class Google::Cloud::Env

def self.get
  ::Google::Cloud.env
end

def app_engine?
  variables["GAE_INSTANCE"] ? true : false
end

def app_engine_flexible?
  app_engine? && variables["GAE_ENV"] != "standard"
end

def app_engine_memory_mb
  result = variables["GAE_MEMORY_MB"]
  result&.to_i
end

def app_engine_service_id
  variables["GAE_SERVICE"]
end

def app_engine_service_version
  variables["GAE_VERSION"]
end

def app_engine_standard?
  app_engine? && variables["GAE_ENV"] == "standard"
end

def cloud_shell?
  variables["GOOGLE_CLOUD_SHELL"] ? true : false
end

def compute_engine?
  compute_smbios.google_compute?
end

def ensure_metadata timeout: nil
  compute_metadata.ensure_existence timeout: timeout
end

def initialize
  @variables = Variables.new
  @file_system = FileSystem.new
  @compute_smbios = ComputeSMBIOS.new
  @compute_metadata = ComputeMetadata.new variables: @variables,
                                          compute_smbios: @compute_smbios
end

def instance_attribute key
  compute_metadata.lookup "instance/attributes/#{key}"
rescue MetadataServerNotResponding
  nil
end

def instance_attribute_keys
  result = compute_metadata.lookup "instance/attributes/"
  result&.split
rescue MetadataServerNotResponding
  nil
end

def instance_description
  compute_metadata.lookup "instance/description"
rescue MetadataServerNotResponding
  nil
end

def instance_machine_type
  result = compute_metadata.lookup "instance/machine-type"
  result&.split("/")&.last
rescue MetadataServerNotResponding
  nil
end

def instance_name
  variables["GAE_INSTANCE"] || compute_metadata.lookup("instance/name")
rescue MetadataServerNotResponding
  nil
end

def instance_tags
  result = compute_metadata.lookup "instance/tags"
  result.nil? ? nil : JSON.parse(result)
rescue MetadataServerNotResponding
  nil
end

def instance_zone
  result = compute_metadata.lookup "instance/zone"
  result&.split("/")&.last
rescue MetadataServerNotResponding
  nil
end

def knative?
  variables["K_SERVICE"] ? true : false
end

def knative_service_id
  variables["K_SERVICE"]
end

def knative_service_revision
  variables["K_REVISION"]
end

def kubernetes_engine?
  kubernetes_engine_cluster_name ? true : false
end

def kubernetes_engine_cluster_name
  instance_attribute "cluster-name"
rescue MetadataServerNotResponding
  nil
end

def kubernetes_engine_namespace_id
  # The Kubernetes namespace is difficult to obtain without help from
  # the application using the Downward API. The environment variable
  # below is set in some older versions of GKE, and the file below is
  # present in Kubernetes as of version 1.9, but it is possible that
  # alternatives will need to be found in the future.
  variables["GKE_NAMESPACE_ID"] ||
    file_system.read("/var/run/secrets/kubernetes.io/serviceaccount/namespace")
end

def logging_agent_expected?
  compute_engine? && !cloud_shell? && (app_engine? || knative? || kubernetes_engine?)
end

def lookup_metadata type, entry, query: nil
  compute_metadata.lookup "#{type}/#{entry}", query: query
end

def lookup_metadata_response type, entry, query: nil
  compute_metadata.lookup_response "#{type}/#{entry}", query: query
end

def metadata?
  compute_metadata.check_existence == :confirmed
end

def numeric_project_id
  # CloudShell's metadata server seems to run in a dummy project.
  # We can get the user's normal project ID via environment variables,
  # but the numeric ID from the metadata service is not correct. So
  # disable this for CloudShell to avoid confusion.
  return nil if cloud_shell?
  result = begin
    compute_metadata.lookup "project/numeric-project-id"
  rescue MetadataServerNotResponding
    nil
  end
  result&.to_i
end

def project_id
  variables["GOOGLE_CLOUD_PROJECT"] ||
    variables["GCLOUD_PROJECT"] ||
    variables["DEVSHELL_PROJECT_ID"] ||
    compute_metadata.lookup("project/project-id")
rescue MetadataServerNotResponding
  nil
end

def raw_compute_engine?
  compute_engine? && !knative? && !app_engine? && !cloud_shell? && !kubernetes_engine?
end