DFE-Digital/govuk-formbuilder

module GOVUKDesignSystemFormBuilder
  module Elements
    class TextArea < Base
      using PrefixableArray

      include Traits::Error
      include Traits::Hint
      include Traits::Label
      include Traits::Supplemental
      include Traits::HTMLAttributes
      include Traits::HTMLClasses

      def initialize(builder, object_name, attribute_name, hint:, label:, caption:, rows:, max_words:, max_chars:, threshold:, form_group:, **kwargs, &block)
        super(builder, object_name, attribute_name, &block)

        fail ArgumentError, 'limit can be words or chars' if max_words && max_chars

        @label           = label
        @caption         = caption
        @hint            = hint
        @max_words       = max_words
        @max_chars       = max_chars
        @threshold       = threshold
        @rows            = rows
        @form_group      = form_group
        @html_attributes = kwargs
      end

      def html
        Containers::FormGroup.new(*bound, **@form_group.merge(limit_form_group_options)).html do
          safe_join([label_element, supplemental_content, hint_element, error_element, text_area, limit_description])
        end
      end

    private

      def text_area
        @builder.text_area(@attribute_name, **attributes(@html_attributes))
      end

      def classes
        build_classes(%(textarea), %(textarea--error) => has_errors?, %(js-character-count) => limit?).prefix(brand)
      end

      def options
        {
          id: field_id(link_errors: true),
          class: classes,
          rows: @rows,
          aria: { describedby: combine_references(hint_id, error_id, supplemental_id, limit_description_id) },
        }
      end

      # Provides an id for use by the textual description of character and word limits.
      #
      # @note In order for the GOV.UK Frontend JavaScript to pick up this associated field
      #   it has to have the same id as the text area with the additional suffix of '-info'
      def limit_id
        [field_id(link_errors: true), 'info'].join('-')
      end

      def limit?
        limit_quantity.present?
      end

      def limit_quantity
        @max_words || @max_chars
      end

      def limit_type
        @max_words.present? ? 'words' : 'characters'
      end

      def limit_description
        return unless limit?

        tag.span(id: limit_id, class: limit_description_classes) do
          "You can enter up to #{limit_quantity} #{limit_type}"
        end
      end

      def limit_description_classes
        build_classes(%(hint), %(character-count__message)).prefix(brand)
      end

      def limit_description_id
        return unless limit?

        limit_id
      end

      def limit_form_group_options
        return {} unless limit?

        {
          class: %(#{brand}-character-count),
          data: { module: %(#{brand}-character-count) }.merge(**limit_max_options, **limit_threshold_options).compact
        }
      end

      def limit_max_options
        if @max_words
          { maxwords: @max_words }
        elsif @max_chars
          { maxlength: @max_chars }
        end
      end

      def limit_threshold_options
        { threshold: @threshold }
      end
    end
  end
end