# This module is primarily intended for use with ActiveMQ, though 
# it should work with any Stomp-speaking broker. 
require 'eventbus/common_init'
require_relative 'stomp/slogger'
require 'socket'
require 'stomp'
module StompConnectionDriver

  @@StompConnector_Connection = nil

  def connection_driver_initialize
    
  end 

  def get_connection
  
    opts = {
      :hosts => [
        {
          :host => ENV["BROKER_HOST"] || "localhost",
          :port => ENV["BROKER_PORT"] || (ENV['EVENTBUS_STOMP_SSL'] == "false" ? 61613 : 61614),
          :login => ENV["BROKER_USER"] || "eventbus",
          :passcode => ENV["BROKER_PASS"] || "eventbus",
          :ssl => ENV['EVENTBUS_STOMP_SSL'] == "false" ? false : true  # True unless specified in ENV
      }
      ],
      :reliable => ENV['EVENTBUS_STOMP_RELIABLE'] == "false" ? false : true,  # True unless specified in ENV
      :initial_reconnect_delay => 1,
      :max_reconnect_delay => 10,
      :use_exponential_back_off => true,
      :back_off_multiplier => 2,
      :closed_check => ENV['EVENTBUS_STOMP_CLOSED_CHECK'] == "false" ? false : true,
      :hbser => true,
      :max_hbread_fails => ENV['EVENTBUS_STOMP_MAX_HBREAD_FAILS'] || 5,
      :max_hbrlck_fails => ENV['EVENTBUS_STOMP_MAX_HBREADLOCK_FAILS'] || 5,
      :connect_timeout => 30,
      :connect_headers => {
        
        # :host
        #
        # This is the STOMP VHOST, NOT a hostname! Make sure your broker is set up right!
        # This is a requirement of STOMP 1.2. The broker may (read: probably will) 
        # drop connections on you if you're sending a value it doesn't recognize. If you're
        # getting lots of "connection reset by peer" and connection drops, dude, look at this really hard.
        # Behavior highly dependent on the broker, however. Works fine in Apache Apollo by adding this line 
        # to the apollo.xml file:
        # 
        #    <host_name>eventbus</host_name>
        #
        
        :host => ENV['BROKER_VHOST'] || "eventbus",
        
        # :accept-version and :heart-beat
        #
        # Used to set up heart-beating to keep connection alive and notice right away when it isn't.
        # 
        # Value is two integer millisecond interval values, comma-delimited
        # <interval we can send>,<interval we want to receive from server>
        # Heart-beating can be disabled entirely or from one end by using 0 for 
        # one or both of these values in the EVENTBUS_STOMP_HEARTBEAT_INTERVALS environment variable:
        # 0,0     Disable all heart-beating
        # 0,1000  Receive heart-beats from broker every 1000ms, but don't send them.
        # 1000,0  Send heart-beats from client every 1000ms, but don't look for them from broker.
        #
        # This is turned on by default to keep the connection alive in some environments where they can be 
        # dropped silently. If the heart-beat fails, it will trigger the :reliable re-connect. 
        # Best to leave it on.
        #
        # For heart-beats to work properly, you must be using Stomp protocol version 1.2 or higher.
        # Tested to work with Apache Apollo. 
        
        :"accept-version" => ENV['EVENTBUS_STOMP_PROTOCOL_VERSION'] || "1.2",
        :"heart-beat" => ENV['EVENTBUS_STOMP_HEARTBEAT_INTERVALS'] || '1000,1000',  
      },
      :logger => ENV['EVENTBUS_STOMP_DETAILED_LOGGING'] == "true" ? EventBus::Connectors::Stomp::Slogger.new : nil,
    }
  
    # If we never opened one, or if it's closed and not reliable, then open a new connection.
    if @@StompConnector_Connection.nil? || (@@StompConnector_Connection.closed? && ! @@StompConnector_Connction.reliable?)
      EventBus.logger.info("Connecting to STOMP with options: #{opts.to_s}")
      @@StompConnector_Connection = Stomp::Client.new(opts)
    end
    
    # I'm  not sure whether we should sleep here if the connection is closed?() but is reliable?()
    # Assuming that the connection will do the right thing and punting until I find out different.
    
    return @@StompConnector_Connection
  
  end

  # opts basically just gets passed to the Stomp client.send, so it can be things
  # like :persistent => false, etc. :persistent is true by default.
  def send_raw(content, opts = {})
    
    queue_name = opts.delete(:queue_name)
    queue_name = "/queue/#{queue_name}"
    
    opts[:persistent] = true if opts[:persistent].nil?

    # "Fix" an ActiveMQ "bug" where it assumes that any message with a content-length
    # header is a bytes-message instead of a text message. This behavior prevents the
    # message conent from showing up in the "Message Details" section when you try
    # to view the message in ActiveMQ's admin interface. 
    #
    # Note that the *correct* behavior is the opposite of this: All Stomp messages
    # are recommended to include content-length. However, this is the *less annoying*
    # and *more useful* behavior. 
    opts[:suppress_content_length] = true if opts[:suppress_content_length].nil?
    
    EventBus.logger.info "Stomp sending message to: #{queue_name}"
    
    client = get_connection
    client.publish(queue_name, content, opts)
    
  end
  
  def watch_queue(listen_queue)
    client = get_connection
    
    queue_name = listen_queue.match('^/') ? listen_queue : "/queue/#{listen_queue}"
    
    # OK, so some assumption that we're using ActiveMQ here. We'll work that out eventually. The point
    # is, though, that we want to allow for maximum parallelism -- not just by thread but also across 
    # processes and machines. Therefore, don't lock the queue exclusively (i.e. don't kill other clients!)
    # and only take blocks of one message rather than claiming large blocks. These assumptions should become
    # configurable at some point, but for now it's not really a concern.

    client.subscribe(queue_name, {"activemq.prefetchSize" => 1, "activemq.exclusive" => false}) do |msg|
      yield msg.body
    end
    
    
  end
      
end