# -*- 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 removing a host rule from 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.calliope import exceptions
from googlecloudsdk.command_lib.compute import scope as compute_scope
from googlecloudsdk.command_lib.compute.url_maps import flags
from googlecloudsdk.command_lib.compute.url_maps import url_maps_utils


def _DetailedHelp():
  return {
      'brief':
          'Remove a host rule from a URL map.',
      'DESCRIPTION': """
*{command}* is used to remove a host rule from a URL map. When
a host rule is removed, its path matcher is only removed if
it is not referenced by any other host rules and
`--delete-orphaned-path-matcher` is provided.
""",
      'EXAMPLES': """
To remove a host rule that contains the host `example.com`
from the URL map named `MY-URL-MAP`, you can use this
command:

  $ {command} MY-URL-MAP --host=example.com
"""
  }


def _GetGetRequest(client, url_map_ref):
  """Returns the request for the existing URL map resource."""
  if url_maps_utils.IsGlobalUrlMapRef(url_map_ref):
    return (client.apitools_client.urlMaps, 'Get',
            client.messages.ComputeUrlMapsGetRequest(
                urlMap=url_map_ref.Name(), project=url_map_ref.project))
  else:
    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 _GetSetRequest(client, url_map_ref, replacement):
  if url_maps_utils.IsGlobalUrlMapRef(url_map_ref):
    return (client.apitools_client.urlMaps, 'Update',
            client.messages.ComputeUrlMapsUpdateRequest(
                urlMap=url_map_ref.Name(),
                urlMapResource=replacement,
                project=url_map_ref.project))
  else:
    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 _Modify(args, existing):
  """Returns a modified URL map message."""
  replacement = encoding.CopyProtoMessage(existing)

  path_matcher_to_remove = None
  new_host_rules = []
  for host_rule in existing.hostRules:
    if args.host in host_rule.hosts:
      path_matcher_to_remove = host_rule.pathMatcher
    else:
      new_host_rules.append(host_rule)

  if not path_matcher_to_remove:
    raise exceptions.ToolException(
        'No host rule contains the host [{0}].'.format(args.host))

  replacement.hostRules = new_host_rules

  path_matcher_is_used_by_other_rules = False
  for host_rule in replacement.hostRules:
    if host_rule.pathMatcher == path_matcher_to_remove:
      path_matcher_is_used_by_other_rules = True
      break

  if not path_matcher_is_used_by_other_rules:
    if args.delete_orphaned_path_matcher:
      replacement.pathMatchers = [
          path_matcher for path_matcher in existing.pathMatchers
          if path_matcher.name != path_matcher_to_remove
      ]
    else:
      raise exceptions.ToolException(
          'This operation will orphan the path matcher [{0}]. To '
          'delete the orphan path matcher, rerun this command with '
          '[--delete-orphaned-path-matcher] or use [gcloud compute '
          'url-maps edit] to modify the URL map by hand.'.format(
              host_rule.pathMatcher))

  return replacement


def _Run(args, holder, url_map_arg):
  """Issues requests necessary to remove host rule on URL maps."""
  client = holder.client
  url_map_ref = url_map_arg.ResolveAsResource(
      args, holder.resources, default_scope=compute_scope.ScopeEnum.GLOBAL)
  get_request = _GetGetRequest(client, url_map_ref)

  objects = client.MakeRequests([get_request])
  new_object = _Modify(args, objects[0])
  return client.MakeRequests([_GetSetRequest(client, url_map_ref, new_object)])


@base.ReleaseTracks(base.ReleaseTrack.ALPHA, base.ReleaseTrack.BETA,
                    base.ReleaseTrack.GA)
class RemoveHostRule(base.UpdateCommand):
  """Remove a host rule from a URL map."""

  # TODO(b/144022508): Remove _include_l7_internal_load_balancing
  _include_l7_internal_load_balancing = True

  detailed_help = _DetailedHelp()
  URL_MAP_ARG = None

  @classmethod
  def Args(cls, parser):
    cls.URL_MAP_ARG = flags.UrlMapArgument(
        include_l7_internal_load_balancing=cls
        ._include_l7_internal_load_balancing)
    cls.URL_MAP_ARG.AddArgument(parser)
    parser.add_argument(
        '--host',
        required=True,
        help='One of the hosts in the host rule to remove.')
    parser.add_argument(
        '--delete-orphaned-path-matcher',
        action='store_true',
        default=False,
        help=('If provided and a path matcher is orphaned as a result of this '
              'command, the command removes the orphaned path matcher instead '
              'of failing.'))

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