# Copyright 2022-2023 ETSI TeraFlowSDN - TFS OSG (https://tfs.etsi.org/)
#
# 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 grpc, json, logging, random, uuid
from typing import Optional
from common.method_wrappers.Decorator import MetricsPool, safe_and_metered_rpc_method
from common.method_wrappers.ServiceExceptions import (
    AlreadyExistsException, InvalidArgumentException, NotFoundException, NotImplementedException,
    OperationFailedException)
from common.proto.context_pb2 import Connection, Empty, Service, ServiceId, ServiceStatusEnum, ServiceTypeEnum
from common.proto.pathcomp_pb2 import PathCompRequest
from common.proto.service_pb2_grpc import ServiceServiceServicer
from common.tools.context_queries.Service import get_service_by_id
from common.tools.grpc.Tools import grpc_message_to_json, grpc_message_to_json_string
from context.client.ContextClient import ContextClient
from pathcomp.frontend.client.PathCompClient import PathCompClient
from service.service.tools.ConnectionToString import connection_to_string
from .service_handler_api.ServiceHandlerFactory import ServiceHandlerFactory
from .task_scheduler.TaskScheduler import TasksScheduler

LOGGER = logging.getLogger(__name__)

METRICS_POOL = MetricsPool('Service', 'RPC')

class ServiceServiceServicerImpl(ServiceServiceServicer):
    def __init__(self, service_handler_factory : ServiceHandlerFactory) -> None:
        LOGGER.debug('Creating Servicer...')
        self.service_handler_factory = service_handler_factory
        LOGGER.debug('Servicer Created')

    @safe_and_metered_rpc_method(METRICS_POOL, LOGGER)
    def CreateService(self, request : Service, context : grpc.ServicerContext) -> ServiceId:
        if len(request.service_endpoint_ids) > 0:
            unexpected_endpoints = []
            for service_endpoint_id in request.service_endpoint_ids:
                unexpected_endpoints.append(grpc_message_to_json(service_endpoint_id))
            str_unexpected_endpoints = json.dumps(unexpected_endpoints, sort_keys=True)
            raise InvalidArgumentException(
                'service.service_endpoint_ids', str_unexpected_endpoints,
                extra_details='RPC method CreateService does not accept Endpoints. '\
                              'Endpoints should be configured after creating the service.')

        if len(request.service_constraints) > 0:
            unexpected_constraints = []
            for service_constraint in request.service_constraints:
                unexpected_constraints.append(grpc_message_to_json(service_constraint))
            str_unexpected_constraints = json.dumps(unexpected_constraints, sort_keys=True)
            raise InvalidArgumentException(
                'service.service_constraints', str_unexpected_constraints,
                extra_details='RPC method CreateService does not accept Constraints. '\
                              'Constraints should be configured after creating the service.')

        if len(request.service_config.config_rules) > 0:
            unexpected_config_rules = grpc_message_to_json(request.service_config)
            unexpected_config_rules = unexpected_config_rules['config_rules']
            str_unexpected_config_rules = json.dumps(unexpected_config_rules, sort_keys=True)
            raise InvalidArgumentException(
                'service.service_config.config_rules', str_unexpected_config_rules,
                extra_details='RPC method CreateService does not accept Config Rules. '\
                              'Config Rules should be configured after creating the service.')

        # check that service does not exist
        context_client = ContextClient()
        current_service = get_service_by_id(
            context_client, request.service_id, rw_copy=False,
            include_config_rules=False, include_constraints=False, include_endpoint_ids=False)
        if current_service is not None:
            context_uuid = request.service_id.context_id.context_uuid.uuid
            service_uuid = request.service_id.service_uuid.uuid
            raise AlreadyExistsException(
                'Service', service_uuid, extra_details='context_uuid={:s}'.format(str(context_uuid)))

        # just create the service in the Context database to lock the service_id
        # update will perform changes on the resources
        service_id = context_client.SetService(request)
        return service_id

