require 'eventmachine'
require 'msgpack'

module Ganymed
  module Client

    ##
    # An EventMachine Protocol that can send events to a Ganymed processor.
    #
    module Processor
      include EM::Deferrable

      # Emit a new Event.
      #
      # @param [String] ns  Event namespace.
      # @param [Object] value  Event value.
      # @param [Hash] opts  Options
      # @option opts [String] cf  Consolidation function used in this event.
      # @option opts [Time] now  Event timestamp.
      # @option opts [Fixnum] resolution  Event resolution.
      # @option opts [String] origin  Event origin.
      def event(ns, value, opts={})
        opts = {
          :cf => nil,
          :now => Time.now.utc,
          :resolution => 0,
          :origin => @origin,
        }.merge(opts)

        data = {
          :_type => :event,
          :n => ns,
          :c => opts[:cf],
          :o => opts[:origin],
          :t => opts[:now].to_i,
          :r => opts[:resolution].to_i,
          :v => value
        }

        send_data(data.to_msgpack)
      end

      # Emit a metadata object to the Processor.
      #
      # A metadata object contains arbitrary data related to the origin. This
      # can be queried by Websocket clients for displaying information about
      # origins.
      #
      # @param [Hash] data  Metadata object.
      # @param [Hash] opts  Options
      # @option opts [String] origin  Metadata origin.
      def metadata(data, opts={})
        opts = {
          :origin => @origin,
        }.merge(opts)

        data = {
          :_type => :metadata,
          :origin => opts[:origin],
          :data => data,
        }

        send_data(data.to_msgpack)
      end

      # Connect to a Ganymed processor.
      #
      # @param [String] host  Host to connect to.
      # @param [Fixnum] port  Port to connect to.
      # @param [String] origin Origin of events. Defaults to the
      #                        fully-qualified hostname.
      def self.connect(host, port, origin=nil)
        EM.connect(host, port, self, host, port, origin)
      end

      # @private
      def initialize(host, port, origin=nil)
        @host, @port = host, port
        @origin = origin || ::Socket.gethostbyname(::Socket.gethostname).first
      end

      # @private
      def connection_completed
        @reconnecting = false
        @connected = true
        succeed
      end

      # @private
      def unbind
        if @connected or @reconnecting
          EM.add_timer(1) { reconnect(@host, @port) }
          @connected = false
          @reconnecting = true
          @deferred_status = nil
        else
          raise "unable to connect #{@origin} to ganymed processor at #{@host}:#{@port}"
        end
      end
    end
  end
end