module ActiveMessaging
  VERSION  = "0.6.1"
  APP_ROOT = ENV['APP_ROOT'] || ENV['RAILS_ROOT'] || ((defined? RAILS_ROOT) && RAILS_ROOT) || File.dirname($0)
  APP_ENV  = ENV['APP_ENV']  || ENV['RAILS_ENV']  || 'development'
  ROOT     = File.expand_path(File.join(File.dirname(__FILE__), '..'))

  # Used to indicate that the processing for a thread shoud complete
  class StopProcessingException < Interrupt #:nodoc:
  end

  # Used to indicate that the processing on a message should cease, 
  # and the message should be returned back to the broker as best it can be
  class AbortMessageException < Exception #:nodoc:
  end

  # Used to indicate that the processing on a message should cease, 
  # but no further action is required
  class StopFilterException < Exception #:nodoc:
  end

  def ActiveMessaging.logger
    @@logger = nil unless defined? @@logger
    @@logger ||= RAILS_DEFAULT_LOGGER if defined? RAILS_DEFAULT_LOGGER
    @@logger ||= ActiveRecord::Base.logger if defined? ActiveRecord
    @@logger ||= Logger.new(STDOUT)
    @@logger
  end

  # DEPRECATED, so I understand, but I'm using it nicely below.
  def self.load_extensions
    require 'logger'
    require 'activemessaging/support'
    require 'activemessaging/gateway'
    require 'activemessaging/adapter'
    require 'activemessaging/message_sender'
    require 'activemessaging/processor'
    require 'activemessaging/filter'
    require 'activemessaging/trace_filter'

    # load all under the adapters dir 
    Dir[File.join(ROOT, 'lib', 'activemessaging', 'adapters', '*.rb')].each do |a| 
      begin
        adapter_name = File.basename(a, ".rb")
        require 'activemessaging/adapters/' + adapter_name
      rescue RuntimeError, LoadError => e
        logger.debug "ActiveMessaging: adapter #{adapter_name} not loaded: #{ e.message }"
      end
    end
  end

  def self.load_config
    p APP_ROOT
    path = File.expand_path("#{APP_ROOT}/config/messaging.rb")
    p path
    begin
      load path
    rescue MissingSourceFile
      logger.debug "ActiveMessaging: no '#{path}' file to load"
    rescue
      raise $!, " ActiveMessaging: problems trying to load '#{path}': \n\t#{$!.message}"
    end
  end

  def self.load_processors(first=true)
    #Load the parent processor.rb, then all child processor classes
    load APP_ROOT + '/vendor/plugins/activemessaging/lib/activemessaging/message_sender.rb' unless defined?(ActiveMessaging::MessageSender)
    load APP_ROOT + '/vendor/plugins/activemessaging/lib/activemessaging/processor.rb' unless defined?(ActiveMessaging::Processor)
    load APP_ROOT + '/vendor/plugins/activemessaging/lib/activemessaging/filter.rb' unless defined?(ActiveMessaging::Filter)
    logger.debug "ActiveMessaging: Loading #{APP_ROOT + '/app/processors/application.rb'}" if first
    load APP_ROOT + '/app/processors/application.rb' if File.exist?("#{APP_ROOT}/app/processors/application.rb")
    Dir[APP_ROOT + '/app/processors/*.rb'].each do |f|
      unless f.match(/\/application.rb/)
        logger.debug "ActiveMessaging: Loading #{f}" if first
        load f
      end
    end
  end

  def self.reload_activemessaging
    # this is resetting the messaging.rb
    ActiveMessaging::Gateway.filters = []
    ActiveMessaging::Gateway.named_destinations = {}
    ActiveMessaging::Gateway.processor_groups = {}

    # now load the config
    load_config
    load_processors(false)
  end

  def self.load_activemessaging
    load_extensions
    load_config
    load_processors
  end

  def self.start
    if ActiveMessaging::Gateway.subscriptions.empty?
      err_msg = <<EOM   

ActiveMessaging Error: No subscriptions.
If you have no processor classes in app/processors, add them using the command:
  script/generate processor DoSomething"

If you have processor classes, make sure they include in the class a call to 'subscribes_to':
  class DoSomethingProcessor < ActiveMessaging::Processor
    subscribes_to :do_something

EOM
      puts err_msg
      logger.error err_msg
      exit
    end

    Gateway.start
  end

end

#load these once to start with
ActiveMessaging.load_activemessaging

# reload these on each Rails request - leveraging Dispatcher semantics for consistency
if defined? Rails
  ActiveMessaging.logger.info "Rails available: Adding dispatcher prepare callback."
  require 'dispatcher' unless defined?(::Dispatcher)
  
  # add processors and config to on_prepare if supported (rails 1.2+)
  if ::Dispatcher.respond_to? :to_prepare
    ::Dispatcher.to_prepare :activemessaging do
      ActiveMessaging.reload_activemessaging
    end
  end
end