require 'net/http'
require 'rexml/document'

module ActiveMessaging
  module Adapters
    module REST
    
      class Connection
        include ActiveMessaging::Adapter
        register :rest
        @@keep_alive = {"Connection" => "keep-alive", "Keep-Alive" => 300.to_s}
        
        def initialize(cfg)
          @user_agent = {"User-Agent" => self.class.to_s + " [a13g]"}
          @host = cfg.key?(:host) ? cfg[:host] : "127.0.0.1"
          @port = cfg.key?(:port) ? cfg[:port] : 8161.to_s
          @app = cfg.key?(:app) ? cfg[:app] : '/demo/amq'
        end
      
        def disconnect(headers = {})
        end
        
        def unsubscribe(name, headers = {})
        end        

        def received arg
        end
        
        def subscribe(name, headers = {})
          
          req = Net::HTTP::Post.new(@app, @user_agent)
          res = Net::HTTP.new(@host, @port).request(req, "destination=" + name + "&message=chat&type=listen")
          fields = res.get_fields('set-cookie')
          # assumes JSESSIONID from Servlet container, need be more defensive here
          @session_id = fields[0].split(';')[0].split('=')[1]
          puts "Subscribed to " + name.to_s + ", using session id of " + @session_id.to_s
          
        end
      
        def send destination, message, headers={}
          
          req = Net::HTTP::Post.new(@app, @user_agent.merge({"destination" => destination.to_s}))
          data = "message=<message type='chat' from='a13g'>" + message.to_s + "</message>&type=send"
          # needs error handling
          Net::HTTP.new(@host, @port).request(req, data)
          
        end

        def receive

          begin
            # needs better error handling
            req = Net::HTTP::Get.new(@app, @@keep_alive.merge(@user_agent.merge({"Cookie" => "JSESSIONID=" + @session_id.to_s})))
            res = Net::HTTP.new(@host, @port).request(req)
            parser = ResponseParser::new res.body
            return parser.messages.size == 0 ? nil : parser.messages[0]
          rescue
            puts $!
            raise $!
          end

        end

      end # ssalc

      class ResponseParser
        include REXML
       
        attr_reader :messages
        
        def initialize response
          @messages = []
          parse response
        end

        def parse response
          return if response.nil?
          _parse response
        end
        
        private
        def _parse response
          doc = Document.new(response)
          
          doc.root.elements.each do |e|
            # this needs to be more defensive
            headers = {"destination" => e.attributes['destination']}
            message = e.elements['message']
            @messages << Message.new(headers, message.text) unless message.nil?
          end
        end
        
      end

      class Message
        attr_accessor :headers, :body, :command
        
        def initialize headers, body, command='MESSAGE'
          @headers, @body, @command =  headers, body, command
        end
        
        def to_s
          "<REST::Message body='#{body}' headers='#{headers.inspect}' command='#{command}' >"
        end        
        
      end

    end
  end
end