CM-420 add GovspeakEditor to govspeak-enabled textareas

[edavey]

Add GovspeakEditor to govspeak-enabled textareas

See Jira CM-420

In this PR we:

• copy over a simplified version of the mechanism in use on Whitehall for toggling between "Edit" and "Preview" modes on textareas. For now we omit the handling of attachments and images which Whitehall's GovspeakHelper supports. Our content block textareas are much smaller and simpler than the document-scale textareas available in Whitehall
• remove an unused Whitehall::GovspeakRenderer helper class which was brought over from Whitehall but is not used

---

Notes on use of Govspeak

1) GovspeakEditor: when editing content (implemented in this PR)

When composing or editing a govspeak-enabled <textarea> we offer users the facility to toggle between "Preview" and "Edit" modes.

When choosing to "Preview" the content of the textarea, we use Ajax to send a POST request to the /admin/preview endpoint. The Admin::PreviewController uses the GovspeakPreviewHelper which ultimately calls #to_haml on a new Govspeak::Document, defined in the govspeak gem, a dependency of the content_block_tools gem.

2) render_govspeak: when displaying saved content

When displaying govspeak-enabled fields which have been saved, on workflow pages such as:

• editions/1/workflow/group_contact_methods#telephones or
• editions/1/workflow/review

the EmbeddedObjects::SummaryCard::NestedItemComponent uses the ContentBlockManager::ContentBlock::GovspeakHelper and calls out to render_govspeak in the content_block_tools gem:

module ContentBlockTools
  module Govspeak
    def render_govspeak(body, root_class: nil)
      html = ::Govspeak::Document.new(body).to_html
      Nokogiri::HTML.fragment(html).tap { |fragment|
        fragment.children[0].add_class(root_class) if root_class
      }.to_s.html_safe
    end
  end
end

3) DefaultBlockComponent: rendering entire block

Once a content block is published and can be viewed on the "show" block page: e.g. /content-block/1, we use the DefaultBlockComponent which renders the block using the content_block_tools gem:

ContentBlockTools::ContentBlock.new(
  document_type: "content_block_#{block_type}",
  content_id: document.content_id,
  title:,
  details:,
  embed_code:,
).render

When rendering the ContactComponent, for example, the content_block_tools gem uses ContentBlockTools::Govspeak::render_govspeak (see [2]) on the govspeak-enabled fields. See the telephone_component.html.erb:

<% if show_video_relay_service? %>
  <%= render_govspeak(video_relay_service_content) %>
<% end %>

<% if show_bsl_guidance? %>
  <%= render_govspeak(bsl_guidance[:value], root_class: "content-block__body") %>
<% end %>

<% if show_opening_hours? %>
  <%= render_govspeak(opening_hours[:opening_hours], root_class: "content-block__body") %>
<% end %>

Notes

• Currently the only fields which can be govspeak enabled are on embedded objects (aka "nested objects", "nested items"). It will take a bit of work to make GovspeakEnabledTextareaComponent general-purpose, as currently govspeak-enabled? is defined only on EmbeddedSchema.

• We have two similarly named helpers which ought to be combined:

  1. GovspeakPreviewHelper used by GovspeakEditor
  2. GovspeakHelper used by NestedItemComponent

• We also had (copied over from Whitehall but now deleted) a Whitehall::GovspeakRenderer which inherits from ActionController::Renderer and provides the following helpers methods:

  • govspeak_edition_to_html
  • govspeak_to_html
  • govspeak_with_attachments_to_html
  • govspeak_html_attachment_to_html
  • block_attachments

[pezholio]

Might be better to use the content_tag helper here

[edavey]

yes, but for now I'm just lifting and shifting selected code from Whitehall, so I'd prefer to do refactoring later to avoid any unintended side-effects.

[edavey]

@pezholio this is ready for another look now

[pezholio]

LGTM 👍