# -*- 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.
"""Common classes and functions for images."""

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

from googlecloudsdk.api_lib.compute import constants
from googlecloudsdk.api_lib.compute import request_helper
from googlecloudsdk.api_lib.compute import utils
from googlecloudsdk.calliope import arg_parsers
from googlecloudsdk.core import log
from googlecloudsdk.core import properties
from googlecloudsdk.core.console import console_io
from googlecloudsdk.core.util import files as file_utils

FAMILY_PREFIX = 'family/'


class ImageExpander(object):
  """Class for expanding image aliases."""

  def __init__(self, compute_client, resources):
    """Instantiate ImageExpander and embed all required data into it.

    ImageExpander is a class depending on "base_classes"
    class layout (properties side-derived from one of base_class class). This
    function can be used to avoid unfeasible inheritance and use composition
    instead when refactoring away from base_classes into stateless style.

    This constructor embeds following properties into ImageExpander instance:
     - compute
     - messages
     - http
     - batch_url
     - resources

    Example:
      compute_holder = base_classes.ComputeApiHolder(self.ReleaseTrack())
      client = compute_holder.client
      resources = compute_holder.resources

      image_expander = ImageExpander(client, resources)
        or
      image_expander = ImageExpander(self.compute_client, self.resources)
        to use in a class derived from some of base_classes

      image_expander.ExpandImageFlag(...)

    Args:
      compute_client: compute_holder.client
      resources: compute_holder.resources
    """
    self._compute = compute_client.apitools_client
    self._messages = compute_client.messages
    self._http = compute_client.apitools_client.http
    self._batch_url = compute_client.batch_url
    self._resources = resources

  def GetMatchingImages(self, user_project, image, alias, errors):
    """Yields images from a public image project and the user's project."""
    service = self._compute.images
    requests = [
        (service,
         'List',
         self._messages.ComputeImagesListRequest(
             filter='name eq ^{0}(-.+)*-v.+'.format(alias.name_prefix),
             maxResults=constants.MAX_RESULTS_PER_PAGE,
             project=alias.project)),
        (service,
         'List',
         self._messages.ComputeImagesListRequest(
             filter='name eq ^{0}$'.format(image),
             maxResults=constants.MAX_RESULTS_PER_PAGE,
             project=user_project)),
    ]

    return request_helper.MakeRequests(
        requests=requests,
        http=self._http,
        batch_url=self._batch_url,
        errors=errors)

  def GetImage(self, image_ref):
    """Returns the image resource corresponding to the given reference."""
    errors = []
    requests = []
    name = image_ref.Name()
    if name.startswith(FAMILY_PREFIX):
      requests.append((self._compute.images,
                       'GetFromFamily',
                       self._messages.ComputeImagesGetFromFamilyRequest(
                           family=name[len(FAMILY_PREFIX):],
                           project=image_ref.project)))
    else:
      requests.append((self._compute.images,
                       'Get',
                       self._messages.ComputeImagesGetRequest(
                           image=name,
                           project=image_ref.project)))

    res = list(request_helper.MakeRequests(
        requests=requests,
        http=self._http,
        batch_url=self._batch_url,
        errors=errors))
    if errors:
      utils.RaiseException(
          errors,
          utils.ImageNotFoundError,
          error_message='Could not fetch image resource:')
    return res[0]

  def ExpandImageFlag(self,
                      user_project,
                      image=None,
                      image_family=None,
                      image_project=None,
                      return_image_resource=False,
                      confidential_vm=False,
                      image_family_scope=None,
                      support_image_family_scope=False):
    """Resolves the image or image-family value.

    If the value of image is one of the aliases defined in the
    constants module, both the user's project and the public image
    project for the alias are queried. Otherwise, only the user's
    project is queried. If image is an alias and image-project is
    provided, only the given project is queried.

    Args:
      user_project: The user's project.
      image: The name of the image.
      image_family: The family of the image. Is ignored if image name is
        specified.
      image_project: The project of the image.
      return_image_resource: If True, always makes an API call to also
        fetch the image resource.
      confidential_vm: If True, default image is different for confidential VMs
      image_family_scope: Override for selection of global or zonal image
        views.
      support_image_family_scope: If True, add support for the
        --image-family-scope flag.

