module Grape
  class Request < Rack::Request
    HTTP_PREFIX = 'HTTP_'.freeze

    alias rack_params params

    def initialize(env, options = {})
      extend options[:build_params_with] || Grape::Extensions::ActiveSupport::HashWithIndifferentAccess::ParamBuilder
      super(env)
    end

    def params
      @params ||= build_params
    end

    def headers
      @headers ||= build_headers
    end

    private

    def grape_routing_args
      args = env[Grape::Env::GRAPE_ROUTING_ARGS].dup
      # preserve version from query string parameters
      args.delete(:version)
      args.delete(:route_info)
      args
    end

    def build_headers
      headers = {}
      env.each_pair do |k, v|
        next unless k.to_s.start_with? HTTP_PREFIX

        k = k[5..-1].split('_').each(&:capitalize!).join('-')
        headers[k] = v
      end
      headers
    end
  end
end