#399

backend/app/services/post_thumbnail_upload_validator.rb

@@ -0,0 +1,18 @@
+class PostThumbnailUploadValidator
+  MAX_THUMBNAIL_BYTES = 20 * 1024 * 1024
+
+  class InvalidUpload < StandardError; end
+
+  def self.validate! thumbnail
+    return if thumbnail.blank?
+    raise InvalidUpload, 'thumbnail upload が不正です．' unless thumbnail.is_a?(ActionDispatch::Http::UploadedFile)
+    raise InvalidUpload, 'thumbnail file size が大きすぎます．' if thumbnail.size > MAX_THUMBNAIL_BYTES
+
+    attachment = Post.resized_thumbnail_attachment(thumbnail)
+    attachment[:io].close if attachment[:io].respond_to?(:close)
+  rescue MiniMagick::Error
+    raise InvalidUpload, 'サムネイル画像の変換に失敗しました．'
+  ensure
+    thumbnail&.rewind if thumbnail.respond_to?(:rewind)
+  end
+end