Add basic support for remote attachments with multiple media types (#34996)

app/helpers/json_ld_helper.rb

@@ -26,6 +26,8 @@ module JsonLdHelper
   # The url attribute can be a string, an array of strings, or an array of objects.
   # The objects could include a mimeType. Not-included mimeType means it's text/html.
   def url_to_href(value, preferred_type = nil)
+    value = [value] if value.is_a?(Hash)
+
     single_value = if value.is_a?(Array) && !value.first.is_a?(String)
                      value.find { |link| preferred_type.nil? || ((link['mimeType'].presence || 'text/html') == preferred_type) }
                    elsif value.is_a?(Array)
@@ -41,6 +43,15 @@ module JsonLdHelper
     end
   end
 
+  def url_to_media_type(value, preferred_type = nil)
+    value = [value] if value.is_a?(Hash)
+    return unless value.is_a?(Array) && !value.first.is_a?(String)
+
+    single_value = value.find { |link| preferred_type.nil? || ((link['mimeType'].presence || 'text/html') == preferred_type) }
+
+    single_value['mediaType'] unless single_value.nil?
+  end
+
   def as_array(value)
     if value.nil?
       []

app/lib/activitypub/parser/media_attachment_parser.rb

@@ -15,7 +15,7 @@ class ActivityPub::Parser::MediaAttachmentParser
   end
 
   def remote_url
-    url = Addressable::URI.parse(@json['url'])&.normalize&.to_s
+    url = Addressable::URI.parse(url_to_href(@json['url']))&.normalize&.to_s
     url unless unsupported_uri_scheme?(url)
   rescue Addressable::URI::InvalidURIError
     nil
@@ -43,7 +43,7 @@ class ActivityPub::Parser::MediaAttachmentParser
   end
 
   def file_content_type
-    @json['mediaType']
+    @json['mediaType'] || url_to_media_type(@json['url'])
   end
 
   private