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

require 'contrast/agent/reporting/input_analysis/input_type'
require 'contrast/agent/reporting/input_analysis/score_level'
require 'contrast/agent/reporting/details/bot_blocker_details'
require 'contrast/agent/protect/rule/input_classification/base'
require 'contrast/utils/object_share'

module Contrast
  module Agent
    module Protect
      module Rule
        # This module will do the Input Classification stage of CMD Injection rule
        # as a result input would be marked as WORTHWATCHING or IGNORE,
        # to be analyzed at the sink level.
        module BotBlockerInputClassification
          USER_AGENT = 'USER_AGENT'
          AGENT_LIB_HEADER_NAME = 'user-agent'
          BOT_BLOCKER_MATCH = 'bot-blocker-input-tracing-v1'

          class << self
            include Contrast::Agent::Protect::Rule::InputClassification::Base

            private

            # This methods checks if input is tagged WORTHWATCHING or IGNORE matches value with it's
            # key if needed and Creates new instance of InputAnalysisResult.
            #
            # @param request [Contrast::Agent::Request] the current request context.
            # @param rule_id [String] The name of the Protect Rule.
            # @param input_type [Contrast::Agent::Reporting::InputType] The type of the user input.
            # @param value [String, Array<String>] the value of the input.
            #
            # @return res [Contrast::Agent::Reporting::InputAnalysisResult, nil]
            def create_new_input_result request, rule_id, input_type, value
              return unless request.headers.key(value) == USER_AGENT

              super(request, rule_id, input_type, value)
            end

            # Creates new instance of AgentLib evaluation result with direct call to AgentLib.
            #
            # @param rule_id [String] The name of the Protect Rule.
            # @param _input_type [Contrast::Agent::Reporting::InputType] The type of the user input.
            # @param value [String, Array<String>] the value of the input.
            def build_input_eval rule_id, _input_type, value
              Contrast::AGENT_LIB.eval_header(AGENT_LIB_HEADER_NAME,
                                              value,
                                              Contrast::AGENT_LIB.rule_set[rule_id],
                                              Contrast::AGENT_LIB.eval_option[:NONE])
            end

            # Creates specific result from the AgentLib evaluation.
            #
            # @param rule_id [String] The name of the Protect Rule.
            # @param input_type [Contrast::Agent::Reporting::InputType] The type of the user input.
            # @param value [String, Array<String>] the value of the input.
            # @param request [Contrast::Agent::Request] the current request context.
            # @param input_eval [Contrast::AgentLib::EvalResult] the result of the input evaluation.
            def build_ia_result rule_id, input_type, value, request, input_eval
              ia_result = new_ia_result(rule_id, input_type, request.path, value)
              score = input_eval&.score || 0
              if score >= THRESHOLD
                ia_result.score_level = DEFINITEATTACK
                ia_result.ids << BOT_BLOCKER_MATCH
                ia_result.details = Contrast::Agent::Reporting::Details::BotBlockerDetails.new
                # details:
                add_details(ia_result, value)
              else
                ia_result.score_level = IGNORE
              end
              ia_result
            end

            def add_details ia_result, value
              ia_result.details.bot = value.downcase
              if value.include?(Contrast::Utils::ObjectShare::CARROT)
                ia_result.details.bot.delete!(Contrast::Utils::ObjectShare::CARROT)
              end
              ia_result.details.user_agent = value
            end
          end
        end
      end
    end
  end
end