# frozen_string_literal: true
require 'json'
require 'base64'
require 'open3'
require 'krane/kubectl'

module Krane
  class EjsonSecretError < FatalDeploymentError
    def initialize(msg)
      super("Generation of Kubernetes secrets from ejson failed: #{msg}")
    end
  end

  class EjsonSecretProvisioner
    EJSON_SECRET_ANNOTATION = "kubernetes-deploy.shopify.io/ejson-secret"
    EJSON_SECRET_KEY = "kubernetes_secrets"
    EJSON_SECRETS_FILE = "secrets.ejson"
    EJSON_KEYS_SECRET = "ejson-keys"
    delegate :namespace, :context, :logger, to: :@task_config

    def initialize(task_config:, ejson_keys_secret:, ejson_file:, statsd_tags:, selector: nil)
      @ejson_keys_secret = ejson_keys_secret
      @ejson_file = ejson_file
      @statsd_tags = statsd_tags
      @selector = selector
      @task_config = task_config
      @kubectl = Kubectl.new(
        task_config: @task_config,
        log_failure_by_default: false,
        output_is_sensitive_default: true # output may contain ejson secrets
      )
    end

    def resources
      @resources ||= build_secrets
    end

    private

    def build_secrets
      unless @ejson_keys_secret
        raise EjsonSecretError, "Secret #{EJSON_KEYS_SECRET} not provided, cannot decrypt secrets"
      end
      return [] unless File.exist?(@ejson_file)
      with_decrypted_ejson do |decrypted|
        secrets = decrypted[EJSON_SECRET_KEY]
        unless secrets.present?
          logger.warn("#{EJSON_SECRETS_FILE} does not have key #{EJSON_SECRET_KEY}."\
            "No secrets will be created.")
          return []
        end

        secrets.map do |secret_name, secret_spec|
          validate_secret_spec(secret_name, secret_spec)
          resource = generate_secret_resource(secret_name, secret_spec["_type"], secret_spec["data"])
          resource.validate_definition(@kubectl)
          if resource.validation_failed?
            raise EjsonSecretError, "Resulting resource Secret/#{secret_name} failed validation"
          end
          resource
        end
      end
    end

    def encrypted_ejson
      @encrypted_ejson ||= load_ejson_from_file
    end

    def public_key
      encrypted_ejson["_public_key"]
    end

    def private_key
      @private_key ||= fetch_private_key_from_secret
    end

    def validate_secret_spec(secret_name, spec)
      errors = []
      errors << "secret type unspecified" if spec["_type"].blank?
      errors << "no data provided" if spec["data"].blank?

      unless errors.empty?
        raise EjsonSecretError, "Ejson incomplete for secret #{secret_name}: #{errors.join(', ')}"
      end
    end

    def generate_secret_resource(secret_name, secret_type, data)
      unless data.is_a?(Hash) && data.values.all? { |v| v.is_a?(String) } # Secret data is map[string]string
        raise EjsonSecretError, "Data for secret #{secret_name} was invalid. Only key-value pairs are permitted."
      end
      encoded_data = data.each_with_object({}) do |(key, value), encoded|
        # Leading underscores in ejson keys are used to skip encryption of the associated value
        # To support this ejson feature, we need to exclude these leading underscores from the secret's keys
        secret_key = key.sub(/\A_/, '')
        encoded[secret_key] = Base64.strict_encode64(value)
      end

      labels = { "name" => secret_name }
      labels.reverse_merge!(@selector.to_h) if @selector

      secret = {
        'kind' => 'Secret',
        'apiVersion' => 'v1',
        'type' => secret_type,
        'metadata' => {
          "name" => secret_name,
          "labels" => labels,
          "namespace" => namespace,
          "annotations" => { EJSON_SECRET_ANNOTATION => "true" },
        },
        "data" => encoded_data,
      }

      Krane::Secret.build(
        namespace: namespace, context: context, logger: logger, definition: secret, statsd_tags: @statsd_tags,
      )
    end

    def load_ejson_from_file
      return {} unless File.exist?(@ejson_file)
      JSON.parse(File.read(@ejson_file))
    end

    def with_decrypted_ejson
      return unless File.exist?(@ejson_file)

      Dir.mktmpdir("ejson_keydir") do |key_dir|
        File.write(File.join(key_dir, public_key), private_key)
        decrypted = decrypt_ejson(key_dir)
        yield decrypted
      end
    end

    def decrypt_ejson(key_dir)
      # ejson seems to dump both errors and output to STDOUT
      out_err, st = Open3.capture2e("EJSON_KEYDIR=#{key_dir} ejson decrypt #{@ejson_file}")
      raise EjsonSecretError, out_err unless st.success?
      JSON.parse(out_err)
    rescue JSON::ParserError
      raise EjsonSecretError, "Failed to parse decrypted ejson"
    end

    def fetch_private_key_from_secret
      encoded_private_key = @ejson_keys_secret["data"][public_key]
      unless encoded_private_key
        raise EjsonSecretError, "Private key for #{public_key} not found in #{EJSON_KEYS_SECRET} secret"
      end

      Base64.decode64(encoded_private_key)
    rescue Kubectl::ResourceNotFoundError
      raise EjsonSecretError, "Secret/#{EJSON_KEYS_SECRET} is required to decrypt EJSON and could not be found"
    end
  end
end