module Rtml::DSL
  # Processes the given block using the RTML DSL
  # Examples:
  #  tml_docs = Rtml::Document.new
  #  tml_docs.process_block do
  #    # scope is transferred to the element
  #    screen :init, :next => :idle do
  #      display
  #    end
  #  end
  #
  #  tml_docs.process_block do |document|
  #    # scope is maintained and element is referenced explicitly
  #    document.screen :init, :next => :idle do |scr|
  #      scr.display
  #    end
  #
  #    # note that these approaches are interchangeable:
  #    document.screen :idle do
  #      display
  #    end
  #  end
  #
  def process(&block)
    # arity == -1 is bug 574 in Ruby 1.8 -- should be 0. It's of no consequence in this case.
    if block.arity == 0 || block.arity == -1 then self.instance_eval &block
    else block.call(self)
    end
  end

  # Constructs and returns a new instance of Rtml::Dom::Element. If Rtml::Dom::[name]Element exists, that is built
  # instead. The model is added to the "elements" array (if available), but not saved.
  def build_element(name, properties = {})
    document = self.respond_to?(:document) ? self.document :
            (self.respond_to?(:parent) && parent ? parent.document : self)
    type = begin
      ("Rtml::Dom::#{name.to_s.camelize}Element".constantize)
    rescue NameError
      Rtml::Dom::Element
    end
    #if new_record? || changed?
      element = type.new(:name => name, :document => document)
      if respond_to?(:elements)
        elements << element
      elsif respond_to?(:root)
        root = element
      end
#      element = elements.build(:name => name, :document => document, :type => type.to_s)
#      element.document = document if element.respond_to?(:document)
      element.parent = self if element.respond_to?(:parent)
#    else
#      element = type.create!(:name => name, :document => document)
#      if respond_to?(:elements)
#        elements << element
#      elsif respond_to?(:root)
#        self.root = element
#      end
#      #element = elements.create!(:name => name, :document => document, :type => type.to_s)
#    end
    #element = type.new(:name => name, :document => document)
    #self.elements << element if respond_to?(:elements)
#    element = if respond_to?(:elements) && elements.respond_to?(:build)
#      el = self.elements.build(:name => name, :document => document)
#      el.type = type.to_s
#      el
#    else
#      element = type.new(:name => name, :document => document)
#      self.elements << element if respond_to?(:elements)
#      element
#    end
    properties.each { |key, value| element.property key, value }
    if respond_to?(:root) && !self.root
      self.root = element
    end
    element
  end

  # backward compatibility to RTML 1
  alias process_block process
  deprecate :process_block
end