begin
  require "newrelic_rpm"
rescue LoadError
  raise LoadError,
        'Gem newrelic_rpm is required for logging to New Relic. Please add the gem "newrelic_rpm" to your Gemfile.'
end

# Send log messages to NewRelic
#
# The :error and :fatal log entries will show up under
# "Applications" > "Application Name" > "Events" > "Errors" in New Relic.
#
# Example:
#   SemanticLogger.add_appender(appender: :new_relic)
module SemanticLogger
  module Appender
    class NewRelic < SemanticLogger::Subscriber
      # Create Appender
      #
      # Parameters
      #   level: [:trace | :debug | :info | :warn | :error | :fatal]
      #     Override the log level for this appender.
      #     Default: :error
      #
      #   formatter: [Object|Proc]
      #     An instance of a class that implements #call, or a Proc to be used to format
      #     the output from this appender
      #     Default: Use the built-in formatter (See: #call)
      #
      #   filter: [Regexp|Proc]
      #     RegExp: Only include log messages where the class name matches the supplied.
      #     regular expression. All other messages will be ignored.
      #     Proc: Only include log messages where the supplied Proc returns true
      #           The Proc must return true or false.
      def initialize(level: :error, **args, &block)
        super
      end

      # Returns [Hash] of parameters to send to New Relic.
      def call(log, logger)
        h = SemanticLogger::Formatters::Raw.new.call(log, logger)
        h.delete(:time)
        h.delete(:exception)
        {metric: log.metric, custom_params: h}
      end

      # Send an error notification to New Relic
      def log(log)
        # Send error messages as Runtime exceptions
        exception =
          if log.exception
            log.exception
          else
            error = RuntimeError.new(log.message)
            error.set_backtrace(log.backtrace) if log.backtrace
            error
          end
        # For more documentation on the NewRelic::Agent.notice_error method see:
        # http://rubydoc.info/github/newrelic/rpm/NewRelic/Agent#notice_error-instance_method
        # and https://docs.newrelic.com/docs/ruby/ruby-agent-api
        ::NewRelic::Agent.notice_error(exception, formatter.call(log, self))
        true
      end
    end
  end
end