# encoding: utf-8
# This file is distributed under New Relic's license terms.
# See https://github.com/newrelic/rpm/blob/master/LICENSE for complete details.

require 'new_relic/agent/datastores'
require 'new_relic/agent/datastores/redis'

module NewRelic
  module Agent
    module Instrumentation
      module Redis
        extend self

        UNKNOWN = "unknown".freeze
        LOCALHOST = "localhost".freeze

        def host_for(client)
          client.path ? LOCALHOST : client.host
        rescue => e
          NewRelic::Agent.logger.debug "Failed to retrieve Redis host: #{e}"
          UNKNOWN
        end

        def port_path_or_id_for(client)
          client.path || client.port
        rescue => e
          NewRelic::Agent.logger.debug "Failed to retrieve Redis port_path_or_id: #{e}"
          UNKNOWN
        end
      end
    end
  end
end

DependencyDetection.defer do
  # Why not :redis? newrelic-redis used that name, so avoid conflicting
  named :redis_instrumentation

  depends_on do
    defined? ::Redis
  end

  depends_on do
    NewRelic::Agent.config[:disable_redis] == false
  end

  depends_on do
    NewRelic::Agent::Datastores::Redis.is_supported_version? &&
      NewRelic::Agent::Datastores::Redis.safe_from_third_party_gem?
  end

  executes do
    NewRelic::Agent.logger.info 'Installing Redis Instrumentation'

    Redis::Client.class_eval do
      alias_method :call_without_new_relic, :call

      def call(*args, &block)
        operation = args[0][0]
        statement = ::NewRelic::Agent::Datastores::Redis.format_command(args[0])

        hostname = NewRelic::Agent::Instrumentation::Redis.host_for(self)
        port_path_or_id = NewRelic::Agent::Instrumentation::Redis.port_path_or_id_for(self)

        segment = NewRelic::Agent::Transaction.start_datastore_segment(
          product: NewRelic::Agent::Datastores::Redis::PRODUCT_NAME,
          operation: operation,
          host: hostname,
          port_path_or_id: port_path_or_id,
          database_name: db
        )
        begin
          segment.notice_nosql_statement(statement) if statement
          call_without_new_relic(*args, &block)
        ensure
          segment.finish if segment
        end
      end

      alias_method :call_pipeline_without_new_relic, :call_pipeline

      def call_pipeline(*args, &block)
        pipeline = args[0]
        operation = pipeline.is_a?(::Redis::Pipeline::Multi) ? NewRelic::Agent::Datastores::Redis::MULTI_OPERATION : NewRelic::Agent::Datastores::Redis::PIPELINE_OPERATION
        statement = ::NewRelic::Agent::Datastores::Redis.format_pipeline_commands(pipeline.commands)

        hostname = NewRelic::Agent::Instrumentation::Redis.host_for(self)
        port_path_or_id = NewRelic::Agent::Instrumentation::Redis.port_path_or_id_for(self)

        segment = NewRelic::Agent::Transaction.start_datastore_segment(
          product: NewRelic::Agent::Datastores::Redis::PRODUCT_NAME,
          operation: operation,
          host: hostname,
          port_path_or_id: port_path_or_id,
          database_name: db
        )
        begin
          segment.notice_nosql_statement(statement)
          call_pipeline_without_new_relic(*args, &block)
        ensure
          segment.finish if segment
        end
      end

      alias_method :connect_without_new_relic, :connect

      def connect(*args, &block)
        hostname = NewRelic::Agent::Instrumentation::Redis.host_for(self)
        port_path_or_id = NewRelic::Agent::Instrumentation::Redis.port_path_or_id_for(self)

        segment = NewRelic::Agent::Transaction.start_datastore_segment(
          product: NewRelic::Agent::Datastores::Redis::PRODUCT_NAME,
          operation: NewRelic::Agent::Datastores::Redis::CONNECT,
          host: hostname,
          port_path_or_id: port_path_or_id,
          database_name: db
        )

        begin
          connect_without_new_relic(*args, &block)
        ensure
          segment.finish if segment
        end
      end
    end
  end
end