require 'monitor'
require 'flydata-core/logger'

module Flydata
  module Helper
    # Take care of action ownership management
    # - Receive a request from both scheduler and worker.
    # - Give a action with ownership to workers
    class ActionOwnershipChannel
      include MonitorMixin
      include FlydataCore::Logger

      def initialize
        @action_ownership_map = ActionOwnership.action_ownership_map
        @queue = {}
        super
      end

      # Called from schdeduler and worker
      # action_name must be symbol
      def request_action(action_name, action_info = {})
        action_ownership = @action_ownership_map[action_name]
        if action_ownership.nil?
          # unknown action.  probably a new action
          log_warn "unsupported action `#{action_name}'.  Skip."
          return false
        end
        self.synchronize do
          if @queue.has_key?(action_name)
            false
          else
            @queue[action_name] =
                      {
                        action_ownership: action_ownership,
                        action_info: action_info
                      }
            true
          end
        end
      end

      # Called from worker only
      def take_action_ownership(new_owner)
        self.synchronize do
          return nil if @queue.empty?

          # Wait until action will be processed
          action = @queue.values.first
          action_ownership = action[:action_ownership]
          return nil if action_ownership.processing?

          # Check resource change flag
          if action_ownership.resource_change &&
            @action_ownership_map.any? { |name, act_own|
              (act_own.resource_change && act_own.processing?) }
            return nil
          end

          @queue.shift  # delete last acion from queue
          action_ownership.owner = new_owner
          action
        end
      end

      # Called from worker only
      def return_action_ownership(action_ownership)
        self.synchronize do
          action_ownership.owner = nil
          action_ownership.last_processed_time = Time.now.to_f
        end
      end

      # For debug
      def queue
        @queue.dup
      end

      def map
        @action_ownership_map.dup
      end

      def dump
        $logger.debug "\n" + <<EOT
========
action_ownership_channel dump

queue:
#{@queue}

action_ownership_map:
#{@action_ownership_map}
========
EOT
      end
    end
  end
end