haml--haml/lib/hamlit/compilers/attributes.rb

require 'hamlit/compilers/new_attribute'
require 'hamlit/compilers/old_attribute'

module Hamlit
  module Compilers
    module Attributes
      include Compilers::NewAttribute
      include Compilers::OldAttribute

      def on_haml_attrs(*attrs)
        attrs = compile_attributes(attrs)
        attrs = join_ids(attrs)
        attrs = combine_classes(attrs)
        attrs = pull_class_first(attrs)
        [:html, :attrs, *attrs]
      end

      private

      def compile_attributes(exps)
        attrs = []
        exps.each do |exp|
          case exp
          when /\A\(.+\)\Z/
            attrs += compile_new_attribute(exp)
          when /\A{.+}\Z/
            attrs += compile_old_attribute(exp)
          else
            attrs << compile(exp)
          end
        end
        attrs
      end

      def pull_class_first(attrs)
        class_attrs = filter_attrs(attrs, 'class')
        combine_classes(class_attrs) + (attrs - class_attrs)
      end

      def combine_classes(attrs)
        class_attrs = filter_attrs(attrs, 'class')
        return attrs if class_attrs.length <= 1

        values = class_attrs.map(&:last).sort_by(&:last)
        [[:html, :attr, 'class', [:multi, *insert_static(values, ' ')]]] + (attrs - class_attrs)
      end

      def join_ids(attrs)
        id_attrs = filter_attrs(attrs, 'id')
        return attrs if id_attrs.length <= 1

        values = attrs.map(&:last)
        [[:html, :attr, 'id', [:multi, *insert_static(values, '_')]]] + (attrs - id_attrs)
      end

      def filter_attrs(attrs, target)
        class_attrs = attrs.select do |html, attr, name, content|
          name == target
        end
      end

      def insert_static(array, str)
        result = []
        array.each_with_index do |value, index|
          result << [:static, str] if index > 0
          result << value
        end
        result
      end
    end
  end
end