# encoding: utf-8
require 'one_apm/collector/support/shell_poller'
require 'one_apm/collector/support/proc_poller'
require 'one_apm/collector/support/jruby_poller'

module OneApm
  module Collector
    class SamplerCollection
      include Enumerable

      def initialize(event_listener)
        @samplers = []
        @event_listener = event_listener
        @event_listener.subscribe(:before_harvest) { poll_samplers }
      end

      def each(&blk)
        @samplers.each(&blk)
      end

      def clear()
        @samplers.clear
      end

      def sampler_class_registered?(sampler_class)
        self.any? { |s| s.class == sampler_class }
      end

      def load_samplers
        Sampler.sampler_classes.each do |subclass|
          add_sampler(subclass)
        end
      end

      def poll_samplers
        @samplers.delete_if do |sampler|
          begin
            sampler.poll
            false
          rescue => e
            OneApm::Manager.logger.warn("Removing #{sampler} from list", e)
            true
          end
        end
      end

      def add_sampler(sampler_class)
        supported = sampler_class.supported_on_this_platform?
        enabled   = sampler_class.enabled?
        if supported && enabled && !sampler_class_registered?(sampler_class)
          sampler = sampler_class.new
          sampler.setup_events(@event_listener) if sampler.respond_to?(:setup_events)
          sampler.set_poller(poller)            if sampler.respond_to?(:set_poller)
          @samplers << sampler
          OneApm::Manager.logger.debug("Registered #{sampler_class.name} for harvest time sampling.")
        else
          OneApm::Manager.logger.debug("#{sampler_class.name} not supported on this platform.")
        end
      rescue OneApm::Collector::Sampler::Unsupported => e
        OneApm::Manager.logger.info("#{sampler_class.name} not available: #{e}")
      rescue => e
        OneApm::Manager.logger.error("Error registering sampler:", e)
      end

      def poller 
        @pller ||= begin
          if OneApm::Collector::JrubyPoller.enable?
            OneApm::Collector::JrubyPoller.new 
          elsif OneApm::Collector::ProcPoller.enable?
            OneApm::Collector::ProcPoller.new 
          else
            OneApm::Collector::ShellPoller.new  
          end 
        end
      end

    end
  end
end