    Returns:
      A tuple where the first element is the self link of the image. If
        return_image_resource is False, the second element is None, otherwise
        it is the image resource.
    """

    # If an image project was specified, then assume that image refers
    # to an image in that project.
    if image_project:
      image_project_ref = self._resources.Parse(
          image_project, collection='compute.projects')
      image_project = image_project_ref.Name()

    public_image_project = (image_project and image_project
                            in constants.PUBLIC_IMAGE_PROJECTS)

    image_ref = None
    collection = 'compute.images'
    project = image_project or properties.VALUES.core.project.GetOrFail
    params = {'project': project}

    if image:
      image_ref = self._resources.Parse(
          image,
          params=params,
          collection=collection)
    else:
      # Determine whether the 'global' or 'zonal' image view should be used.
      # image_family_scope will be set based on the flag or property, defaulting
      # to None if unset. If image_project is a public image and
      # image_family_scope is unset, it will be set to 'zonal'
      if support_image_family_scope:
        image_family_scope = (
            image_family_scope
            or properties.VALUES.compute.image_family_scope.Get())
        if not image_family_scope:
          image_family_scope = 'zonal' if public_image_project else None

      if image_family:
        if image_family_scope == 'zonal':
          params['zone'] = '-'
          collection = 'compute.imageFamilyViews'
      elif confidential_vm:
        image_family = constants.DEFAULT_IMAGE_FAMILY_FOR_CONFIDENTIAL_VMS
        params['project'] = 'ubuntu-os-cloud'
      else:
        image_family = constants.DEFAULT_IMAGE_FAMILY
        params['project'] = 'debian-cloud'
        if support_image_family_scope and image_family_scope != 'global':
          params['zone'] = '-'
          collection = 'compute.imageFamilyViews'

      image_ref = self._resources.Parse(
          image_family,
          params=params,
          collection=collection)

      if (hasattr(image_ref, 'image')
          and not image_ref.image.startswith(FAMILY_PREFIX)):
        relative_name = image_ref.RelativeName()
        relative_name = (relative_name[:-len(image_ref.image)] +
                         FAMILY_PREFIX + image_ref.image)
        image_ref = self._resources.ParseRelativeName(
            relative_name, image_ref.Collection())

    if image_project:
      return (image_ref.SelfLink(),
              self.GetImage(image_ref) if return_image_resource else None)

    alias = constants.IMAGE_ALIASES.get(image_ref.Name())

    # Check for hidden aliases.
    if not alias:
      alias = constants.HIDDEN_IMAGE_ALIASES.get(image_ref.Name())

    # If the image name given is not an alias and no image project was
    # provided, then assume that the image value refers to an image in
    # the user's project.
    if not alias:
      return (image_ref.SelfLink(),
              self.GetImage(image_ref) if return_image_resource else None)

    # At this point, the image is an alias and now we have to find the
    # latest one among the public image project and the user's
    # project.

    WarnAlias(alias)

    errors = []
    images = self.GetMatchingImages(user_project, image_ref.Name(), alias,
                                    errors)

    user_image = None
    public_images = []

    for image in images:
      if image.deprecated:
        continue
      image_ref2 = self._resources.Parse(
          image.selfLink, collection='compute.images', enforce_collection=True)
      if image_ref2.project == user_project:
        user_image = image
      else:
        public_images.append(image)

    if errors or not public_images:
      # This should happen only if there is something wrong with the
      # image project (e.g., operator error) or the global control
      # plane is down.
      utils.RaiseToolException(
          errors,
          'Failed to find image for alias [{0}] in public image project [{1}].'
          .format(image_ref.Name(), alias.project))

    def GetVersion(image):
      """Extracts the "20140718" from an image name like "debian-v20140718"."""
      parts = image.name.rsplit('v', 1)
      if len(parts) != 2:
        log.debug('Skipping image with malformed name [%s].', image.name)
        return ''
      return parts[1]

    public_candidate = max(public_images, key=GetVersion)
    if user_image:
      options = [user_image, public_candidate]

      idx = console_io.PromptChoice(
          options=[image.selfLink for image in options],
          default=0,
          message=('Found two possible choices for [--image] value [{0}].'
                   .format(image_ref.Name())))

      res = options[idx]

    else:
      res = public_candidate

    log.debug('Image resolved to [%s].', res.selfLink)
    return (res.selfLink, res if return_image_resource else None)


def HasWindowsLicense(resource, resource_parser):
  """Returns True if the given image or disk has a Windows license."""
  for license_uri in resource.licenses:
    license_ref = resource_parser.Parse(
        license_uri, collection='compute.licenses')
    if license_ref.project in constants.WINDOWS_IMAGE_PROJECTS:
      return True
  return False


def AddImageProjectFlag(parser):
  """Adds the --image flag to the given parser."""
  parser.add_argument(
      '--image-project',
      help="""\
      The Google Cloud project against which all image and
      image family references will be resolved. It is best practice to define
      image-project. A full list of available projects can be generated by
      running `gcloud projects list`.
          * If specifying one of our public images, image-project must be
            provided.
          * If there are several of the same image-family value in multiple
            projects, image-project must be specified to clarify the image to be
            used.
          * If not specified and either image or image-family is provided, the
            current default project is used.
        """)


def WarnAlias(alias):
  """WarnAlias outputs a warning telling users to not use the given alias."""
  msg = ('Image aliases are deprecated and will be removed in a future '
         'version. ')
  if alias.family is not None:
    msg += ('Please use --image-family={family} and --image-project={project} '
            'instead.').format(family=alias.family, project=alias.project)
  else:
    msg += 'Please use --image-family and --image-project instead.'

