require 'facets/more/aspects'

module Glue

# This module adds cleanup functionality to managed 
# classes. Override and implement sweep_affected.
# Typically used to cleanup output caching files from
# the filesystem. But you can also use it to clean up
# temp objects in the database or other temp files.
#--
# FIXME: find a better name.
#++

module Sweeper
  include Aspects

  #--
  # Inject the sweepers *after* the event to have a valid
  # oid.
  #++
    
  before "sweep_affected(:insert)", :on => :og_insert
  before "sweep_affected(:update)", :on => :og_update
  before "sweep_affected(:delete)", :on => :og_delete

  # Expires (deletes) a cached page from the file system.
  #
  # == Input
  #
  # * relative = if set to true, prepends the controller 
  #   mount path.
  #--
  # FIXME: replace with 'extend Nitro::Caching::Output' ?
  # this way we wont have to sync the same code in two different
  # places.
  # If you change this method, don't forget the Caching::Output
  # expire method.  
  #++
  
  def self.expire(name, klass, relative = false)
    if relative and controller = klass.ann.self[:controller]
      filename = "#{Server.public_root}/#{controller.mount_path}/#{name}.html".squeeze('/')
    else
      filename = "#{Server.public_root}/#{name}.html".squeeze('/')
    end
    Logger.debug "Sweeper expired cache file '#{filename}'" if $DBG
    FileUtils.rm_rf(filename)
  rescue Object => ex
    # ignore any error.
  end

private

  # If needed pass the calling action symbol to allow
  # for conditional expiration.
  # Action takes values from { :insert, :delete, :update }
  # or your own custom enumeration.
  #
  # Generally add lines like the following:
  #
  # expire_affected_output('file_to_expire')
    
  def sweep_affected(action = :all)
  end
  alias_method :expire_affected, :sweep_affected
  
  # Called from an action that modifies the model to expire 
  # affected (dependend) cached pages. Generally you don't 
  # override this method.
  #
  # == Input
  #
  # * relative = if set to true, prepends the controller 
  #   mount path.
    
  def expire_affected_output(name, relative = true)
    Sweeper.expire(name, self.class, relative)
  end
  alias_method :expire_output, :expire_affected_output

  # Expire affected cached fragments.
  
  def expire_affected_fragment(name, options = {})
    Nitro::Caching::Fragments.cache.delete(name, options)
  end
  alias_method :expire_fragment, :expire_affected_fragment
  
end

end