radar/twist-v2

module Twist
  module Web
    module GraphQL
      module Resolvers
        module Section
          class ByChapter < BaseResolver
            type [Types::Section], null: false

            def resolve
              build_sections(build_hierarchy(context[:element_repo], object.id))
            end

            private

            # rubocop:disable Metrics/MethodLength
            def build_hierarchy(element_repo, chapter_id)
              headers = element_repo.sections_for_chapter(chapter_id)

              hierarchy = []
              current_section = { subsections: [] }

              headers.each do |header|
                case header.tag
                when "h2"
                  current_section = build_section(header, true)
                  hierarchy << current_section
                when "h3"
                  current_section[:subsections] << build_section(header, false)
                end
              end

              hierarchy
            end
            # rubocop:enable Metrics/MethodLength

            def build_sections(hierarchy)
              hierarchy.map do |item|
                item[:subsections].map! do |subitem|
                  Twist::Entities::Section.new(subitem.merge(subsections: []))
                end

                Twist::Entities::Section.new(item)
              end
            end

            def build_section(element, subsections = false)
              title = extract_text(element.content)

              section = {
                id: element.id,
                tag: element.tag,
                title: title,
                link: slugify(title),
              }

              section[:subsections] = [] if subsections

              section
            end

            def extract_text(content)
              Nokogiri::HTML.fragment(content).text
            end

            def slugify(title)
              title.gsub(/^[\d|.]+/, "").to_slug.normalize.to_s
            end
          end
        end
      end
    end
  end
end