  log.warning(msg)


def AddGuestOsFeaturesArg(parser, messages):
  """Add the guest-os-features arg."""
  features_enum_type = messages.GuestOsFeature.TypeValueValuesEnum
  excluded_enums = [
      'FEATURE_TYPE_UNSPECIFIED',
      'SECURE_BOOT',  # Still exists in API but deprecated and has no effect.
  ]
  guest_os_features = sorted([
      e for e in features_enum_type.names() if e not in excluded_enums])

  if not guest_os_features:
    return
  parser.add_argument(
      '--guest-os-features',
      metavar='GUEST_OS_FEATURE',
      type=arg_parsers.ArgList(
          element_type=lambda x: x.upper(), choices=guest_os_features),
      help="""\
      This parameter enables one or more features for VM instances that use the
      image for their boot disks. See
      https://cloud.google.com/compute/docs/images/create-delete-deprecate-private-images#guest-os-features
      for descriptions of the supported features.""")


def AddImageFamilyScopeFlag(parser):
  """Add the image-family-scope flag."""
  parser.add_argument(
      '--image-family-scope',
      metavar='IMAGE_FAMILY_SCOPE',
      choices=['zonal', 'global'],
      help="""\
      Sets the scope for the `--image-family` flag. By default, when
      specifying an image family in a public image project, the zonal image
      family scope is used. All other projects default to the global
      image. Use this flag to override this behavior.""")


def GetFileContentAndFileType(file_path):
  """Helper function used for read file and determine file type."""
  file_content = file_utils.ReadBinaryFileContents(file_path)
  file_type = ''
  if file_path.endswith('.bin'):
    file_type = 'BIN'
  else:
    if not IsDERForm(file_content):
      raise utils.IncorrectX509FormError(
          'File is not in X509 binary DER form.')
    file_type = 'X509'
  return file_content, file_type


def IsDERForm(file_content):
  """Helper function that returns true if the file is X509 binary DER form."""
  # check the first two bytes to see if it matches the DER X509 hex signature
  return len(file_content) >= 2 and file_content[0:2] == b'\x30\x82'


def CreateFileContentBuffer(messages, file_path):
  """Helper function to read file and return FileContentBuffer."""
  file_content_buffer = messages.FileContentBuffer()
  content, file_type = GetFileContentAndFileType(file_path)
  file_content_buffer.content = content
  file_content_buffer.fileType =\
      messages.FileContentBuffer.FileTypeValueValuesEnum(file_type)
  return file_content_buffer


def CreateInitialStateConfig(args, messages):
  """Helper function used for creating InitialStateConfig."""
  initial_state_config = messages.InitialStateConfig()
  # check whether the initial_state_config's fields have been set
  has_set = False
  if args.platform_key_file:
    file_content_buffer = CreateFileContentBuffer(messages,
                                                  args.platform_key_file)
    initial_state_config.pk = file_content_buffer
    has_set = True
  key_exchange_key_file_paths = getattr(args, 'key_exchange_key_file', [])
  if key_exchange_key_file_paths:
    for file_path in key_exchange_key_file_paths:
      file_content_buffer = CreateFileContentBuffer(messages, file_path)
      initial_state_config.keks.append(file_content_buffer)
      has_set = True
  signature_database_file_paths = getattr(args, 'signature_database_file', [])
  if signature_database_file_paths:
    for file_path in signature_database_file_paths:
      file_content_buffer = CreateFileContentBuffer(messages, file_path)
      initial_state_config.dbs.append(file_content_buffer)
      has_set = True
  forbidden_signature_database_file_paths = getattr(args,
                                                    'forbidden_database_file',
                                                    [])
  if forbidden_signature_database_file_paths:
    for file_path in forbidden_signature_database_file_paths:
      file_content_buffer = CreateFileContentBuffer(messages, file_path)
      initial_state_config.dbxs.append(file_content_buffer)
      has_set = True
  return initial_state_config, has_set
