#398

backend/app/services/preview/thumbnail_fetcher.rb

@@ -4,18 +4,15 @@ module Preview
 
     def self.fetch(raw_url)
       uri, = UrlSafety.validate(raw_url)
-      page = nil
 
       known_url = KnownSiteExtractor.thumbnail_url(uri)
-      image = fetch_image(known_url) if known_url
+      return fetch_image(known_url) if known_url
 
-      unless image
-        page = HttpFetcher.fetch(uri.to_s)
-        metadata = HtmlMetadataExtractor.extract(page)
-        image = fetch_image(metadata[:image_url]) if metadata[:image_url]
-      end
+      page = HttpFetcher.fetch(uri.to_s)
+      metadata = HtmlMetadataExtractor.extract(page)
+      raise GenerationFailed, 'サムネール画像が見つかりませんでした．' if metadata[:image_url].blank?
 
-      image || Screenshot.capture(uri.to_s)
+      fetch_image(metadata[:image_url])
     end
 
     def self.title(raw_url)
@@ -25,11 +22,15 @@ module Preview
 
     def self.fetch_image(url)
       response = HttpFetcher.fetch(url)
-      return unless response.content_type.downcase.start_with?('image/')
+      unless response.content_type.downcase.start_with?('image/')
+        raise GenerationFailed, 'サムネール画像が見つかりませんでした．'
+      end
 
       response.body
+    rescue HttpFetcher::FetchTimeout
+      raise
     rescue HttpFetcher::FetchFailed
-      nil
+      raise GenerationFailed, 'サムネール画像を取得できませんでした．'
     end
 
     private_class_method :fetch_image