class Rtml::Document < ActiveRecord::Base
  @@ruleset_file = File.expand_path(File.join(defined?(Rails) ? Rails.root : ".", "config/tml_dom_ruleset.rb"))
  @@ruleset_file = File.expand_path(File.join(Rtml.root, "rails_generators/rtml/templates/config/tml_dom_ruleset.rb")) unless File.file?(@@ruleset_file)
  include Rtml::DSL
  include Rtml::Widgets
  include ActionController::Layout
  layout :layout
  
  set_table_name 'rtml_documents'
  has_one :root, :class_name => 'Rtml::Dom::Element', :as => :parent, :autosave => true
  has_many :instructions, :class_name => 'Rtml::Instruction', :as => :source, :autosave => true
  attr_reader :rules, :controller
  delegate :render, :view_paths, :view_paths=, :to => :view
  delegate :request, :response, :params, :flash, :to => :controller

  validates_presence_of :name
  validates_uniqueness_of :name

  def initialize_with_default_document(attributes = nil)
    if attributes
      @controller = attributes.delete(:controller)
      @initialize_to_empty = attributes.delete(:empty)
      apply_document_options(attributes)
    end
    initialize_without_default_document(attributes)
  end

  include Rtml::InheritedInstanceVariables
  protected_instance_variables.concat ["@controller", "@changed_attributes", "@view", "@new_record", "@initialize_to_empty", "@widget_instances", "@rules", "@root", "@attributes_cache", "@attributes"]
  
  def after_initialize
    @rules = Rtml::Document.rules
    if new_record? && !@initialize_to_empty
      setup_default_document
    end
  end

  # This calls root.target, because root is technically an Association object, and target retrieves the actual object.
  # This resolves ambiguities such as root.build(), which exists as both an Association method (build a new root object)
  # and as a Widget method (build a new RTML Element).
  def root_with_target
    root_without_target.nil? ? nil : root_without_target.target
  end

  alias_method_chain :root, :target

  def layout(assignment = :_no_assignment)
    if assignment != :_no_assignment
      @layout_file = assignment
    else
      @layout_file
    end
  end

  def default_template_format
    :rtml
  end

  def cache(setting)
    case setting
      when :on, true, 'on', 'true', 'yes', 'allow', :yes, :allow
        setting = 'allow'
      when :off, false, 'off', 'false', 'no', 'deny', :no, :deny
        setting = 'deny'
    end
    root.property('cache', setting)
  end

  # Resets this document so that it contains no elements, and then follows the instructions associated with this
  # document.
  def follow_instructions!
    reset!
    instructions.each { |instruction| instruction.follow(self) }
    self
  end

  # Valid options include
  #    :view_path => String
  #    :view_paths => Array of Strings
  # and are removed from the hash as they are processed.
  #
  # Invalid options are dropped silently.
  #
  def apply_document_options(options)
    options.each do |key, value|
      case key.to_s
        when 'view_path', 'view_paths'
          options.delete key
          value = [value] unless value.kind_of?(Array)
          self.view_paths = value.collect { |path| File.exist?(path) ? path : File.join(Rails.root, path) }
        #else raise ArgumentError, "Key ungrecognized: #{key.inspect}"
      end
    end
  end

  alias_method_chain :initialize, :default_document

  def reset!
    #elements.destroy_all
    #self.elements = []
    root.destroy if root
    self.root = nil
    setup_default_document
    self
  end

  def view
    return @view if @view
    @view = ActionView::Base.new(Rails.configuration.view_path, {}, @controller)
    @view.helpers.send :include, @controller.class.master_helper_module if @controller
    @view.template_format = 'rtml'
    @view
  end

  def /(name)
    if name == root.name then [root]
    else root / name
    end
  end

  def screens
    root ? root.elements.select { |ele| ele.name == 'screen' } : []
  end

  def to_tml
    during_finalization_blocks.each { |i| self.process(&i) }
    ("<?xml version=\"1.0\" encoding=\"ISO-8859-1\"?>\n" + (root ? root.to_tml : '')).gsub(/\t/, '  ')
  end

  # You can associate a block with this method, and the block will be called as a callback when self#to_tml
  # is called.
  def during_finalization(&block)
    during_finalization_blocks << block
  end

  class << self
    def ruleset_file
      @@ruleset_file
    end

    def rules
      Rtml::Rules::DomRuleset.parse(ruleset_file)
    end
  end

  private
  def during_finalization_blocks
    @during_finalization_blocks ||= []
  end
end