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

require 'contrast/components/logger'
require 'contrast/agent/telemetry/exception/event'

module Contrast
  module Agent
    module Telemetry
      # This is the Telemetry::Hash, which will store Contrast::Agent::Telemetry::Exception::Event, so we can push
      # freely, without worrying about validating the event before that. Telemetry::Hash has a max size of events,
      # default is 10 events
      class Hash < Hash
        include Contrast::Components::Logger::InstanceMethods
        HASH_SIZE_LIMIT = 10

        # Wrapper to set a value in this Telemetry::Hash only if the provided value is of the data_type for this
        # Telemetry::Hash or the hash has not reached its limit of for unique keys
        #
        # @param key [Object] the key to which to associate the value
        # @param value [Object] the value to store
        # @return [Object, nil] echo back out the value as the Hash#[]= method does, or nil if not of the expected
        #   data_type
        def []= key, value
          # 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 exception_limit?
          # If the given value is of unexpected type, do not add it to avoid issues later where type is assumed.
          return unless valid_value?(value)

          super(key, value)
        end

        # Increment the occurrences for the exception object contained in this Telemetry::Hash
        #
        # @param key [Object] the key to check for the exception stored in this Telemetry::Hash
        def increment key
          value = self[key]
          return unless value&.exceptions&.any?

          value.exceptions[0].increment_occurrences
        end

        # Determine if hash has reached exception event limit
        # @return [Boolean]
        def exception_limit?
          unless size < HASH_SIZE_LIMIT
            logger.debug("Number of TelemetryExceptions exceeds limit of #{ HASH_SIZE_LIMIT }")
            return true
          end
          false
        end

        private

        # Determine if the given value is valid based on the datatype which this Telemetry::Hash contains
        # @param value [Object]
        # @return boolean
        def valid_value? value
          unless value.cs__is_a?(Contrast::Agent::Telemetry::Exception::Event)
            logger.debug('The following key will be omitted', value: value)
            return false
          end

          true
        end
      end
    end
  end
end