module JsDuck
  module Categories

    # Automatically divides all available classes into categories
    class Auto
      def initialize(relations)
        @relations = relations
      end

      # Performs the generation
      def generate
        # list names of all public classes
        class_names = @relations.to_a.find_all {|cls| !cls[:private] }.map {|cls| cls[:name] }

        # divide classes into top-level categories by namespace
        categories = categorize(class_names)

        # in each category, create sub-categories
        categories.each_pair do |ns, classes|
          categories[ns] = categorize(classes, 1)
        end

        # Turn categories hash into array, sort everything
        categories_array = []
        categories.each_pair do |ns, groups|
          groups_array = []
          groups.each_pair do |gns, classes|
            groups_array << {
              "name" => gns,
              "classes" => classes.sort
            }
          end
          groups_array.sort! {|a, b| cat_compare(a, b) }
          categories_array << {
            "name" => ns,
            "groups" => groups_array
          }
        end
        categories_array.sort! {|a, b| cat_compare(a, b) }

        return categories_array
      end

      # Divides classes into categories by namespace.  Collapses
      # categories having only one class into a category "Others..."
      def categorize(class_names, level=0)
        categories = {}
        class_names.each do |name|
          ns = name.split(/\./)[level] || name.split(/\./)[0]
          categories[ns] = [] unless categories[ns]
          categories[ns] << name
        end

        globals = []
        categories.each_pair do |ns, classes|
          if classes.length == 1
            globals << classes[0]
            categories.delete(ns)
          end
        end
        if globals.length > 0
          categories["Others..."] = globals
        end

        categories
      end

      # Comparison function for sorting categories that always places
      # "Others..." category at the end.
      def cat_compare(a, b)
        if a["name"] == "Others..."
          1
        elsif b["name"] == "Others..."
          -1
        else
          a["name"] <=> b["name"]
        end
      end

    end

  end
end