module ActiveScaffold
  module Bridges
    module Paperclip
      module Lib
        module FileColumnHelpers
          class << self
            def file_column_fields(klass)
              klass.instance_methods.grep(/_just_uploaded\?$/).collect{|m| m[0..-16].to_sym }
            end
            
            def generate_delete_helpers(klass)
              file_column_fields(klass).each { |field|
                klass.send :class_eval, <<-EOF, __FILE__, __LINE__ + 1  unless klass.methods.include?("#{field}_with_delete=")
                  attr_reader :delete_#{field}
                  
                  def delete_#{field}=(value)
                    value = (value=="true") if String===value
                    return unless value
                    
                    # passing nil to the file column causes the file to be deleted.  Don't delete if we just uploaded a file!
                    self.#{field} = nil unless self.#{field}_just_uploaded?
                  end
                EOF
              }
            end
            
            def klass_has_file_column_fields?(klass)
              true unless file_column_fields(klass).empty?
            end
          end
          
          def file_column_fields
            @file_column_fields||=FileColumnHelpers.file_column_fields(self)
          end
          
          def options_for_file_column_field(field)
            self.allocate.send("#{field}_options")
          end
          
          def field_has_image_version?(field, version="thumb")
            begin
              # the only way to get to the options of a particular field is to use the instance method
              options = options_for_file_column_field(field)
              versions = options[:magick][:versions]
              raise unless versions.stringify_keys[version]
              true
            rescue
              false
            end
          end
          
          def generate_delete_helpers
            FileColumnHelpers.generate_delete_helpers(self)
          end
        end
      end
    end
  end
end