# Copyright 2013 - Mirantis, Inc.
# Copyright 2016 - Brocade Communications Systems, Inc.
#
#    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.

import base64

from mistral_lib.actions import context as lib_ctx
from mistral_lib import serialization
from oslo_config import cfg
from oslo_context import context as oslo_context
from oslo_log import log as logging
import oslo_messaging as messaging
from oslo_serialization import jsonutils
from osprofiler import profiler
import pecan
from pecan import hooks

from mistral import auth
from mistral import exceptions as exc
from mistral_lib import utils


LOG = logging.getLogger(__name__)

CONF = cfg.CONF

_CTX_THREAD_LOCAL_NAME = "MISTRAL_APP_CTX_THREAD_LOCAL"
ALLOWED_WITHOUT_AUTH = ['/', '/v2/', '/workflowv2/', '/workflowv2/v2/']


class MistralContext(oslo_context.RequestContext):
    def __init__(self, auth_uri=None, auth_cacert=None, insecure=False,
                 service_catalog=None, region_name=None, is_trust_scoped=False,
                 redelivered=False, expires_at=None, trust_id=None,
                 is_target=False, **kwargs):
        self.auth_uri = auth_uri
        self.auth_cacert = auth_cacert
        self.insecure = insecure
        self.service_catalog = service_catalog
        self.region_name = region_name
        self.is_trust_scoped = is_trust_scoped
        self.redelivered = redelivered
        self.expires_at = expires_at
        self.trust_id = trust_id
        self.is_target = is_target

        # We still use Mistral thread local variable. Maybe could consider
        # using the variable provided by oslo_context in future.
        super(MistralContext, self).__init__(overwrite=False, **kwargs)

    def to_dict(self):
        """Return a dictionary of context attributes."""
        ctx_dict = super(MistralContext, self).to_dict()
        ctx_dict.update(
            {
                'user_name': self.user_name,
                'project_name': self.project_name,
                'domain_name': self.domain_name,
                'user_domain_name': self.user_domain_name,
                'project_domain_name': self.project_domain_name,
                'auth_uri': self.auth_uri,
                'auth_cacert': self.auth_cacert,
                'insecure': self.insecure,
                'service_catalog': self.service_catalog,
                'region_name': self.region_name,
                'is_trust_scoped': self.is_trust_scoped,
                'redelivered': self.redelivered,
                'expires_at': self.expires_at,
                'trust_id': self.trust_id,
                'is_target': self.is_target,
            }
        )

        return ctx_dict

    @classmethod
    def from_dict(cls, values, **kwargs):
        """Construct a context object from a provided dictionary."""
        kwargs.setdefault('auth_uri', values.get('auth_uri'))
        kwargs.setdefault('auth_cacert', values.get('auth_cacert'))
        kwargs.setdefault('insecure', values.get('insecure', False))
        kwargs.setdefault('service_catalog', values.get('service_catalog'))
        kwargs.setdefault('region_name', values.get('region_name'))
        kwargs.setdefault(
            'is_trust_scoped', values.get('is_trust_scoped', False)
        )
        kwargs.setdefault('redelivered', values.get('redelivered', False))
        kwargs.setdefault('expires_at', values.get('expires_at'))
        kwargs.setdefault('trust_id', values.get('trust_id'))
        kwargs.setdefault('is_target', values.get('is_target', False))

        return super(MistralContext, cls).from_dict(values, **kwargs)

    @classmethod
    def from_environ(cls, headers, env):
        kwargs = _extract_mistral_auth_params(headers)

        token_info = env.get('keystone.token_info', {})
        if not kwargs['is_target']:
            kwargs['service_catalog'] = token_info.get('token', {})
        kwargs['expires_at'] = (token_info['token']['expires_at']
                                if token_info else None)

        context = super(MistralContext, cls).from_environ(env, **kwargs)
        context.is_admin = True if 'admin' in context.roles else False

        return context


def has_ctx():
    return utils.has_thread_local(_CTX_THREAD_LOCAL_NAME)


def ctx():
    if not has_ctx():
        raise exc.ApplicationContextNotFoundException()

    return utils.get_thread_local(_CTX_THREAD_LOCAL_NAME)


def set_ctx(new_ctx):
    utils.set_thread_local(_CTX_THREAD_LOCAL_NAME, new_ctx)


def _extract_mistral_auth_params(headers):
    service_catalog = None

    if headers.get("X-Target-Auth-Uri"):
        insecure_header = headers.get('X-Target-Insecure', 'False')
        if insecure_header == 'False':
            insecure = False
        elif insecure_header == 'True':
            insecure = True
        else:
            raise (exc.MistralException(
                'X-Target-Insecure must be either "True", "False" or not '
                'provided. The default is "False".'))

