config-policy: prioritize role from configuration file

The role defined in the endpoint-link configuration files must have higher
priority than the one set in the endpoint. If none of them are set, the config
policy fallbacks to the lowest one defined in the streams configuration file

modules/module-config-policy/config-policy.c

@@ -246,6 +246,34 @@ wp_config_policy_handle_endpoint (WpPolicy *policy, WpEndpoint *ep)
       WP_STREAM_ID_NONE, target, stream_id, data);
 }
 
+static const char *
+wp_config_policy_get_prioritized_stream (WpPolicy *policy,
+    const char *ep_stream, const char *te_stream, const char *te_streams)
+{
+  WpConfigPolicy *self = WP_CONFIG_POLICY (policy);
+
+  /* The target stream has higher priority than the endpoint stream */
+  const char *res = te_stream ? te_stream : ep_stream;
+  if (res)
+    return res;
+
+  /* If both streams are null, and no streams file is defined, return NULL */
+  if (!te_streams)
+    return NULL;
+
+  /* Otherwise get the lowest stream from streams */
+  g_autoptr (WpConfigParser) parser = NULL;
+  const struct WpParserStreamsData *streams = NULL;
+  const struct WpParserStreamsStreamData *lowest = NULL;
+  parser = wp_configuration_get_parser (self->config,
+      WP_PARSER_STREAMS_EXTENSION);
+  streams = wp_config_parser_get_matched_data (parser, (gpointer)te_streams);
+  if (!streams)
+    return NULL;
+  lowest = wp_parser_streams_get_lowest_stream (streams);
+  return lowest ? lowest->name : NULL;
+}
+
 static WpEndpoint *
 wp_config_policy_find_endpoint (WpPolicy *policy, GVariant *props,
     guint32 *stream_id)
@@ -258,7 +286,7 @@ wp_config_policy_find_endpoint (WpPolicy *policy, GVariant *props,
   WpEndpoint *target = NULL;
   g_autoptr (WpProxy) proxy = NULL;
   g_autoptr (WpProperties) p = NULL;
-  const char *role = NULL, *target_role = NULL;
+  const char *role = NULL;
 
   /* Get the data from props */
   g_variant_lookup (props, "data", "t", &data);
@@ -287,11 +315,15 @@ wp_config_policy_find_endpoint (WpPolicy *policy, GVariant *props,
 
   /* Set the stream id */
   if (stream_id) {
-    g_variant_lookup (props, "role", "&s", &role);
-    target_role = role ? role : data->te.stream;
-    *stream_id = target && target_role ?
-        wp_endpoint_find_stream (target, target_role) :
-        WP_CONTROL_ID_NONE;
+    if (target) {
+      g_variant_lookup (props, "role", "&s", &role);
+      const char *prioritized = wp_config_policy_get_prioritized_stream (policy,
+          role, data->te.stream, data->te.streams);
+      *stream_id = prioritized ? wp_endpoint_find_stream (target, prioritized) :
+          WP_STREAM_ID_NONE;
+    } else {
+      *stream_id = WP_STREAM_ID_NONE;
+    }
   }
 
   return g_object_ref (target);