    @safe_and_metered_rpc_method(METRICS_POOL, LOGGER)
    def UpdateService(self, request : Service, context : grpc.ServicerContext) -> ServiceId:
        # Set service status to "SERVICESTATUS_PLANNED" to ensure rest of components are aware the service is
        # being modified.
        context_client = ContextClient()
        _service : Optional[Service] = get_service_by_id(
            context_client, request.service_id, rw_copy=False,
            include_config_rules=False, include_constraints=False, include_endpoint_ids=False)
        service = Service()
        service.CopyFrom(request if _service is None else _service)
        if service.service_type == ServiceTypeEnum.SERVICETYPE_UNKNOWN:                     # pylint: disable=no-member
            service.service_type = request.service_type                                     # pylint: disable=no-member
        service.service_status.service_status = ServiceStatusEnum.SERVICESTATUS_PLANNED     # pylint: disable=no-member

        del service.service_endpoint_ids[:] # pylint: disable=no-member
        for endpoint_id in request.service_endpoint_ids:
            service.service_endpoint_ids.add().CopyFrom(endpoint_id)    # pylint: disable=no-member

        del service.service_constraints[:]  # pylint: disable=no-member
        for constraint in request.service_constraints:
            service.service_constraints.add().CopyFrom(constraint)  # pylint: disable=no-member

        del service.service_config.config_rules[:]  # pylint: disable=no-member
        for config_rule in request.service_config.config_rules:
            service.service_config.config_rules.add().CopyFrom(config_rule) # pylint: disable=no-member

        service_id_with_uuids = context_client.SetService(service)

        # PathComp requires endpoints, constraints and config rules
        service_with_uuids = get_service_by_id(
            context_client, service_id_with_uuids, rw_copy=False,
            include_config_rules=True, include_constraints=True, include_endpoint_ids=True)

        num_disjoint_paths = 0
        for constraint in request.service_constraints:
            if constraint.WhichOneof('constraint') == 'sla_availability':
                num_disjoint_paths = constraint.sla_availability.num_disjoint_paths
                break

        num_disjoint_paths = 1 if num_disjoint_paths is None or num_disjoint_paths == 0 else num_disjoint_paths
        num_expected_endpoints = num_disjoint_paths * 2

        tasks_scheduler = TasksScheduler(self.service_handler_factory)
        if len(service_with_uuids.service_endpoint_ids) >= num_expected_endpoints:
            pathcomp_request = PathCompRequest()
            pathcomp_request.services.append(service_with_uuids)    # pylint: disable=no-member

            if num_disjoint_paths is None or num_disjoint_paths in {0, 1}:
                pathcomp_request.shortest_path.Clear()              # pylint: disable=no-member
            else:
                pathcomp_request.k_disjoint_path.num_disjoint = num_disjoint_paths  # pylint: disable=no-member

            LOGGER.debug('pathcomp_request={:s}'.format(grpc_message_to_json_string(pathcomp_request)))
            pathcomp = PathCompClient()
            pathcomp_reply = pathcomp.Compute(pathcomp_request)
            pathcomp.close()
            LOGGER.debug('pathcomp_reply={:s}'.format(grpc_message_to_json_string(pathcomp_reply)))

            # Feed TaskScheduler with this path computation reply. TaskScheduler identifies inter-dependencies among
            # the services and connections retrieved and produces a schedule of tasks (an ordered list of tasks to be
            # executed) to implement the requested create/update operation.
            tasks_scheduler.compose_from_pathcompreply(pathcomp_reply, is_delete=False)

        tasks_scheduler.execute_all()
        return service_with_uuids.service_id

    @safe_and_metered_rpc_method(METRICS_POOL, LOGGER)
    def DeleteService(self, request : ServiceId, context : grpc.ServicerContext) -> Empty:
        context_client = ContextClient()

        # Set service status to "SERVICESTATUS_PENDING_REMOVAL" to ensure rest of components are aware the service is
        # being modified.
        service : Optional[Service] = get_service_by_id(context_client, request, rw_copy=True)
        if service is None: raise Exception('Service({:s}) not found'.format(grpc_message_to_json_string(request)))
        # pylint: disable=no-member
        service.service_status.service_status = ServiceStatusEnum.SERVICESTATUS_PENDING_REMOVAL
        context_client.SetService(service)

