[traffic] Properly process message replacement

Signed-off-by: mvglasow <michael -at- vonglasow.com>

libs/map/traffic_manager.cpp

@@ -639,6 +639,13 @@ void TrafficManager::DecodeFirstMessage()
 
     // store message in cache
     m_messageCache.insert_or_assign(message.m_id, message);
+
+    for (auto & replaced : message.m_replaces)
+    {
+      auto it = m_messageCache.find(replaced);
+      if (it != m_messageCache.cend())
+        m_messageCache.erase(it);
+    }
   }
   /*
    * TODO detect if we can do a quick update:

libs/traffxml/traff_decoder.cpp

@@ -210,8 +210,14 @@ void TraffDecoder::DecodeMessage(traffxml::TraffMessage & message)
     return;
 
   traffxml::MultiMwmColoring decoded;
+  bool isDecoded = false;
 
-  auto it = m_messageCache.find(message.m_id);
+  std::vector<std::string> ids = message.m_replaces;
+  ids.insert(ids.begin(), message.m_id);
+
+  for (auto & id : ids)
+  {
+    auto it = m_messageCache.find(id);
     if ((it != m_messageCache.end())
         && !it->second.m_decoded.empty()
         && (it->second.m_location == message.m_location))
@@ -229,10 +235,18 @@ void TraffDecoder::DecodeMessage(traffxml::TraffMessage & message)
         message.m_decoded = it->second.m_decoded;
         return;
       }
-    else
+      else if (!isDecoded)
+      {
+        /*
+         * populate only on first occurrence but continue searching, we might find a matching
+         * location with matching impact
+         */
         decoded = it->second.m_decoded;
+        isDecoded = true;
       }
-  else
+    }
+  }
+  if (!isDecoded)
     DecodeLocation(message, decoded);
 
   if (impact)