require 'rubygems'
require 'json'
require 'uuid'
require 'eventbus/common_init'
require 'eventbus/queue'

module EventBus
  
class Message
  
  attr_reader :data
  
  def initialize(application_id = EventBus.application_id)
    
    raise "No application ID specified!" if application_id.nil?
    
    @data = {
      'HEADER' => {
        'message_id' => UUID.new.generate.to_s,
        'message_type' => self.default_section_name,
        'status' => "BEGIN",
        'application_id' => application_id
      },
      'ERROR_INFO' => {
        'is_error' => false,
        'backtrace' => nil,
        'message' => nil
      },
      'PAYLOAD' => {}
    }
    
    @connection_driver = ENV["EVENTBUS_CONNECTOR"] || "Stomp"
    
    driver_module = "#{@connection_driver}ConnectionDriver"
    
    require_relative "connectors/#{@connection_driver.downcase}"
    
    # Eh, pretty much just swiped from ActiveSupport "constantize"..
    conn_module = Object.const_defined?(driver_module) ? Object.const_get(driver_module) : Object.const_missing(driver_module)
    
    extend conn_module 
    
    connection_driver_initialize
    
  end
  
  
  def set(key, val, opts = {})
    
    # This is for convenience and to make messages more 
    # human-readable by eliminating the !Binary encoding 
    # in YAML messages. I'm not willing to make this method
    # more expensive by walking deep structures to do the
    # same legwork, because this isn't a functionality issue. 
    # The message deserializes just fine without this.
    # If your YAML is popping up with random !binary segments
    # in the YAML *and this bothers you*, just do 
    # a force_encoding("UTF-8") on the members of the structure
    # as needed.
    if val.is_a?(String)
      val = val.dup if val.frozen? # Copy to non-frozen string. 
      val.force_encoding("UTF-8")
    end

    raise "You must specify a key name!" if key.nil?
    section = opts.delete(:section) || self.default_section_name
    
    @data['PAYLOAD'][section.to_s] = {} if @data['PAYLOAD'][section.to_s].nil?
    @data['PAYLOAD'][section.to_s][key.to_s] = val
  end
  
  def get(key, opts = {})
    raise "You must specify a key name!" if key.nil?
    section = opts.delete(:section) || self.default_section_name
    
    return @data['PAYLOAD'][section.to_s].nil? ? nil : @data['PAYLOAD'][section.to_s][key.to_s]
  end
  
  # opts: 
  # :queue_name -- the base queue name to receive the message. Defaults to "dispatcher"
  # :global_queue -- Do not prepend the application ID and do not append the environment
  # :system_queue -- Do not prepend the application ID to the queue_name
  #
  # Normally a queue name is calculated to be: applicationid.queue_name.environment
  # so that eventbus can handle multiple applications on the same eventbus instance, and 
  # multiple environment-scoped eventbuses on the same broker. By applying :global_queue
  # or :system_queue, you are breaking that scoping to some degree. Maybe that's what you want,
  # but be careful or you might get cross-talk between applications or environments!
  def send(opts = {})
    
    queue_name = opts.delete(:queue_name)
    
    if queue_name.nil?
      queue_name = "dispatcher"
      opts[:system_queue] = true
    end
    
    opts[:queue_name] = Queue.calc_name(queue_name, application_id, ENV['EVENTBUS_PROD_LEVEL'], opts)
      
    puts "Sending message to: #{opts[:queue_name]}"
    
    set_special(:HEADER, :sender, $0)
    send_raw self.dump, opts
  end

  def set_error(exception)
    
    exception.backtrace.map { |frame| frame.force_encoding("UTF-8") }
    exception.message.force_encoding("UTF-8")
    
    @data['ERROR_INFO']['backtrace'] = exception.backtrace
    @data['ERROR_INFO']['message']   = exception.message
    self.is_error = true
    self.status = exception.class.name
  end

  def dump
    JSON.generate(@data, :indent => ' ', :space => ' ', :object_nl => "\n", :array_nl => "\n", :max_nesting => 50)
  end
  
  def load(raw)
    @data = JSON::parse(raw)
  end
  
  def application_id
    return get_special(:HEADER, :application_id)
  end
  
  def message_id
    return get_special(:HEADER, :message_id)
  end
  
  def message_type
    return get_special(:HEADER, :message_type)
  end
  
  def message_type=(val)
    set_special(:HEADER, :message_type, val)
  end
  
  def status
    return get_special(:HEADER, :status)
  end
  
  def status=(val)
    set_special(:HEADER, :status, val)
  end
  
  def error_message
    get_special(:ERROR_INFO, :message)
  end
  
  def error_message=(val)
    set_special(:ERROR_INFO, :message, val)
  end
  
  def is_error
    get_special(:ERROR_INFO, :is_error)
  end
  
  def is_error=(val)
    set_special(:ERROR_INFO, :is_error, val)
  end
  
  def backtrace
    return get_special(:ERROR_INFO, :backtrace)
  end
  
  def backtrace=(val)
    set_special(:ERROR_INFO, :backtrace, val)
  end
  
  def clear_error_info
    self.is_error = false
    self.backtrace = []
    self.error_message = nil
  end
  
  def default_section_name
    return self.class.name.split(/::/).last
  end
  
  private
  
  def set_special(block, key, val)
    if val.is_a?(String)
      val = val.dup if val.frozen? # Copy to non-frozen string. 
      val.force_encoding("UTF-8")
    end
    @data[block.to_s][key.to_s] = val
  end

  def get_special(block, key)
    return @data[block.to_s][key.to_s]
  end

end

end # module EventBus