Merge pull request #176 from alphagov/publication-attachments

Turn `attachments` into `parts`

app/models/concerns/publishing_api/metadata.rb

@@ -114,6 +114,10 @@ def manual
     end
 
     def parts
+      parts_from_parts || parts_from_attachments
+    end
+
+    def parts_from_parts
       document_hash
         .dig(:details, :parts)
         &.map do
@@ -124,5 +128,29 @@ def parts
           }
         end
     end
+
+    def parts_from_attachments
+      document_hash
+        .dig(:details, :attachments)
+        &.map {
+          # Skip any attachments that aren't directly nested underneath this document
+          #
+          # This is replicated from v1 search-api behaviour, and is a workaround for the fact that
+          # the consumers always expect a slug rather than a URL, so parts cannot have a URL that
+          # doesn't match the document's base path.
+          next unless _1[:url].start_with?(document_hash[:base_path])
+
+          # The slug for a part from an attachment is the part of the URL that comes after the
+          # parent document's base path.
+          slug = _1[:url].sub(document_hash[:base_path], "").sub(%r{^/}, "").sub(%r{/$}, "")
+          {
+            slug:,
+            title: _1[:title],
+            # TODO: We don't receive any body content for attachments as part of the message from
+            # publishing-api. This needs to be fetched from publishing-api separately.
+            body: "",
+          }
+        }&.compact_blank
+    end
   end
 end