fix issues with the image upload description markdown input

lib/philomena_web/templates/image/new.html.slime

@@ -65,7 +65,7 @@
   .field
     .block
       .communication-edit__wrap
-        = render PhilomenaWeb.MarkdownView, "_input.html", conn: @conn, f: f, action_icon: "pencil-alt", action_text: "Description", placeholder: "Describe this image in plain words - this should generally be info about the image that doesn't belong in the tags or source.", required: false
+        = render PhilomenaWeb.MarkdownView, "_input.html", conn: @conn, f: f, action_icon: "pencil-alt", action_text: "Description", placeholder: "Describe this image in plain words - this should generally be info about the image that doesn't belong in the tags or source.", name: :description, class: "js-image-input", required: false
 
   = render PhilomenaWeb.MarkdownView, "_anon_checkbox.html", conn: @conn, f: f, label: "Post anonymously"
 

lib/philomena_web/templates/markdown/_input.html.slime

@@ -3,6 +3,8 @@
 - action_icon = assigns[:action_icon] || 'edit'
 - field_name = assigns[:name] || :body
 - field_placeholder = assigns[:placeholder] || "Your message"
+- is_required = assigns[:required]
+- input_classes = assigns[:class]
 .block__header.block__header--js-tabbed
   a.selected href="#" data-click-tab="write"
     i.fa> class="fa-#{action_icon}"
@@ -18,7 +20,7 @@
   = render PhilomenaWeb.MarkdownView, "_toolbar.html", conn: @conn
 
   .field
-    = textarea form, field_name, class: "input input--wide input--text input--resize-vertical js-toolbar-input js-preview-input", placeholder: field_placeholder, required: required?(@conn)
+    = textarea form, field_name, class: add_classes("input input--wide input--text input--resize-vertical js-toolbar-input js-preview-input", input_classes), placeholder: field_placeholder, required: required?(is_required)
     = error_tag form, field_name
 
 .block__tab.communication-edit__tab.hidden.js-preview-content data-tab="preview"

lib/philomena_web/views/markdown_view.ex

@@ -5,6 +5,9 @@ defmodule PhilomenaWeb.MarkdownView do
     conn.assigns.current_user.anonymous_by_default
   end
 
-  def required?(%{assigns: %{required: false}}), do: nil
+  def required?(required) when required == false, do: nil
   def required?(_), do: true
+
+  def add_classes(base_classes, new_classes) when is_binary(new_classes), do: "#{base_classes} #{new_classes}"
+  def add_classes(base_classes, _), do: base_classes
 end