logger.debug(
                "S3 client configured for region %s but the "
                "bucket %s is not in that region and the proper region "
                "could not be automatically determined.",
                client_region,
                bucket,
            )
            return

        logger.debug(
            "S3 client configured for region %s but the bucket %s "
            "is in region %s; Please configure the proper region to "
            "avoid multiple unnecessary redirects and signing attempts.",
            client_region,
            bucket,
            new_region,
        )
        # Adding the new region to _cache will make construct_endpoint() to
        # use the new region as value for the AWS::Region builtin parameter.
        self._cache[bucket] = new_region

        # Re-resolve endpoint with new region and modify request_dict with
        # the new URL, auth scheme, and signing context.
        ep_resolver = self._client._ruleset_resolver
        ep_info = await ep_resolver.construct_endpoint(
            operation_model=operation,
            call_args=request_dict['context']['s3_redirect']['params'],
            request_context=request_dict['context'],
        )
        request_dict['url'] = self.set_request_url(
            request_dict['url'], ep_info.url
        )
        request_dict['context']['s3_redirect']['redirected'] = True
        auth_schemes = ep_info.properties.get('authSchemes')
        if auth_schemes is not None:
            auth_info = ep_resolver.auth_schemes_to_signing_ctx(auth_schemes)
            auth_type, signing_context = auth_info
            request_dict['context']['auth_type'] = auth_type
            request_dict['context']['signing'] = {
                **request_dict['context'].get('signing', {}),
                **signing_context,
            }

        # Return 0 so it doesn't wait to retry
        return 0

    async def get_bucket_region(self, bucket, response):
        """
        There are multiple potential sources for the new region to redirect to,
        but they aren't all universally available for use. This will try to
        find region from response elements, but will fall back to calling
        HEAD on the bucket if all else fails.
        :param bucket: The bucket to find the region for. This is necessary if
            the region is not available in the error response.
        :param response: A response representing a service request that failed
            due to incorrect region configuration.
        """
        # First try to source the region from the headers.
        service_response = response[1]
        response_headers = service_response['ResponseMetadata']['HTTPHeaders']
        if 'x-amz-bucket-region' in response_headers:
            return response_headers['x-amz-bucket-region']

        # Next, check the error body
        region = service_response.get('Error', {}).get('Region', None)
        if region is not None:
            return region

        # Finally, HEAD the bucket. No other choice sadly.
        try:
            # NOTE: we don't need to aenter/aexit as we have a ref to the base client
            response = await self._client.head_bucket(Bucket=bucket)
            headers = response['ResponseMetadata']['HTTPHeaders']
        except ClientError as e:
            headers = e.response['ResponseMetadata']['HTTPHeaders']

        region = headers.get('x-amz-bucket-region', None)
        return region


class AioS3RegionRedirector(S3RegionRedirector):
    async def redirect_from_error(
        self, request_dict, response, operation, **kwargs
    ):
        if response is None:
            # This could be none if there was a ConnectionError or other
            # transport error.
            return

        if self._is_s3_accesspoint(request_dict.get('context', {})):
            logger.debug(
                'S3 request was previously to an accesspoint, not redirecting.'
            )
            return

        if request_dict.get('context', {}).get('s3_redirected'):
            logger.debug(
                'S3 request was previously redirected, not redirecting.'
            )
            return

        error = response[1].get('Error', {})
        error_code = error.get('Code')
        response_metadata = response[1].get('ResponseMetadata', {})

        # We have to account for 400 responses because
        # if we sign a Head* request with the wrong region,
        # we'll get a 400 Bad Request but we won't get a
        # body saying it's an "AuthorizationHeaderMalformed".
        is_special_head_object = (
            error_code in ('301', '400') and operation.name == 'HeadObject'
        )
        is_special_head_bucket = (
            error_code in ('301', '400')
            and operation.name == 'HeadBucket'
            and 'x-amz-bucket-region'
            in response_metadata.get('HTTPHeaders', {})
        )
        is_wrong_signing_region = (
            error_code == 'AuthorizationHeaderMalformed' and 'Region' in error
        )
        is_redirect_status = response[0] is not None and response[
            0
        ].status_code in (301, 302, 307)
        is_permanent_redirect = error_code == 'PermanentRedirect'
        if not any(
            [
                is_special_head_object,
                is_wrong_signing_region,
                is_permanent_redirect,
                is_special_head_bucket,
                is_redirect_status,
            ]
        ):
            return

        bucket = request_dict['context']['signing']['bucket']
        client_region = request_dict['context'].get('client_region')
        new_region = await self.get_bucket_region(bucket, response)

        if new_region is None:
            logger.debug(
                "S3 client configured for region %s but the bucket %s is not "
                "in that region and the proper region could not be "
                "automatically determined.",
                client_region,
                bucket,
            )
            return

