opensearch: autocomplete: Add opensearch compatibility

Add a parameter to autocomplete that enables opensearch-compatible
response format.

OpenSearch suggestions extension:
https://github.com/dewitt/opensearch/blob/master/mediawiki/Specifications/OpenSearch/Extensions/Suggestions/1.1/Draft%201.wiki

Author: fstachura

elixir/autocomplete.py

@@ -33,6 +33,7 @@ def on_get(self, req, resp):
         ident_prefix = req.get_param('q')
         family = req.get_param('f')
         project = req.get_param('p')
+        opensearch_mode = req.get_param('opensearch') == 'true'
 
         ident_prefix = validate_ident(ident_prefix)
         if ident_prefix is None:
@@ -82,7 +83,11 @@ def on_get(self, req, resp):
 
         resp.status = falcon.HTTP_200
         resp.content_type = falcon.MEDIA_JSON
-        resp.media = response
+
+        if not opensearch_mode:
+            resp.media = response
+        else:
+            resp.media = [ident_prefix, response]
 
         query.close()
 

static/search.xml

@@ -5,4 +5,5 @@
   <InputEncoding>UTF-8</InputEncoding>
   <Image width="16" height="16" type="image/x-icon">https://elixir.bootlin.com/static/favicon.ico</Image>
   <Url rel="results" type="text/html" template="https://elixir.bootlin.com/linux/latest/A/ident/{searchTerms}"/>
+  <Url rel="suggestions" type="application/x-suggestions+json" template="https://elixir.bootlin.com/acp?q={searchTerms}&amp;f=A&amp;p=linux&amp;opensearch=true"/>
 </OpenSearchDescription>