Refactor: Move available_media_types to base class and compute once (#2640)

Move available_media_types method from Header to Base class and
compute it once during initialization instead of on each call.
This improves performance and code organization by moving shared
logic to the base class.

Co-authored-by: Daniel (dB.) Doubrovkine <[email protected]>

Author: ericproulx

CHANGELOG.md

@@ -5,6 +5,7 @@
 * [#2629](https://github.com/ruby-grape/grape/pull/2629): Refactor Router Architecture - [@ericproulx](https://github.com/ericproulx).
 * [#2633](https://github.com/ruby-grape/grape/pull/2633): Refactor API::Instance and reorganize DSL modules - [@ericproulx](https://github.com/ericproulx).
 * [#2636](https://github.com/ruby-grape/grape/pull/2636): Refactor router to simplify method signatures and reduce duplication - [@ericproulx](https://github.com/ericproulx).
+* [#2640](https://github.com/ruby-grape/grape/pull/2640): Compute available_media_types once - [@ericproulx](https://github.com/ericproulx).
 * [#2637](https://github.com/ruby-grape/grape/pull/2637): Refactor declared method - [@ericproulx](https://github.com/ericproulx).
 * [#2639](https://github.com/ruby-grape/grape/pull/2639): Refactor mime_types_for - [@ericproulx](https://github.com/ericproulx).
 * [#2638](https://github.com/ruby-grape/grape/pull/2638): Remove unnecessary path string duplication - [@ericproulx](https://github.com/ericproulx).

lib/grape/middleware/versioner/base.rb

@@ -50,6 +50,26 @@ def potential_version_match?(potential_version)
         def version_not_found!
           throw :error, status: 404, message: '404 API Version Not Found', headers: CASCADE_PASS_HEADER
         end
+
+        private
+
+        def available_media_types
+          @available_media_types ||= begin
+            media_types = []
+            base_media_type = "application/vnd.#{vendor}"
+            content_types.each_key do |extension|
+              versions&.reverse_each do |version|
+                media_types << "#{base_media_type}-#{version}+#{extension}"
+                media_types << "#{base_media_type}-#{version}"
+              end
+              media_types << "#{base_media_type}+#{extension}"
+            end
+
+            media_types << base_media_type
+            media_types.concat(content_types.values.flatten)
+            media_types
+          end
+        end
       end
     end
   end

lib/grape/middleware/versioner/header.rb

@@ -105,22 +105,6 @@ def version_not_found!(media_types)
 
           invalid_version_header!('API version not found.')
         end
-
-        def available_media_types
-          [].tap do |available_media_types|
-            base_media_type = "application/vnd.#{vendor}"
-            content_types.each_key do |extension|
-              versions&.reverse_each do |version|
-                available_media_types << "#{base_media_type}-#{version}+#{extension}"
-                available_media_types << "#{base_media_type}-#{version}"
-              end
-              available_media_types << "#{base_media_type}+#{extension}"
-            end
-
-            available_media_types << base_media_type
-            available_media_types.concat(content_types.values.flatten)
-          end
-        end
       end
     end
   end