        params = {
            # TODO(akovi): Target cert not handled yet
            'auth_cacert': None,
            'insecure': insecure,
            'auth_token': headers.get('X-Target-Auth-Token'),
            'auth_uri': headers.get('X-Target-Auth-Uri'),
            # TODO(tkajinam): Remove this once oslo.context >= 4.0.0 becomes
            #                 avaialble
            'tenant': headers.get('X-Target-Project-Id'),
            'project_id': headers.get('X-Target-Project-Id'),
            'user': headers.get('X-Target-User-Id'),
            'user_name': headers.get('X-Target-User-Name'),
            'region_name': headers.get('X-Target-Region-Name'),
            'is_target': True
        }
        if not params['auth_token']:
            raise (exc.MistralException(
                'Target auth URI (X-Target-Auth-Uri) target auth token '
                '(X-Target-Auth-Token) must be present'))

        # It's possible that target service catalog is not provided, in this
        # case, Mistral needs to get target service catalog dynamically when
        # talking to target openstack deployment later on.
        service_catalog = _extract_service_catalog_from_headers(
            headers
        )
    else:
        params = {
            'auth_uri': CONF.keystone_authtoken.www_authenticate_uri,
            'auth_cacert': CONF.keystone_authtoken.cafile,
            'insecure': False,
            'region_name': headers.get('X-Region-Name'),
            'is_target': False
        }

    params['service_catalog'] = service_catalog

    return params


def _extract_service_catalog_from_headers(headers):
    target_service_catalog_header = headers.get(
        'X-Target-Service-Catalog')
    if target_service_catalog_header:
        decoded_catalog = base64.b64decode(
            target_service_catalog_header).decode()
        return jsonutils.loads(decoded_catalog)
    else:
        return None


class RpcContextSerializer(messaging.Serializer):
    def __init__(self, entity_serializer=None):
        self.entity_serializer = (
            entity_serializer or serialization.get_polymorphic_serializer()
        )

    def serialize_entity(self, context, entity):
        if not self.entity_serializer:
            return entity

        return self.entity_serializer.serialize(entity)

    def deserialize_entity(self, context, entity):
        if not self.entity_serializer:
            return entity

        return self.entity_serializer.deserialize(entity)

    def serialize_context(self, context):
        ctx = context.to_dict()

        pfr = profiler.get()

        if pfr:
            ctx['trace_info'] = {
                "hmac_key": pfr.hmac_key,
                "base_id": pfr.get_base_id(),
                "parent_id": pfr.get_id()
            }

        return ctx

    def deserialize_context(self, context):
        trace_info = context.pop('trace_info', None)

        if trace_info:
            profiler.init(**trace_info)

        ctx = MistralContext.from_dict(context)

        set_ctx(ctx)

        return ctx


class AuthHook(hooks.PecanHook):
    def before(self, state):
        if state.request.path in ALLOWED_WITHOUT_AUTH:
            return

        if not CONF.pecan.auth_enable:
            return

        try:
            auth_handler = auth.get_auth_handler()
            auth_handler.authenticate(state.request)
        except Exception as e:
            msg = "Failed to validate access token: %s" % str(e)

            LOG.exception(msg)

            pecan.abort(
                status_code=401,
                detail=msg,
                headers={'Server-Error-Message': msg, "WWW-Authenticate": msg}
            )


class ContextHook(hooks.PecanHook):
    def before(self, state):
        context = MistralContext.from_environ(
            state.request.headers, state.request.environ
        )

        set_ctx(context)

    def after(self, state):
        set_ctx(None)


def create_action_context(execution_ctx):

    context = ctx()

    security_ctx = lib_ctx.SecurityContext(
        auth_cacert=context.auth_cacert,
        auth_token=context.auth_token,
        auth_uri=context.auth_uri,
        expires_at=context.expires_at,
        insecure=context.insecure,
        is_target=context.is_target,
        is_trust_scoped=context.is_trust_scoped,
        project_id=context.project_id,
        project_name=context.project_name,
        user_name=context.user_name,
        redelivered=context.redelivered,
        region_name=context.region_name,
        service_catalog=context.service_catalog,
        trust_id=context.trust_id,
    )

    ex_ctx = lib_ctx.ExecutionContext(**execution_ctx)

    return lib_ctx.ActionContext(security_ctx, ex_ctx)
