module MyChart
  class XYZ
    def initialize objs_2d_hash
      @objs_2d_hash = objs_2d_hash
    end

    def value
      @objs_2d_hash
    end

    def labels
      value.keys
    end

    def datasets
      labels_in_datasets = keys_in_sub_hash value
      labels_in_datasets.map do |lb|
        {
          label: lb,
          data: value.map{ |k, sub_hash| sub_hash[lb] ? sub_hash[lb].count : 0}
        }
      end
    end

    def == obj
      obj.kind_of? XYZ and value == obj.value
    end

    private

    def keys_in_sub_hash hash_2d
      hash_2d.values.reduce([]) do |labels, hash|
        labels + hash.keys
      end.uniq.sort_by(&:to_s)
    end

  end
end