food_item.rb

  def self.ranking_sort(results,query)
    results.sort { |a,b| ranking_score(a,query) <=> ranking_score(b,query) }
  end

  # Compute the two-ordered score for sorting
  #   Score is of the form [ 1 / # of matches, average distance ]
  #   This arises because we may have 1 or more query parts that aren't matched at all
  #     Since those elements return nil we can't exactly set them to 0 or MAX and expect reliable results
  #     e.g. "Carrot Soup" === ["carrot","soup"] = (0 + 8) / 2 = 4   # Clearly the best result
  #          "Carrot's, raw" === ["carr...soup"] = (0 + 0?) / 2 = 0  # but setting to 0 breaks this
  #          # Additionally setting the value arbitrarily high may cull results that are otherwise close but missing a word
  def self.ranking_score(item,query)
    queries = query.split
    text = item.name
    matches = 0

    total = queries.inject(0) do |sum, query|
      # "Carrot SoUp" -> "carrot soup" # we need to match properly
      distance = text.downcase.index(query.downcase)
      if distance
        matches += 1
        sum + distance
      else
        sum
      end
    end

    avg_distance = total / query.size
    # Set the reciprocal appropriately so no matches sorts to the end
    reciprocal = matches && matches > 0 ? matches : queries.size + 1

    #TODO: Try mixing the last two pieces together with coefficients - currently not a composite :(
    #  e.g. d * avg_distance + l * Absolute Length Difference
    #       where d and l are coefficients representing the importance of either factor
    [ reciprocal, avg_distance, (text.length - query.length).abs]
  end