        # Feed TaskScheduler with this service and the sub-services and sub-connections related to this service.
        # TaskScheduler identifies inter-dependencies among them and produces a schedule of tasks (an ordered list of
        # tasks to be executed) to implement the requested delete operation.
        tasks_scheduler = TasksScheduler(self.service_handler_factory)
        tasks_scheduler.compose_from_service(service, is_delete=True)
        tasks_scheduler.execute_all()
        return Empty()

    @safe_and_metered_rpc_method(METRICS_POOL, LOGGER)
    def RecomputeConnections(self, request : Service, context : grpc.ServicerContext) -> Empty:
        if len(request.service_endpoint_ids) > 0:
            raise NotImplementedException('update-endpoints')

        if len(request.service_constraints) > 0:
            raise NotImplementedException('update-constraints')

        if len(request.service_config.config_rules) > 0:
            raise NotImplementedException('update-config-rules')

        context_client = ContextClient()

        updated_service : Optional[Service] = get_service_by_id(
            context_client, request.service_id, rw_copy=True,
            include_config_rules=False, include_constraints=False, include_endpoint_ids=False)

        if updated_service is None:
            raise NotFoundException('service', request.service_id.service_uuid.uuid)

        # pylint: disable=no-member
        if updated_service.service_type == ServiceTypeEnum.SERVICETYPE_UNKNOWN:
            raise InvalidArgumentException(
                'request.service_type', ServiceTypeEnum.Name(updated_service.service_type)
            )

        # Set service status to "SERVICESTATUS_UPDATING" to ensure rest of components are aware the service is
        # being modified.
        # pylint: disable=no-member
        updated_service.service_status.service_status = ServiceStatusEnum.SERVICESTATUS_UPDATING

        # Update endpoints
        # pylint: disable=no-member
        #del updated_service.service_endpoint_ids[:]
        #updated_service.service_endpoint_ids.extend(request.service_endpoint_ids)

        # Update constraints
        # pylint: disable=no-member
        #del updated_service.service_constraints[:]
        #updated_service.service_constraints.extend(request.service_constraints)

        # Update config rules
        # pylint: disable=no-member
        #del updated_service.service_config.config_rules[:]
        #updated_service.service_config.config_rules.extend(request.service_config.config_rules)

        updated_service_id_with_uuids = context_client.SetService(updated_service)

        # PathComp requires endpoints, constraints and config rules
        updated_service_with_uuids = get_service_by_id(
            context_client, updated_service_id_with_uuids, rw_copy=True,
            include_config_rules=True, include_constraints=True, include_endpoint_ids=True)

        # Get active connection
        connections = context_client.ListConnections(updated_service_id_with_uuids)
        if len(connections.connections) == 0:
            MSG = 'Service({:s}) has no connections'
            str_service_id = grpc_message_to_json_string(updated_service_id_with_uuids)
            str_extra_details = MSG.format(str_service_id)
            raise NotImplementedException('service-with-no-connections', extra_details=str_extra_details)
        if len(connections.connections) > 1:
            MSG = 'Service({:s}) has multiple ({:d}) connections({:s})'
            str_service_id = grpc_message_to_json_string(updated_service_id_with_uuids)
            num_connections = len(connections.connections)
            str_connections = grpc_message_to_json_string(connections)
            str_extra_details = MSG.format(str_service_id, num_connections, str_connections)
            raise NotImplementedException('service-with-multiple-connections', extra_details=str_extra_details)

        old_connection = connections.connections[0]
        if len(old_connection.sub_service_ids) > 0:
            MSG = 'Service({:s})/Connection({:s}) has sub-services: {:s}'
            str_service_id = grpc_message_to_json_string(updated_service_id_with_uuids)
            str_connection_id = grpc_message_to_json_string(old_connection.connection_id)
            str_connection = grpc_message_to_json_string(old_connection)
            str_extra_details = MSG.format(str_service_id, str_connection_id, str_connection)
            raise NotImplementedException('service-connection-with-subservices', extra_details=str_extra_details)

        # Find alternative connections
        # pylint: disable=no-member
        pathcomp_request = PathCompRequest()
        pathcomp_request.services.append(updated_service_with_uuids)
        #pathcomp_request.k_disjoint_path.num_disjoint = 100
        pathcomp_request.k_shortest_path.k_inspection = 100
        pathcomp_request.k_shortest_path.k_return = 3

