class StepNavHelper
  include ActionView::Helpers
  include ActionView::Context

  def render_step_nav_element(element, options)
    @options = options
    @link_index = options[:link_index]

    case element[:type]
    when "paragraph"
      paragraph(element[:text])
    when "heading"
      heading(element[:text])
    when "list"
      list(element)
    end
  end

  # id should be lowercase, contain only numbers and letters and replace spaces with dashes
  def generate_step_nav_id(step_title)
    step_title.downcase.tr(" ", "-").gsub(/[^a-z0-9\-\s]/i, '')
  end

private

  def paragraph(text)
    content_tag(
      :p,
      text,
      class: "gem-c-step-nav__paragraph"
    )
  end

  def heading(text)
    content_tag(
      "h#{@options[:heading_level] + 1}",
      text,
      class: "gem-c-step-nav__heading"
    )
  end

  def list(element)
    content_tag(
      get_list_element(element[:style]),
      class: "gem-c-step-nav__links #{get_list_style(element[:style])}",
      data: {
        length: element[:contents].length
      }
    ) do
      element[:contents].collect { |contents|
        concat(
          content_tag(
            :li,
            class: "gem-c-step-nav__link js-list-item #{link_active(contents[:active])}"
          ) do
            create_list_item_content(contents)
          end
        )
      }
    end
  end

  def create_list_item_content(link)
    if link[:href]
      @link_index += 1
      href = link_href(link[:active], link[:href])
      text = "#{link_text(link[:active], link[:text])} #{create_context(link[:context])}".html_safe

      link_to(
        href,
        rel: ("external" if href.start_with?('http')),
        data: {
          position: "#{@options[:step_index] + 1}.#{@link_index}"
        },
        class: "gem-c-step-nav__link-item js-link"
      ) do
        text
      end
    else
      link[:text]
    end
  end

  def create_context(context)
    content_tag(:span, context, class: "gem-c-step-nav__context") if context
  end

  def get_list_style(style)
    "gem-c-step-nav__links--choice" if style == "choice"
  end

  def get_list_element(style)
    style == "choice" ? "ul" : "ol"
  end

  def link_href(active, href)
    active ? "#content" : href
  end

  def link_text(active, text)
    active ? content_tag(:span, "You are currently viewing: ", class: "visuallyhidden") + text : text
  end

  def link_active(active)
    "gem-c-step-nav__link--active" if active
  end
end