# Copyright (c) 2023 Contrast Security, Inc. See https://www.contrastsecurity.com/enduser-terms-0317a for more details.
# frozen_string_literal: true

require 'contrast/agent/telemetry/input_analysis_cache_event'

module Contrast
  module Agent
    module Telemetry
      # This hash will store the telemetry data for the Protect InputAnalysis cache.
      class CacheHash < Hash
        include Contrast::Components::Logger::InstanceMethods
        # Set per request:
        HASH_SIZE_LIMIT = 100

        # Wrapper to set a value in this Telemetry::Hash only if the provided value is of the data_type for this
        # Telemetry::CacheHash or the hash has not reached its limit for unique keys.
        # Saves Array of reportable events.
        #
        # @param key [Object] the key to which to associate the value
        # @param events [array<Object>]
        # @return [Object, nil] echo back out the value as the Hash#[]= method does, or nil if not of the expected
        #   data_type
        def []= key, events
          # If telemetry is not running, do not add more as we want to avoid a memory leak.
          return unless Contrast::Agent.telemetry_queue&.running?
          # If the Hash is full, do not add more as we want to avoid consuming all application resources.
          return if at_limit?
          # If the given value is of unexpected type, do not add it to avoid issues later where type is assumed.
          return unless valid_event?(events)

          super(key, events)
        end

        # Determine if hash has reached exception event limit.
        #
        # @return [Boolean]
        def at_limit?
          unless length < HASH_SIZE_LIMIT
            logger.debug("[Telemetry] Number of IA cache events exceeds limit of #{ HASH_SIZE_LIMIT }")
            return true
          end
          false
        end

        private

        # Checks to see if the given object is a valid event.
        # @param event [Contrast::Agent::Telemetry::InputAnalysisCacheEvent]
        def valid_event? events
          events&.all?(Contrast::Agent::Telemetry::InputAnalysisCacheEvent)
        end
      end
    end
  end
end