        LOGGER.debug('pathcomp_request={:s}'.format(grpc_message_to_json_string(pathcomp_request)))
        pathcomp = PathCompClient()
        pathcomp_reply = pathcomp.Compute(pathcomp_request)
        pathcomp.close()
        LOGGER.debug('pathcomp_reply={:s}'.format(grpc_message_to_json_string(pathcomp_reply)))

        if len(pathcomp_reply.services) == 0:
            MSG = 'KDisjointPath reported no services for Service({:s}): {:s}'
            str_service_id = grpc_message_to_json_string(updated_service_id_with_uuids)
            str_pathcomp_reply = grpc_message_to_json_string(pathcomp_reply)
            str_extra_details = MSG.format(str_service_id, str_pathcomp_reply)
            raise NotImplementedException('kdisjointpath-no-services', extra_details=str_extra_details)

        if len(pathcomp_reply.services) > 1:
            MSG = 'KDisjointPath reported subservices for Service({:s}): {:s}'
            str_service_id = grpc_message_to_json_string(updated_service_id_with_uuids)
            str_pathcomp_reply = grpc_message_to_json_string(pathcomp_reply)
            str_extra_details = MSG.format(str_service_id, str_pathcomp_reply)
            raise NotImplementedException('kdisjointpath-subservices', extra_details=str_extra_details)

        if len(pathcomp_reply.connections) == 0:
            MSG = 'KDisjointPath reported no connections for Service({:s}): {:s}'
            str_service_id = grpc_message_to_json_string(updated_service_id_with_uuids)
            str_pathcomp_reply = grpc_message_to_json_string(pathcomp_reply)
            str_extra_details = MSG.format(str_service_id, str_pathcomp_reply)
            raise NotImplementedException('kdisjointpath-no-connections', extra_details=str_extra_details)

        # compute a string representing the old connection
        str_old_connection = connection_to_string(old_connection)

        LOGGER.debug('old_connection={:s}'.format(grpc_message_to_json_string(old_connection)))

        candidate_new_connections = list()
        for candidate_new_connection in pathcomp_reply.connections:
            str_candidate_new_connection = connection_to_string(candidate_new_connection)
            if str_candidate_new_connection == str_old_connection: continue
            candidate_new_connections.append(candidate_new_connection)

        if len(candidate_new_connections) == 0:
            MSG = 'Unable to find a new suitable path: pathcomp_request={:s} pathcomp_reply={:s} old_connection={:s}'
            str_pathcomp_request = grpc_message_to_json_string(pathcomp_request)
            str_pathcomp_reply = grpc_message_to_json_string(pathcomp_reply)
            str_old_connection = grpc_message_to_json_string(old_connection)
            extra_details = MSG.format(str_pathcomp_request, str_pathcomp_reply, str_old_connection)
            raise OperationFailedException('no-new-path-found', extra_details=extra_details)
        
        str_candidate_new_connections = [
            grpc_message_to_json_string(candidate_new_connection)
            for candidate_new_connection in candidate_new_connections
        ]
        LOGGER.debug('candidate_new_connections={:s}'.format(str(str_candidate_new_connections)))

        new_connection = random.choice(candidate_new_connections)
        LOGGER.debug('new_connection={:s}'.format(grpc_message_to_json_string(new_connection)))

        # Change UUID of new connection to prevent collisions
        tmp_connection = Connection()
        tmp_connection.CopyFrom(new_connection)
        tmp_connection.connection_id.connection_uuid.uuid = str(uuid.uuid4())
        new_connection = tmp_connection

        # Feed TaskScheduler with the service to update, the old connection to
        # deconfigure and the new connection to configure. It will produce a
        # schedule of tasks (an ordered list of tasks to be executed) to
        # implement the requested changes.
        tasks_scheduler = TasksScheduler(self.service_handler_factory)
        tasks_scheduler.compose_service_connection_update(
            updated_service_with_uuids, old_connection, new_connection)
        tasks_scheduler.execute_all()

        return Empty()
