FIX: ensure local images use local CDN when uploads are stored on S3

When the S3 store was enabled, we were only applying the S3 CDN.
So all images stored locally, like the emojis, were never put on the local CDN.

Fixed a bunch of CookedPostProcessor test by adding a call to 'optimize_urls'
in order to get final URLs.

I also removed the unnecessary PrettyText.add_s3_cdn method since this is already
handled in the CookedPostProcessor.

lib/cooked_post_processor.rb

@@ -389,7 +389,7 @@ class CookedPostProcessor
     if upload
       thumbnail = upload.thumbnail(w, h)
       if thumbnail && thumbnail.filesize.to_i < upload.filesize
-        img["src"] = UrlHelper.cook_url(thumbnail.url)
+        img["src"] = thumbnail.url
 
         srcset = +""
 
@@ -408,11 +408,11 @@ class CookedPostProcessor
           img["srcset"] = "#{UrlHelper.cook_url(img["src"])}#{srcset}" if srcset.present?
         end
       else
-        img["src"] = UrlHelper.cook_url(upload.url)
+        img["src"] = upload.url
       end
 
       if small_upload = loading_image(upload)
-        img["data-small-upload"] = UrlHelper.cook_url(small_upload.url)
+        img["data-small-upload"] = small_upload.url
       end
     end
 
@@ -588,8 +588,10 @@ class CookedPostProcessor
       end
     end
 
-    @doc.css("img[src]").each do |img|
-      img["src"] = UrlHelper.cook_url(img["src"].to_s)
+    %w{src data-small-upload}.each do |selector|
+      @doc.css("img[#{selector}]").each do |img|
+        img[selector] = UrlHelper.cook_url(img[selector].to_s)
+      end
     end
   end
 

lib/file_store/local_store.rb

@@ -46,8 +46,7 @@ module FileStore
     end
 
     def cdn_url(url)
-      return url if Discourse.asset_host.blank?
-      url.sub(Discourse.base_url_no_prefix, Discourse.asset_host)
+      UrlHelper.local_cdn_url(url)
     end
 
     def path_for(upload)

lib/pretty_text.rb

@@ -254,10 +254,6 @@ module PrettyText
       add_rel_nofollow_to_user_content(doc)
     end
 
-    if SiteSetting.Upload.enable_s3_uploads && SiteSetting.Upload.s3_cdn_url.present?
-      add_s3_cdn(doc)
-    end
-
     if SiteSetting.enable_mentions
       add_mentions(doc, user_id: opts[:user_id])
     end
@@ -265,13 +261,6 @@ module PrettyText
     doc.to_html
   end
 
-  def self.add_s3_cdn(doc)
-    doc.css("img").each do |img|
-      next unless img["src"]
-      img["src"] = Discourse.store.cdn_url(img["src"])
-    end
-  end
-
   def self.add_rel_nofollow_to_user_content(doc)
     whitelist = []
 

lib/url_helper.rb

@@ -56,11 +56,20 @@ class UrlHelper
     no_cdn = SiteSetting.login_required || SiteSetting.prevent_anons_from_downloading_files
 
     url = absolute_without_cdn(url)
-    url = Discourse.store.cdn_url(url) unless is_attachment && no_cdn
+
+    unless is_attachment && no_cdn
+      url = Discourse.store.cdn_url(url)
+      url = local_cdn_url(url) if Discourse.store.external?
+    end
 
     schemaless(url)
   rescue URI::Error
     url
   end
 
+  def self.local_cdn_url(url)
+    return url if Discourse.asset_host.blank?
+    url.sub(Discourse.base_url_no_prefix, Discourse.asset_host)
+  end
+
 end