require 'mauve/sender'
require 'mauve/proto'
require 'mauve/mauve_thread'
require 'log4r'

module Mauve

  #
  # This class is responsible for sending a heartbeat to another mauve instance elsewhere.
  #
  class Heartbeat < MauveThread

    include Singleton

    #
    # Allow access to some basics.
    #
    attr_reader   :raise_after, :destination, :summary, :detail, :send_every

    #
    # This sets up the Heartbeat singleton
    #
    def initialize
      super

      @destination    = nil
      @summary        = "Mauve alert server heartbeat failed"
      @detail         = "The Mauve server at #{Server.instance.hostname} has failed to send a heartbeat."
      @raise_after    = 310
      @send_every     = 60
    end

    #
    # This is the time period after which an alert is raised by the remote Mauve instance.
    # @param [Integer] i Seconds
    # @return [Integer] Seconds
    def raise_after=(i)
      raise ArgumentError, "raise_after must be an integer" unless i.is_a?(Integer)      
      @raise_after = i
    end
    
    #
    # This is the time period after which an alert is raised by the remote Mauve instance.
    # @param [Integer] i Seconds
    # @return [Integer] Seconds
    def send_every=(i)
      raise ArgumentError, "send_every must be an integer" unless i.is_a?(Integer)      
      @send_every = i
    end

    alias poll_every= send_every= 

    # Sets the summary of the heartbeat
    #
    # @param [String] s Summary
    def summary=(s)
      raise ArgumentError, "summary must be a string" unless s.is_a?(String)
      @summary = s
    end

    # Sets the detail of the heartbeat
    #
    # @param [String] d Detail
    def detail=(d)
      raise ArgumentError, "detail must be a string" unless d.is_a?(String)
      @detail = d
    end

    # Sets the destinantion Mauve instance
    #
    # @param [String] d Destination
    #
    def destination=(d)
      raise ArgumentError, "destination must be a string" unless d.is_a?(String)
      @destination = d
    end

    # @return [Log4r::Logger]
    def logger
      @logger ||= Log4r::Logger.new(self.class.to_s)
    end

    private

    # @private This is the main heartbeat loop.
    def main_loop
      #
      # Don't send if no destination set.
      #
      return if @destination.nil?

      update = Mauve::Proto::AlertUpdate.new
      update.replace = false
      update.alert = []
      update.source = Server.instance.hostname
      update.transmission_id = rand(2**63)

      message = Mauve::Proto::Alert.new
      message.id = "mauve-heartbeat"
      message.summary = self.summary
      message.detail = self.detail
      message.raise_time = (Time.now.to_f+self.raise_after).to_i
      message.clear_time = Time.now.to_i

      update.alert << message

      begin
        Mauve::Sender.new(self.destination).send(update)
        logger.debug "Sent to #{self.destination}"
      rescue => e
        logger.error "Caught #{e.class}: #{e.message}"
        logger.debug e.backtrace.join("\n")
        raise
      end

      sleep @send_every
    end

  end

end