# -*- coding: utf-8 -*- #
# Copyright 2014 Google LLC. All Rights Reserved.
#
# 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.

"""Command for changing the default service of a URL map."""

from __future__ import absolute_import
from __future__ import division
from __future__ import unicode_literals

from apitools.base.py import encoding
from googlecloudsdk.api_lib.compute import base_classes
from googlecloudsdk.calliope import base
from googlecloudsdk.command_lib.compute import scope as compute_scope
from googlecloudsdk.command_lib.compute.backend_buckets import flags as backend_bucket_flags
from googlecloudsdk.command_lib.compute.backend_services import flags as backend_service_flags
from googlecloudsdk.command_lib.compute.url_maps import flags
from googlecloudsdk.command_lib.compute.url_maps import url_maps_utils
from googlecloudsdk.core import log


def _DetailedHelp():
  return {
      'brief': 'Change the default service or default bucket of a URL map.',
      'DESCRIPTION': """\
      *{command}* is used to change the default service or default
      bucket of a URL map. The default service or default bucket is
      used for any requests for which there is no mapping in the
      URL map.
      """,
  }


def _Args(parser):
  group = parser.add_mutually_exclusive_group(required=True)
  group.add_argument(
      '--default-service',
      help=(
          'A backend service that will be used for requests for which this '
          'URL map has no mappings.'
      ),
  )
  group.add_argument(
      '--default-backend-bucket',
      help=(
          'A backend bucket that will be used for requests for which this '
          'URL map has no mappings.'
      ),
  )


def _GetGetRequest(client, url_map_ref):
  """Returns the request for the existing URL map resource."""
  return (
      client.apitools_client.urlMaps,
      'Get',
      client.messages.ComputeUrlMapsGetRequest(
          urlMap=url_map_ref.Name(), project=url_map_ref.project
      ),
  )


def _GetSetRequest(client, url_map_ref, replacement):
  return (
      client.apitools_client.urlMaps,
      'Update',
      client.messages.ComputeUrlMapsUpdateRequest(
          urlMap=url_map_ref.Name(),
          urlMapResource=replacement,
          project=url_map_ref.project,
      ),
  )


def _Modify(
    resources,
    args,
    url_map,
    url_map_ref,
    backend_bucket_arg,
    backend_service_arg,
    supports_regional_backend_bucket=False,
):
  """Returns a modified URL map message."""
  replacement = encoding.CopyProtoMessage(url_map)

  if args.default_service:
    default_backend_uri = url_maps_utils.ResolveUrlMapDefaultService(
        args, backend_service_arg, url_map_ref, resources
    ).SelfLink()
  else:
    if supports_regional_backend_bucket:
      default_backend_uri = url_maps_utils.ResolveUrlMapDefaultBackendBucket(
          args, backend_bucket_arg, url_map_ref, resources
      ).SelfLink()
    else:
      default_backend_uri = backend_bucket_arg.ResolveAsResource(
          args, resources
      ).SelfLink()

  replacement.defaultService = default_backend_uri

  return replacement


def _GetRegionalGetRequest(client, url_map_ref):
  """Returns the request to get an existing regional URL map resource."""
  return (
      client.apitools_client.regionUrlMaps,
      'Get',
      client.messages.ComputeRegionUrlMapsGetRequest(
          urlMap=url_map_ref.Name(),
          project=url_map_ref.project,
          region=url_map_ref.region,
      ),
  )


def _GetRegionalSetRequest(client, url_map_ref, replacement):
  """Returns the request to update an existing regional URL map resource."""
  return (
      client.apitools_client.regionUrlMaps,
      'Update',
      client.messages.ComputeRegionUrlMapsUpdateRequest(
          urlMap=url_map_ref.Name(),
          urlMapResource=replacement,
          project=url_map_ref.project,
          region=url_map_ref.region,
      ),
  )


def _Run(
    args,
    holder,
    backend_bucket_arg,
    backend_service_arg,
    url_map_arg,
    supports_regional_backend_bucket=False,
):
  """Issues requests necessary to set the default service of URL maps."""
  client = holder.client

  url_map_ref = url_map_arg.ResolveAsResource(
      args, holder.resources, default_scope=compute_scope.ScopeEnum.GLOBAL
  )
  if url_maps_utils.IsRegionalUrlMapRef(url_map_ref):
    get_request = _GetRegionalGetRequest(client, url_map_ref)
  else:
    get_request = _GetGetRequest(client, url_map_ref)

  old_url_map = client.MakeRequests([get_request])

  modified_url_map = _Modify(
      holder.resources,
      args,
      old_url_map[0],
      url_map_ref,
      backend_bucket_arg,
      backend_service_arg,
      supports_regional_backend_bucket,
  )

  # If existing object is equal to the proposed object or if
  # _Modify() returns None, then there is no work to be done, so we
  # print the resource and return.
  if old_url_map[0] == modified_url_map:
    log.status.Print(
        'No change requested; skipping update for [{0}].'.format(
            old_url_map[0].name
        )
    )
    return old_url_map

  if url_maps_utils.IsRegionalUrlMapRef(url_map_ref):
    set_request = _GetRegionalSetRequest(client, url_map_ref, modified_url_map)
  else:
    set_request = _GetSetRequest(client, url_map_ref, modified_url_map)

  return client.MakeRequests([set_request])


@base.ReleaseTracks(base.ReleaseTrack.BETA, base.ReleaseTrack.GA)
@base.UniverseCompatible
class SetDefaultService(base.UpdateCommand):
  """Change the default service or default bucket of a URL map."""

  _supports_regional_backend_bucket = False
  detailed_help = _DetailedHelp()
  BACKEND_BUCKET_ARG = None
  BACKEND_SERVICE_ARG = None
  URL_MAP_ARG = None

  @classmethod
  def Args(cls, parser):
    if cls._supports_regional_backend_bucket:
      cls.BACKEND_BUCKET_ARG = (
          backend_bucket_flags.RegionSupportingBackendBucketArgumentForUrlMap(
              required=False
          )
      )
    else:
      cls.BACKEND_BUCKET_ARG = (
          backend_bucket_flags.BackendBucketArgumentForUrlMap(required=False)
      )
    cls.BACKEND_SERVICE_ARG = (
        backend_service_flags.BackendServiceArgumentForUrlMap(required=False)
    )
    cls.URL_MAP_ARG = flags.UrlMapArgument()
    cls.URL_MAP_ARG.AddArgument(parser)

    _Args(parser)

  def Run(self, args):
    holder = base_classes.ComputeApiHolder(self.ReleaseTrack())
    return _Run(
        args,
        holder,
        self.BACKEND_BUCKET_ARG,
        self.BACKEND_SERVICE_ARG,
        self.URL_MAP_ARG,
        self._supports_regional_backend_bucket,
    )


@base.ReleaseTracks(base.ReleaseTrack.ALPHA)
@base.UniverseCompatible
class SetDefaultServiceAlpha(SetDefaultService):
  """Change the default service or default bucket of a URL map."""

  _supports_regional_backend_bucket = True