proxy: add Huawei (HMS) push type

Route push notifications to Huawei devices, which have no Google Play
Services and therefore cannot receive FCM. gorush, already used as the
push relay, supports HMS natively as platform 3.

HMS takes its payload as a serialized JSON string in "huawei_data" and
carries its own ttl/priority fields, so it needs its own branch rather
than the generic "data" object used for FCM and APNs.

The enum value is appended last: MSGPACK_ADD_ENUM serializes it as an
integer, so reordering would break compatibility with deployed proxies.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

src/dht_proxy_server.cpp

@@ -97,7 +97,7 @@ std::string
 DhtProxyServer::ServerStats::toString() const
 {
     auto ret = fmt::format("Listens: {}, Puts: {}, PushListeners: {}\n"
-                           "Push requests in the last {}: [Android: {}], [iOS: {}], [Unified: {}]\n"
+                           "Push requests in the last {}: [Android: {}], [iOS: {}], [Unified: {}], [Huawei: {}]\n"
                            "Requests: {} per second.",
                            listenCount,
                            putCount,
@@ -106,6 +106,7 @@ DhtProxyServer::ServerStats::toString() const
                            androidPush.toString(),
                            iosPush.toString(),
                            unifiedPush.toString(),
+                           huaweiPush.toString(),
                            requestRate);
     if (nodeInfo) {
         auto& ipv4 = nodeInfo->ipv4;
@@ -131,6 +132,7 @@ DhtProxyServer::ServerStats::toJson() const
     result["androidPush"] = androidPush.toJson();
     result["iosPush"] = iosPush.toJson();
     result["unifiedPush"] = unifiedPush.toJson();
+    result["huaweiPush"] = huaweiPush.toJson();
     result["requestRate"] = requestRate;
     if (nodeInfo)
         result["nodeInfo"] = nodeInfo->toJson();
@@ -639,6 +641,7 @@ DhtProxyServer::updateStats(std::shared_ptr<NodeInfo> info) const
         stats.androidPush = androidPush_;
         stats.iosPush = iosPush_;
         stats.unifiedPush = unifiedPush_;
+        stats.huaweiPush = huaweiPush_;
     }
 #endif
     stats.serverStartTime = serverStartTime_;
@@ -864,6 +867,8 @@ DhtProxyServer::getTypeFromString(const std::string& type)
         return PushType::iOS;
     else if (type == "unifiedpush")
         return PushType::UnifiedPush;
+    else if (type == "huawei")
+        return PushType::Huawei;
     return PushType::None;
 }
 
@@ -1275,15 +1280,25 @@ DhtProxyServer::sendPushNotification(
             Json::Value tokens(Json::arrayValue);
             tokens[0] = token;
             notification["tokens"] = std::move(tokens);
-            notification["platform"] = type == PushType::Android ? 2 : 1;
-            notification["data"] = std::move(json);
+            // gorush platform codes: 1 = iOS (APNs), 2 = Android (FCM), 3 = Huawei (HMS)
+            notification["platform"] = type == PushType::Android  ? 2
+                                       : type == PushType::Huawei ? 3
+                                                                  : 1;
             auto priority = highPriority ? "high" : "normal";
-            if (type == PushType::Android) {
+            if (type == PushType::Huawei) {
+                // HMS carries the payload as a serialized JSON string in its own field:
+                // the generic "data" object is ignored for this platform by gorush.
+                notification["huawei_data"] = Json::writeString(jsonBuilder_, json);
+                notification["huawei_ttl"] = "86400s"; // time to live = 24 hours
+                notification["priority"] = priority;
+            } else if (type == PushType::Android) {
+                notification["data"] = std::move(json);
                 Json::Value androidConfig(Json::objectValue);
                 androidConfig["priority"] = priority;
                 androidConfig["ttl"] = "86400s"; // time to live = 24 hours
                 notification["android"] = std::move(androidConfig);
             } else {
+                notification["data"] = std::move(json);
                 notification["priority"] = priority;
                 const auto expiration = std::chrono::system_clock::now() + std::chrono::hours(24);
                 uint32_t exp = std::chrono::duration_cast<std::chrono::seconds>(expiration.time_since_epoch()).count();
@@ -1336,6 +1351,9 @@ DhtProxyServer::sendPushNotification(
         case PushType::UnifiedPush:
             unifiedPush_.increment(highPriority);
             break;
+        case PushType::Huawei:
+            huaweiPush_.increment(highPriority);
+            break;
         default:
             break;
         }