support dedicated image servers

app/models/amazon_backup.rb

@@ -1,3 +1,5 @@
+# donmai.us specific
+
 require 'base64'
 require 'digest/md5'
 

app/models/post.rb

@@ -145,29 +145,16 @@ class Post < ApplicationRecord
     end
 
     def file_url
-       if Danbooru.config.use_s3_proxy?(self)
-         "/cached/data/#{seo_tag_string}#{file_path_prefix}#{md5}.#{file_ext}"
-       else
-         "/data/#{seo_tag_string}#{file_path_prefix}#{md5}.#{file_ext}"
-       end
+      "#{Danbooru.config.image_server_host(self)}/data/#{seo_tag_string}#{file_path_prefix}#{md5}.#{file_ext}"
     end
 
     # this is for the 640x320 version
     def cropped_file_url
-      if Danbooru.config.use_s3_proxy?(self)
-        "/cached/data/cropped/large/#{md5}.jpg"
-      else
-        "/data/cropped/large/#{md5}.jpg"
-      end
     end
 
     def large_file_url
       if has_large?
-        if Danbooru.config.use_s3_proxy?(self)
-          "/cached/data/sample/#{seo_tag_string}#{file_path_prefix}#{Danbooru.config.large_image_prefix}#{md5}.#{large_file_ext}"
-        else
-          "/data/sample/#{seo_tag_string}#{file_path_prefix}#{Danbooru.config.large_image_prefix}#{md5}.#{large_file_ext}"
-        end
+        "#{Danbooru.config.image_server_host(self)}/data/sample/#{seo_tag_string}#{file_path_prefix}#{Danbooru.config.large_image_prefix}#{md5}.#{large_file_ext}"
       else
         file_url
       end
@@ -190,11 +177,7 @@ class Post < ApplicationRecord
         return "/images/download-preview.png"
       end
 
-      # if has_cropped? && !CurrentUser.disable_cropped_thumbnails?
-      #   "/cached/data/cropped/small/#{md5}.jpg"
-      # else
-        "/data/preview/#{file_path_prefix}#{md5}.jpg"
-      # end
+      "/data/preview/#{file_path_prefix}#{md5}.jpg"
     end
 
     def complete_preview_file_url
@@ -204,9 +187,17 @@ class Post < ApplicationRecord
     def open_graph_image_url
       if is_image?
         if has_large?
-          "http://#{Danbooru.config.hostname}#{large_file_url}"
+          if Danbooru.config.image_server_host(self) =~ /http/
+            large_file_url
+          else
+            "http://#{Danbooru.config.hostname}#{large_file_url}"
+          end
         else
-          "http://#{Danbooru.config.hostname}#{file_url}"
+          if Danbooru.config.image_server_host(self) =~ /http/
+            file_url
+          else
+            "http://#{Danbooru.config.hostname}#{file_url}"
+          end
         end
       else
         complete_preview_file_url