# This file is distributed under New Relic's license terms.
# See https://github.com/newrelic/newrelic-ruby-agent/blob/main/LICENSE for complete details.
# frozen_string_literal: true

require 'new_relic/agent/http_clients/uri_util'

module NewRelic
  module Agent
    class Transaction
      class RequestAttributes
        # the HTTP standard has "referrer" mispelled as "referer"
        attr_reader :accept, :content_length, :content_type, :host, :other_headers, :port, :referer, :request_method,
          :request_path, :user_agent

        HTTP_ACCEPT_HEADER_KEY = 'HTTP_ACCEPT'.freeze

        BASE_HEADERS = %w[CONTENT_LENGTH CONTENT_TYPE HTTP_ACCEPT HTTP_REFERER HTTP_USER_AGENT PATH_INFO REMOTE_HOST
          REQUEST_METHOD REQUEST_URI SERVER_PORT].freeze

        ATTRIBUTE_PREFIX = 'request.headers.'

        def initialize(request)
          @request_path = path_from_request(request)
          @referer = referer_from_request(request)
          @accept = attribute_from_env(request, HTTP_ACCEPT_HEADER_KEY)
          @content_length = content_length_from_request(request)
          @content_type = attribute_from_request(request, :content_type)
          @host = attribute_from_request(request, :host)
          @port = port_from_request(request)
          @user_agent = attribute_from_request(request, :user_agent)
          @request_method = attribute_from_request(request, :request_method)
          @other_headers = other_headers_from_request(request)
        end

        def assign_agent_attributes(txn)
          default_destinations = AttributeFilter::DST_TRANSACTION_TRACER |
            AttributeFilter::DST_TRANSACTION_EVENTS |
            AttributeFilter::DST_ERROR_COLLECTOR

          if referer
            destinations = allow_other_headers? ? default_destinations : AttributeFilter::DST_ERROR_COLLECTOR
            txn.add_agent_attribute(:'request.headers.referer', referer, destinations)
          end

          if request_path
            destinations = if allow_other_headers?
              default_destinations
            else
              AttributeFilter::DST_TRANSACTION_TRACER | AttributeFilter::DST_ERROR_COLLECTOR
            end
            txn.add_agent_attribute(:'request.uri', request_path, destinations)
          end

          if accept
            txn.add_agent_attribute(:'request.headers.accept', accept, default_destinations)
          end

          if content_length
            txn.add_agent_attribute(:'request.headers.contentLength', content_length, default_destinations)
          end

          if content_type
            txn.add_agent_attribute(:'request.headers.contentType', content_type, default_destinations)
          end

          if host
            txn.add_agent_attribute(:'request.headers.host', host, default_destinations)
          end

          if user_agent
            txn.add_agent_attribute(:'request.headers.userAgent', user_agent, default_destinations)
          end

          if request_method
            txn.add_agent_attribute(:'request.method', request_method, default_destinations)
          end

          if port && allow_other_headers?
            txn.add_agent_attribute(:'request.headers.port', port, default_destinations)
          end

          other_headers.each do |header, value|
            txn.add_agent_attribute(header, value, default_destinations)
          end
        end

        private

        # Make a safe attempt to get the referer from a request object, generally successful when
        # it's a Rack request.

        def referer_from_request(request)
          if referer = attribute_from_request(request, :referer)
            HTTPClients::URIUtil.strip_query_string(referer.to_s)
          end
        end

        # In practice we expect req to be a Rack::Request or ActionController::AbstractRequest
        # (for older Rails versions).  But anything that responds to path can be passed to
        # perform_action_with_newrelic_trace.
        #
        # We don't expect the path to include a query string, however older test helpers for
        # rails construct the PATH_INFO enviroment variable improperly and we're generally
        # being defensive.

        ROOT_PATH = '/'.freeze

        def path_from_request(request)
          path = attribute_from_request(request, :path) || ''
          path = HTTPClients::URIUtil.strip_query_string(path)
          path.empty? ? ROOT_PATH : path
        end

        def content_length_from_request(request)
          if content_length = attribute_from_request(request, :content_length)
            content_length.to_i
          end
        end

        def port_from_request(request)
          if port = attribute_from_request(request, :port)
            port.to_i
          end
        end

        def attribute_from_request(request, attribute_method)
          if request.respond_to?(attribute_method)
            request.send(attribute_method)
          end
        end

        def attribute_from_env(request, key)
          if env = attribute_from_request(request, :env)
            env[key]
          end
        end

        def allow_other_headers?
          NewRelic::Agent.config[:allow_all_headers] && !NewRelic::Agent.config[:high_security]
        end

        def other_headers_from_request(request)
          # confirm that `request` is an instance of `Rack::Request` by checking
          # for #each_header
          return NewRelic::EMPTY_HASH unless allow_other_headers? && request.respond_to?(:each_header)

          request.each_header.with_object({}) do |(header, value), hash|
            next if BASE_HEADERS.include?(header)

            hash[formatted_header(header)] = value
          end
        end

        def formatted_header(raw_name)
          "#{ATTRIBUTE_PREFIX}#{NewRelic::LanguageSupport.camelize_with_first_letter_downcased(raw_name)}".to_sym
        end
      end
    end
  end
end