# Copyright (c) 2021 Contrast Security, Inc. See https://www.contrastsecurity.com/enduser-terms-0317a for more details.
# frozen_string_literal: true

require 'contrast/utils/string_utils'

module Contrast
  module Api
    module Decorators
      # Used to decorate the {Contrast::Api::Dtm::TraceEvent} protobuf model to
      # convert our {Contrast::Agent::AssessContrastEvent} to the dtm.
      module TraceEvent
        def self.included klass
          klass.extend(ClassMethods)
        end

        # The TeamServer uses the Event's type and action to render it in the Details page. These values control the
        # left-hand "What happened" column and the data shown in the right-hand data
        #
        # @param contrast_event [Contrast::Agent::Assess::ContrastEvent]
        # @return [Contrast::Api::Dtm::TraceEvent]
        def build_display_params! contrast_event
          self.type = contrast_event.policy_node.node_type
          self.action = contrast_event.policy_node.build_action
          self
        end

        # The TeamServer uses the Event's representation of the data to render the actual data used in the dataflow on
        # the Details page.
        #
        # @param contrast_event [Contrast::Agent::Assess::ContrastEvent]
        # @return [Contrast::Api::Dtm::TraceEvent]
        def build_dataflow! contrast_event
          # Figure out what the target of this event was. This can't be pulled into the decorator because SourceEvent
          # has a custom impl :/
          taint_target = contrast_event.determine_taint_target(self)
          truncate_obj = Contrast::Utils::ObjectShare::OBJECT_KEY != taint_target
          self.object = Contrast::Api::Dtm::TraceEventObject.build(contrast_event.object, truncate_obj)
          truncate_ret = Contrast::Utils::ObjectShare::RETURN_KEY != taint_target
          self.ret = Contrast::Api::Dtm::TraceEventObject.build(contrast_event.ret, truncate_ret)
          build_event_args!(contrast_event, taint_target)
          build_taint_ranges!(contrast_event)
          self
        end

        # Wrapper around build_event_object for the args array. Handles
        # tainting the correct argument.
        # @return [Contrast::Api::Dtm::TraceEvent]
        def build_event_args! contrast_event, taint_target
          contrast_event.args.each_index do |idx|
            truncate_arg = taint_target != idx
            event_arg = Contrast::Api::Dtm::TraceEventObject.build(contrast_event.args[idx], truncate_arg)
            args << event_arg
          end
          self
        end

        # TeamServer only supports one object's taint ranges at a time. We keep
        # those tags on the event directly, so we just need to convert them to
        # their DTM form in order to report this.
        #
        # @param contrast_event [Contrast::Agent::AssessContrastEvent]
        # @return [Contrast::Api::Dtm::TraceEvent]
        def build_taint_ranges! contrast_event
          # If there's no taint_target, this isn't a dataflow trace, but a
          # trigger one
          return self unless contrast_event&.tags

          self.taint_ranges += Contrast::Api::Dtm::TraceTaintRange.build_for_event(contrast_event.tags)
          self
        end

        # For each Parent in the ContrastEvent, capture its id and report it to TeamServer.
        #
        # @param contrast_event [Contrast::Agent::AssessContrastEvent]
        # @return [Contrast::Api::Dtm::TraceEvent]
        def build_parent_ids! contrast_event
          contrast_event&.parent_events&.each do |event|
            next unless event

            parent = Contrast::Api::Dtm::ParentObjectId.new
            parent.id = event.event_id.to_i
            parent_object_ids << parent
          end
          self
        end

        # Convert the caller into the Stack DTM TeamServer consumes
        #
        # @param contrast_event [Contrast::Agent::AssessContrastEvent]
        # @return [Contrast::Api::Dtm::TraceEvent]
        def build_stack! contrast_event
          # We delayed doing this as long as possible b/c it's expensive
          stack_dtms = Contrast::Utils::StackTraceUtils.build_assess_stack_array(contrast_event.stack_trace)
          self.stack += stack_dtms
          self
        end

        # Class methods for TraceEvent
        module ClassMethods
          def build contrast_event
            event_dtm = new
            event_dtm.build_display_params!(contrast_event)
            event_dtm.build_dataflow!(contrast_event)
            event_dtm.build_stack!(contrast_event)
            event_dtm.timestamp_ms = contrast_event.time.to_i
            event_dtm.thread = Contrast::Utils::StringUtils.force_utf8(contrast_event.thread)
            event_dtm.build_parent_ids!(contrast_event)
            event_dtm.object_id = contrast_event.event_id.to_i
            event_dtm.signature = Contrast::Api::Dtm::TraceEventSignature.build(contrast_event.ret,
                                                                                contrast_event.policy_node,
                                                                                contrast_event.args)
            event_dtm
          end
        end
      end
    end
  end
end

Contrast::Api::Dtm::TraceEvent.include(Contrast::Api::Decorators::TraceEvent)