require "time"
require "socket"

module PlainApm
  module EventAttributes
    SOURCES_WITH_EXTRA_ATTRIBUTES = %w[
      action_controller
      action_mailer
      active_job
      deploy
      exception
    ].freeze

    # FIXME: This is duplicated for ErrorReporter
    IGNORED_EXCEPTIONS = [
      "Sidekiq::JobRetry::Skip", # Sidekiq uses exceptions for control flow.
      "ActionController::RoutingError" # Rails unmapped route, raised before the request hits the app.
    ].freeze

    def attributes_from_deploy(tool, revision)
      source = "deploy"

      attrs = {
        "source" => source,
        "revision" => revision,
        "name" => tool
      }

      attrs.merge!(trace_attributes(source))

      [tool, attrs]
    end

    def attributes_from_exception(e, context, error_source)
      source = "exception"

      return [source, nil] if IGNORED_EXCEPTIONS.include?(e.class.name)

      attrs = {
        "class" => e.class.name,
        "message" => e.message,
        "backtrace" => e.backtrace
      }

      if error_source
        attrs["event_source"] = error_source
      end

      if context[:env]
        attrs["params"] = context[:env]["action_dispatch.request.parameters"]
      end

      if context[:job]&.is_a?(ActiveJob::Base)
        attrs["job_class"] = context[:job].class.name
        attrs["queue_name"] = context[:job].queue_name
      end

      if e.cause
        attrs.merge!({
          "cause_class" => e.cause.class.name,
          "cause_message" => e.cause.message,
          "cause_backtrace" => e.cause.backtrace
        })
      end

      attrs.merge!(trace_attributes(source))

      [source, attrs]
    end

    def attributes_from_notification(event)
      name, source = *event.name.split(".")
      loc = source_location

      attrs = {
        "source" => source,
        "name" => name,
        "allocations" => event.allocations,
        "event_time" => event.time,
        "duration" => event.duration
      }

      attrs["thread_allocations"] = event.thread_allocations if event.respond_to?(:thread_allocations)
      attrs["source_location"] = loc if !loc.nil?

      attrs.merge!(trace_attributes(source))

      [name, attrs]
    end

    private

    def trace_attributes(source)
      process_attributes.merge(context_attributes)
    end

    def process_attributes
      {
        "thread_id" => Thread.current.object_id,
        "collected_at" => Time.now.iso8601(9),
        "version" => PlainApm::VERSION
      }.merge(
        host_attributes
      )
    end

    def host_attributes
      @host_attributes ||= {
        "hostname" => Socket.gethostname,
        "pid" => Process.pid
      }
    end

    def context_attributes
      ##
      # Context contains the trace ID (which comes from either
      # HTTP_X_REQUEST_ID header, the deserialized job,
      # or is generated by the trace_id middleware).
      # It can also carry user inserted app data.
      if defined?(PlainApm::Extensions::Context)
        PlainApm::Extensions::Context.current.transform_keys(&:to_s)
      else
        {}
      end
    end

    def source_location
      filtered_backtrace&.first
    end

    def filtered_backtrace
      if defined?(Rails) && defined?(Rails::BacktraceCleaner)
        @cleaner ||= Rails::BacktraceCleaner.new
        @cleaner.clean(caller)
      end
    end
  end
end