# frozen_string_literal: true

module Gitlab
  module Database
    module BackgroundMigration
      module HealthStatus
        module Signals
          # Base class for a signal
          class Base
            attr_reader :indicator_class, :reason

            def initialize(indicator_class, reason:)
              @indicator_class = indicator_class
              @reason = reason
            end

            def to_s
              "#{short_name} (indicator: #{indicator_class}; reason: #{reason})"
            end

            # :nocov:
            def log_info?
              false
            end

            def stop?
              false
            end
            # :nocov:

            private

            def short_name
              self.class.name.demodulize
            end
          end

          # A Signals::Stop is an indication to put a migration on hold or stop it entirely:
          # In general, we want to slow down or pause the migration.
          class Stop < Base
            # :nocov:
            def log_info?
              true
            end

            def stop?
              true
            end
            # :nocov:
          end

          # A Signals::Normal indicates normal system state: We carry on with the migration
          # and may even attempt to optimize its throughput etc.
          class Normal < Base; end

          # When given an Signals::Unknown, something unexpected happened while
          # we evaluated system indicators.
          class Unknown < Base
            # :nocov:
            def log_info?
              true
            end
            # :nocov:
          end

          # No signal could be determined, e.g. because the indicator
          # was disabled.
          class NotAvailable < Base; end
        end
      end
    end
  end
end