FEATURE: use original filename when clicking the download link in the lightbox

lib/cooked_post_processor.rb

@@ -159,6 +159,11 @@ class CookedPostProcessor
     # then, the link to our larger image
     a = Nokogiri::XML::Node.new("a", @doc)
     img.add_next_sibling(a)
+
+    if upload && Discourse.store.internal?
+      a["data-download-href"] = Discourse.store.download_url(upload)
+    end
+
     a["href"] = img["src"]
     a["class"] = "lightbox"
     a.add_child(img)
@@ -217,9 +222,11 @@ class CookedPostProcessor
   end
 
   def optimize_urls
-    @doc.css("a[href]").each do |a|
-      href = a["href"].to_s
-      a["href"] = schemaless absolute(href) if is_local(href)
+    %w{href data-download-href}.each do |selector|
+      @doc.css("a[#{selector}]").each do |a|
+        href = a["#{selector}"].to_s
+        a["#{selector}"] = schemaless absolute(href) if is_local(href)
+      end
     end
 
     @doc.css("img[src]").each do |img|
@@ -243,17 +250,17 @@ class CookedPostProcessor
   end
 
   def disable_if_low_on_disk_space
-    if available_disk_space < SiteSetting.download_remote_images_threshold
-      SiteSetting.download_remote_images_to_local = false
-      # log the site setting change
-      reason = I18n.t("disable_remote_images_download_reason")
-      staff_action_logger = StaffActionLogger.new(Discourse.system_user)
-      staff_action_logger.log_site_setting_change("download_remote_images_to_local", true, false, { details: reason })
-      # also send a private message to the site contact user
-      SystemMessage.create_from_system_user(Discourse.site_contact_user, :download_remote_images_disabled)
-      return true
-    end
-    false
+    return false if available_disk_space >= SiteSetting.download_remote_images_threshold
+
+    SiteSetting.download_remote_images_to_local = false
+    # log the site setting change
+    reason = I18n.t("disable_remote_images_download_reason")
+    staff_action_logger = StaffActionLogger.new(Discourse.system_user)
+    staff_action_logger.log_site_setting_change("download_remote_images_to_local", true, false, { details: reason })
+    # also send a private message to the site contact user
+    SystemMessage.create_from_system_user(Discourse.site_contact_user, :download_remote_images_disabled)
+
+    true
   end
 
   def available_disk_space