# frozen_string_literal: true

module Floe
  class ContainerRunner
    module DockerMixin
      def image_name(image)
        image.match(%r{^(?<repository>.+/)?(?<image>.+):(?<tag>.+)$})&.named_captures&.dig("image")
      end

      # 63 is the max kubernetes pod name length
      # -5 for the "floe-" prefix
      # -9 for the random hex suffix and leading hyphen
      MAX_CONTAINER_NAME_SIZE = 63 - 5 - 9

      def container_name(image)
        name = image_name(image)
        raise ArgumentError, "Invalid docker image [#{image}]" if name.nil?

        # Normalize the image name to be used in the container name.
        # This follows RFC 1123 Label names in Kubernetes as they are the most restrictive
        # See https://kubernetes.io/docs/concepts/overview/working-with-objects/names/#dns-label-names
        # and https://github.com/kubernetes/kubernetes/blob/952a9cb0/staging/src/k8s.io/apimachinery/pkg/util/validation/validation.go#L178-L184
        #
        # This does not follow the leading and trailing character restriction because we will embed it
        # below with a prefix and suffix that already conform to the RFC.
        normalized_name = name.downcase.gsub(/[^a-z0-9-]/, "-")[0, MAX_CONTAINER_NAME_SIZE]
        # Ensure that the normalized_name doesn't end in any invalid characters after we
        # limited the length to the MAX_CONTAINER_NAME_SIZE.
        normalized_name.gsub!(/[^a-z0-9]+$/, "")

        "floe-#{normalized_name}-#{SecureRandom.hex(4)}"
      end
    end
  end
end