module ETL #:nodoc:
  module Transform #:nodoc:
    # Transform which decodes coded values
    class DecodeTransform < ETL::Transform::Transform
      attr_accessor :decode_table_path, :decode_table_delimiter, :default_value
      def initialize(control, configuration={})
        super
        
        if configuration[:decode_table_path]
          configuration[:decode_table_path] = File.join(File.dirname(control.file), configuration[:decode_table_path])
        end
        
        @decode_table_path = (configuration[:decode_table_path] || 'decode.txt')
        @decode_table_delimiter = (configuration[:decode_table_delimiter] || ':')
        @default_value = (configuration[:default_value] || 'No Value')
      end
      def transform(value)
        decode_table[value] || default_value
      end
      
      def decode_table
        unless @decode_table
          @decode_table = {}
          open(decode_table_path).each do |line|
            code, value = line.strip.split(decode_table_delimiter)
            if code && code.length > 0
              @decode_table[code] = value
            else
              @default_value = value
            end
          end
        end
        @decode_table
      end
    end
  end
end