# Copyright 2014 Google Inc. 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 creating target pools."""

from __future__ import absolute_import
from __future__ import unicode_literals
from googlecloudsdk.api_lib.compute import base_classes
from googlecloudsdk.calliope import base
from googlecloudsdk.calliope import exceptions as calliope_exceptions
from googlecloudsdk.command_lib.compute import flags as compute_flags
from googlecloudsdk.command_lib.compute.backend_services import (
    flags as backend_services_flags)
from googlecloudsdk.command_lib.compute.http_health_checks import (
    flags as http_health_check_flags)
from googlecloudsdk.command_lib.compute.target_pools import flags
from googlecloudsdk.core import log


class Create(base.CreateCommand):
  """Define a load-balanced pool of virtual machine instances.

  *{command}* is used to create a target pool. A target pool resource
  defines a group of instances that can receive incoming traffic
  from forwarding rules. When a forwarding rule directs traffic to a
  target pool, Google Compute Engine picks an instance from the
  target pool based on a hash of the source and
  destination IP addresses and ports. For more
  information on load balancing, see
  [](https://cloud.google.com/compute/docs/load-balancing-and-autoscaling/)

  To add instances to a target pool, use 'gcloud compute
  target-pools add-instances'.
  """

  BACKUP_POOL_ARG = None
  HTTP_HEALTH_CHECK_ARG = None
  TARGET_POOL_ARG = None

  @classmethod
  def Args(cls, parser):
    parser.display_info.AddFormat(flags.DEFAULT_LIST_FORMAT)
    cls.BACKUP_POOL_ARG = flags.BackupPoolArgument(required=False)
    cls.HTTP_HEALTH_CHECK_ARG = (
        http_health_check_flags.HttpHealthCheckArgumentForTargetPoolCreate(
            required=False))
    cls.HTTP_HEALTH_CHECK_ARG.AddArgument(parser)
    cls.TARGET_POOL_ARG = flags.TargetPoolArgument()
    cls.TARGET_POOL_ARG.AddArgument(parser, operation_type='create')
    parser.display_info.AddCacheUpdater(flags.TargetPoolsCompleter)

    parser.add_argument(
        '--backup-pool',
        help="""\
        Together with ``--failover-ratio'', this flag defines the fallback
        behavior of the target pool (primary pool) to be created by this
        command. If the ratio of the healthy instances in the primary pool
        is at or below the specified ``--failover-ratio value'', then traffic
        arriving at the load-balanced IP address will be directed to the
        backup pool. If this flag is provided, then ``--failover-ratio'' is
        required.
        """)

    parser.add_argument(
        '--description',
        help='An optional description of this target pool.')

    parser.add_argument(
        '--failover-ratio',
        type=float,
        help="""\
        Together with ``--backup-pool'', defines the fallback behavior of the
        target pool (primary pool) to be created by this command. If the
        ratio of the healthy instances in the primary pool is at or below this
        number, traffic arriving at the load-balanced IP address will be
        directed to the backup pool. For example, if 0.4 is chosen as the
        failover ratio, then traffic will fail over to the backup pool if
        more than 40% of the instances become unhealthy.
        If not set, the traffic will be directed the
        instances in this pool in the ``force'' mode, where traffic will be
        spread to the healthy instances with the best effort, or to all
        instances when no instance is healthy.
        If this flag is provided, then ``--backup-pool'' is required.
        """)

    parser.add_argument(
        '--health-check',
        metavar='HEALTH_CHECK',
        help="""\
        DEPRECATED, use --http-health-check.
        Specifies an HTTP health check resource to use to determine the health
        of instances in this pool. If no health check is specified, traffic will
        be sent to all instances in this target pool as if the instances
        were healthy, but the health status of this pool will appear as
        unhealthy as a warning that this target pool does not have a health
        check.
        """)

    backend_services_flags.AddSessionAffinity(parser, target_pools=True)

  def Run(self, args):
    """Issues requests necessary for adding a target pool."""
    holder = base_classes.ComputeApiHolder(self.ReleaseTrack())
    client = holder.client

    if ((args.backup_pool and not args.IsSpecified('failover_ratio')) or
        (args.failover_ratio and not args.IsSpecified('backup_pool'))):
      raise calliope_exceptions.ToolException(
          'Either both or neither of [--failover-ratio] and [--backup-pool] '
          'must be provided.')

    if args.failover_ratio is not None:
      if args.failover_ratio < 0 or args.failover_ratio > 1:
        raise calliope_exceptions.ToolException(
            '[--failover-ratio] must be a number between 0 and 1, inclusive.')

    if args.health_check:
      args.http_health_check = args.health_check
      log.warning('The --health-check flag is deprecated. Use equivalent '
                  '--http-health-check=%s flag.', args.health_check)

    if args.http_health_check:
      http_health_check = [self.HTTP_HEALTH_CHECK_ARG.ResolveAsResource(
          args, holder.resources).SelfLink()]

    else:
      http_health_check = []

    target_pool_ref = self.TARGET_POOL_ARG.ResolveAsResource(
        args,
        holder.resources,
        scope_lister=compute_flags.GetDefaultScopeLister(client))

    if args.backup_pool:
      args.backup_pool_region = target_pool_ref.region
      backup_pool_uri = self.BACKUP_POOL_ARG.ResolveAsResource(
          args, holder.resources).SelfLink()
    else:
      backup_pool_uri = None

    request = client.messages.ComputeTargetPoolsInsertRequest(
        targetPool=client.messages.TargetPool(
            backupPool=backup_pool_uri,
            description=args.description,
            failoverRatio=args.failover_ratio,
            healthChecks=http_health_check,
            name=target_pool_ref.Name(),
            sessionAffinity=(
                client.messages.TargetPool.SessionAffinityValueValuesEnum(
                    args.session_affinity))),
        region=target_pool_ref.region,
        project=target_pool_ref.project)

    return client.MakeRequests([(client.apitools_client.targetPools, 'Insert',
                                 request)])