        logger.debug(
            "S3 client configured for region %s but the bucket %s is in region"
            " %s; Please configure the proper region to avoid multiple "
            "unnecessary redirects and signing attempts.",
            client_region,
            bucket,
            new_region,
        )
        endpoint = self._endpoint_resolver.resolve('s3', new_region)
        endpoint = endpoint['endpoint_url']

        signing_context = {
            'region': new_region,
            'bucket': bucket,
            'endpoint': endpoint,
        }
        request_dict['context']['signing'] = signing_context

        self._cache[bucket] = signing_context
        self.set_request_url(request_dict, request_dict['context'])

        request_dict['context']['s3_redirected'] = True

        # Return 0 so it doesn't wait to retry
        return 0

    async def get_bucket_region(self, bucket, response):
        # First try to source the region from the headers.
        service_response = response[1]
        response_headers = service_response['ResponseMetadata']['HTTPHeaders']
        if 'x-amz-bucket-region' in response_headers:
            return response_headers['x-amz-bucket-region']

        # Next, check the error body
        region = service_response.get('Error', {}).get('Region', None)
        if region is not None:
            return region

        # Finally, HEAD the bucket. No other choice sadly.
        try:
            # NOTE: we don't need to aenter/aexit as we have a ref to the base client
            response = await self._client.head_bucket(Bucket=bucket)
            headers = response['ResponseMetadata']['HTTPHeaders']
        except ClientError as e:
            headers = e.response['ResponseMetadata']['HTTPHeaders']

        region = headers.get('x-amz-bucket-region', None)
        return region


class AioContainerMetadataFetcher(ContainerMetadataFetcher):
    def __init__(self, session=None, sleep=asyncio.sleep):  # noqa: E501, lgtm [py/missing-call-to-init]
        if session is None:
            session = _RefCountedSession(timeout=self.TIMEOUT_SECONDS)
        self._session = session
        self._sleep = sleep

    async def retrieve_full_uri(self, full_url, headers=None):
        self._validate_allowed_url(full_url)
        return await self._retrieve_credentials(full_url, headers)

    async def retrieve_uri(self, relative_uri):
        """Retrieve JSON metadata from container metadata.

        :type relative_uri: str
        :param relative_uri: A relative URI, e.g "/foo/bar?id=123"

        :return: The parsed JSON response.

        """
        full_url = self.full_url(relative_uri)
        return await self._retrieve_credentials(full_url)

    async def _retrieve_credentials(self, full_url, extra_headers=None):
        headers = {'Accept': 'application/json'}
        if extra_headers is not None:
            headers.update(extra_headers)
        attempts = 0
        while True:
            try:
                return await self._get_response(
                    full_url, headers, self.TIMEOUT_SECONDS
                )
            except MetadataRetrievalError as e:
                logger.debug(
                    "Received error when attempting to retrieve "
                    "container metadata: %s",
                    e,
                    exc_info=True,
                )
                await self._sleep(self.SLEEP_TIME)
                attempts += 1
                if attempts >= self.RETRY_ATTEMPTS:
                    raise

    async def _get_response(self, full_url, headers, timeout):
        try:
            async with self._session.acquire() as session:
                AWSRequest = botocore.awsrequest.AWSRequest
                request = AWSRequest(
                    method='GET', url=full_url, headers=headers
                )
                response = await session.send(request.prepare())
                response_text = (await response.content).decode('utf-8')

                if response.status_code != 200:
                    raise MetadataRetrievalError(
                        error_msg=(
                            f"Received non 200 response {response.status_code} "
                            f"from container metadata: {response_text}"
                        )
                    )
                try:
                    return json.loads(response_text)
                except ValueError:
                    error_msg = "Unable to parse JSON returned from container metadata services"
                    logger.debug('%s:%s', error_msg, response_text)
                    raise MetadataRetrievalError(error_msg=error_msg)

        except RETRYABLE_HTTP_ERRORS as e:
            error_msg = (
                "Received error when attempting to retrieve "
                f"container metadata: {e}"
            )
            raise MetadataRetrievalError(error_msg=error_msg)


@contextlib.asynccontextmanager
async def create_nested_client(session, service_name, **kwargs):
    """Create a nested client with plugin context disabled.

    If a client is created from within a plugin based on the environment variable,
    an infinite loop could arise. Any clients created from within another client
    must use this method to prevent infinite loops.

    This is the async version of botocore.utils.create_nested_client that works
    with aiobotocore's async session.

    Usage:
        async with create_nested_client(session, 'sts', region_name='us-east-1') as client:
            response = await client.assume_role(...)
    """
    # Set plugin context to disabled
    ctx = PluginContext(plugins="DISABLED")
    token = set_plugin_context(ctx)

    try:
        # Create client context
        async with session.create_client(service_name, **kwargs) as client:
            # Reset plugin context immediately after client creation, matching botocore behavior
            reset_plugin_context(token)
            token = None

            yield client
    finally:
        if token:
            reset_plugin_context(token)
