module Lookbook
  class Navigation
    class << self
      def previews
        valid_previews = ViewComponent::Preview.all.filter { |preview| preview.get_visible_examples.any? && !preview.hidden? }
        valid_previews.sort_by(&:normalized_name)
      end

      def flat
        {
          flat: true,
          depth: 0,
          items: previews.map do |preview|
            nav_item_for_preview(preview, expand_name: true)
          end
        }
      end

      def nested
        nav = {flat: false, depth: 0, items: []}
        previews.each do |preview|
          current = nav
          depth = preview.path_parts.size
          path = ""
          preview.path_parts.each_with_index do |segment, i|
            target = current[:items].find { |item| item[:name] == segment }
            if target.nil?
              path = "#{path.present? ? path + "." : ""}#{segment}"
              target = {
                depth: i + 1,
                nested: true,
                name: path,
                label: segment.titleize,
                type: :group,
                items: []
              }
              current[:items].append(target)
            end
            if depth == i + 1
              target[:items].push(nav_item_for_preview(preview))
            else
              current = target
            end
          end
        end
        nav
      end

      private

      def nav_item_for_preview(preview, expand_name: false)
        {
          name: preview.preview_name.tr("/", "."),
          label: expand_name ? "#{preview.pretty_path}/#{preview.label}" : preview.label,
          type: :preview,
          examples: preview.get_visible_examples.map do |example|
            example_path = "#{preview.preview_name}/#{example.name}"
            {
              name: example.name,
              label: example.label,
              path: example_path
            }
          end
        }
      end
    end
  end
end