# encoding: utf-8

require 'one_apm/support/parameter_filtering'

module OneApm
  module Agent
    module Instrumentation
      module Grape
        extend self

        API_ENDPOINT   = 'api.endpoint'.freeze
        FORMAT_REGEX   = /\(\/?\.(:format|json)?\)/.freeze
        VERSION_REGEX  = /:version(\/|$)/.freeze
        EMPTY_STRING   = ''.freeze
        MIN_VERSION    = VersionNumber.new('0.2.0')

        def handle_transaction(endpoint, class_name)
          return unless endpoint && route = endpoint.route
          name_transaction(route, class_name)
          capture_params(endpoint) if OneApm::Manager.config[:capture_params]
        end

        def name_transaction(route, class_name)
          txn_name = name_for_transaction(route, class_name)
          segment_name = "Middleware/Grape/#{class_name}/call"
          Transaction.set_default_transaction_name(txn_name, :grape, segment_name)
        end

        def name_for_transaction(route, class_name)
          route_path, route_method, route_version = path_method_version_of(route)
          action_name = route_path.sub(FORMAT_REGEX, EMPTY_STRING)
          method_name = route_method

          if route_version
            action_name = action_name.sub(VERSION_REGEX, EMPTY_STRING)
            "#{class_name}-#{route_version}#{action_name} (#{method_name})"
          else
            "#{class_name}#{action_name} (#{method_name})"
          end
        end
        
        if defined?(::Grape::VERSION) && VersionNumber.new(::Grape::VERSION) >= VersionNumber.new('0.16.0')
          def path_method_version_of(route)
            [route.path, route.request_method, route.version]
          end    
        else
          def path_method_version_of(route)
            [route.route_path, route.route_method, route.route_version]
          end
        end

        def capture_params(endpoint)
          txn = Transaction.tl_current
          env = endpoint.request.env
          params = OneApm::Support::ParameterFiltering::apply_filters(env, endpoint.params)
          params.delete("route_info")
          txn.filtered_params = params
        end
      end
    end
  end
end

LibraryDetection.defer do
  # Why not just :grape? oneapm-grape used that name already, and while we're
  # not shipping yet, overloading the name interferes with the plugin.
  named :grape

  depends_on do
    OneApm::Manager.config[:disable_grape] == false
  end

  depends_on do
    defined?(::Grape::VERSION) &&
      ::OneApm::VersionNumber.new(::Grape::VERSION) >= ::OneApm::Agent::Instrumentation::Grape::MIN_VERSION
  end

  executes do
    OneApm::Manager.logger.info 'Installing Grape instrumentation'
    instrument_call
  end

  def instrument_call
    ::Grape::API.class_eval do
      def call_with_one_apm(env)
        begin
          response = call_without_one_apm(env)
        ensure
          begin
            endpoint = env[::OneApm::Agent::Instrumentation::Grape::API_ENDPOINT]
            ::OneApm::Agent::Instrumentation::Grape.handle_transaction(endpoint, self.class.name)
          rescue => e
            OneApm::Manager.logger.warn("Error in Grape instrumentation", e)
          end
        end

        response
      end

      alias_method :call_without_one_apm, :call
      alias_method :call, :call_with_one_apm
    end
  end

end