require 'jsduck/logger'

module JsDuck
  module Process

    # Checks for circular dependencies
    class CircularDeps
      def initialize(classes)
        @classes = classes
      end

      # Checks all classes for circular dependencies.
      #
      # When found, exits with a fatal error message.
      def process_all!
        @classes.each do |cls|
          if chain = check(cls)
            Logger.fatal("Class #{cls[:name]} has a circular dependency: #{chain}")
            exit 1
          end
        end
      end

      # Checks class for circular dependencies.
      #
      # When all OK, returns false.
      #
      # When circular dependencies found returns a string describing the
      # problematic dependency chain e.g. "Foo extends Bar mixins Foo".
      def check(cls, names = [])
        names += [cls[:name]]

        if cls.parent && chain = track_circular(" extends ", cls.parent, names)
          return chain
        end

        cls.mixins.each do |mixin|
          if chain = track_circular(" mixins ", mixin, names)
            return chain
          end
        end

        false
      end

      def track_circular(type, cls, names)
        names += [type]
        if names.include?(cls[:name])
          (names + [cls[:name]]).join("")
        else
          check(cls, names)
        end
      end

    end

  end
end