=begin rdoc
Author::    Chris Hauboldt (mailto:biz@lnstar.com)
Copyright:: 2009 Lone Star Internet Inc.

Newsletter::Elements define the way a Newsletter::Piece looks with an erb design and the data it can hold with Newsletter::Fields. They can exist in multiple Newsletter::Areas, but currently belong to only 1 design.

=end

module Newsletter
  class Element < ActiveRecord::Base
    self.table_name =  "#{::Newsletter.table_prefix}elements"
    has_and_belongs_to_many :areas, :class_name => 'Newsletter::Area',
      :join_table => "#{::Newsletter.table_prefix}areas_#{::Newsletter.table_prefix}elements"
    has_many :fields, :order => 'sequence', :class_name => 'Newsletter::Field'
    has_many :pieces, :class_name => 'Newsletter::Piece'
    belongs_to :design, :class_name => 'Newsletter::Design'
    belongs_to :updated_by, :class_name => 'User'
  
    scope :by_design, lambda{|design| {:conditions =>{:design_id => design.id}}}
  
    validates_presence_of :name

    accepts_nested_attributes_for :fields

    attr_protected :id
    #FIXME: make this work with deletable or convert to auditable, and extend it to access destroyed records
    #validates_uniqueness_of :name, :scope => :design_id
  
    # defines the design path for the element as used in a render :partial => (without '_')
    def view_path(this_name=nil)
        this_name = self[:name] unless this_name
          "#{::Newsletter.designs_path}/designs/#{design.name.gsub(/[^a-zA-Z0-9-]/,'_')}/elements/#{name_as_path(this_name)}.html.erb"
    end
  
    # returns a version of name that is nice for filesytem use
    def name_as_path(this_name=nil)
      this_name = name unless this_name
      this_name.gsub(/[^a-zA-Z0-9-]/,'_').downcase
    end
  
    # defines where the file is in the filesystem
    def file_path(this_name=nil)
      File.dirname(view_path(this_name)) + '/_' + File.basename(view_path(this_name))
    end
  
    # used to record old name of an element such that the design can be moved to the new name
    def name=(new_name)
      return if self[:name].eql?(new_name)
      @old_name = self[:name] unless @old_name
      self[:name] = new_name
    end
  
    # retrieves the html erb design from the file system
    def html_text
      return @html_text if @html_text.present?
      @html_text = read_design
    end

    # sets and saves the html erb design to update the file after a successful save
    def html_text=(text)
      @html_text = text
    end
  
    # returns field data so that Newsletter::Design.export(instance) can export itself to a YAML file  
    def export_fields
      { :name => name,
        :description => description,
        :html_text => html_text,
        :areas => areas.collect{|area| area.export_fields},
        :fields => fields.collect{|field| field.export_fields}
      }
    end
  
    # builds areas from data pulled out of an exported YAML file by Newsletter::Design.import(class)  
    def self.import(design,data)
      element = Element.new(:name => data[:name], 
        :html_text => data[:html_text],
        :description => data[:description])
      element.design = design
      element.save
      data[:areas].each do |area_data|
        element.areas <<
          Area.find_all_by_design_id_and_name(design.id,area_data[:name])
      end
      data[:fields].each do |field_data|
          Field.import(element,field_data)
      end
    end
  
    def save(*args)
      transaction do 
        move_design_on_name_change
        write_design
        super
      end
    end
  
    include Deleteable
    protected
    def read_design
      File.readlines(file_path).join
    rescue => e
      #send back an empty string if no file exists yet for the design... don't raise an error
      ""
    end
  
    def write_design
      FileUtils.mkdir_p(File.dirname(file_path)) unless File.exists?(File.dirname(file_path))
      File.open(file_path,File::WRONLY|File::TRUNC|File::CREAT) do |file|
        file.write html_text
      end
    end
  
    def move_design_on_name_change
      return unless @old_name and File.exists?(file_path(@old_name))
      FileUtils.mv(file_path(@old_name),file_path)
    end
  
  end
end