ReferentialDecorator: Handle non-`Link` buttons

Referentials#show has a button "Purger" that isn't a link. Instead, it's
a `<button>` element that opens a modal.

Previously, we only knew how to put `Link`s in the `#action_links`, and
only these could then be rendered in the header bar as buttons.

This change allows us to accept non-Link objects. Since the button is
rather simple, I decided to create a simple `HTMLElement` class to
represent it and output it in the resulting HTML. The class uses the
`#content_tag` `ActionView` helper to render the final HTML.

Update "referentials/show.html.slim" to output the button correctly in
addition to the normal links.

Update `TableBuilderHelper#build_links` to not add anything that's not a
`Link` to the gear menu. This allows us to display the "Purger" button
on the Referentials#show page but not in the table on Workbenches#show.

Refs #3479

4 files changed, 33 insertions, 8 deletions

diff --git a/app/decorators/referential_decorator.rb b/app/decorators/referential_decorator.rb
index 58c2eac73..9107de0b3 100644
--- a/app/decorators/referential_decorator.rb
+++ b/app/decorators/referential_decorator.rb
@@ -17,8 +17,15 @@ class ReferentialDecorator < Draper::Decorator
     end
 
     if h.policy(object).edit?
-      # TODO: Handle buttons in the header and don't show them in the gear menu
-      # button.btn.btn-primary type='button' data-toggle='modal' data-target='#purgeModal' Purger
+      links << HTMLElement.new(
+        :button,
+        'Purger',
+        type: 'button',
+        data: {
+          toggle: 'modal',
+          target: '#purgeModal'
+        }
+      )
 
       if object.archived?
         links << Link.new(
diff --git a/app/helpers/table_builder_helper.rb b/app/helpers/table_builder_helper.rb
index 111237a7b..97370b7e0 100644
--- a/app/helpers/table_builder_helper.rb
+++ b/app/helpers/table_builder_helper.rb
@@ -112,7 +112,7 @@ module TableBuilderHelper
     menu = content_tag :ul, class: 'dropdown-menu' do
       (
         CustomLinks.new(item, pundit_user, links).links +
-        item.action_links
+        item.action_links.select { |link| link.is_a?(Link) }
       ).map do |link|
         gear_menu_link(link)
       end.join.html_safe
diff --git a/app/views/referentials/show.html.slim b/app/views/referentials/show.html.slim
index f3dcf6a69..2e67f4968 100644
--- a/app/views/referentials/show.html.slim
+++ b/app/views/referentials/show.html.slim
@@ -27,11 +27,14 @@
       /    span = t('actions.destroy')
       /= leslinks.map { |l| link_to l.href, l.label }
       - @referential.action_links.each do |link|
-        = link_to link.href,
-            method: link.method,
-            data: link.data,
-            class: 'btn btn-primary' do
-              = link.content
+        - if link.is_a?(HTMLElement)
+          = link.to_html(class: 'btn btn-primary')
+        - else
+          = link_to link.href,
+              method: link.method,
+              data: link.data,
+              class: 'btn btn-primary' do
+                = link.content
 
 / PageContent
 .page_content
diff --git a/lib/html_element.rb b/lib/html_element.rb
new file mode 100644
index 000000000..469fd7565
--- /dev/null
+++ b/lib/html_element.rb
@@ -0,0 +1,15 @@
+class HTMLElement
+  def initialize(tag_name, content = nil, options = nil)
+    @tag_name = tag_name
+    @content = content
+    @options = options
+  end
+
+  def to_html(options = {})
+    ApplicationController.helpers.content_tag(
+      @tag_name,
+      @content,
+      @options.merge(options)
+    )
+  end
+end