Disable no swing check for 1.8 clients on modern servers

src/main/java/ac/grim/grimac/checks/impl/badpackets/BadPacketsH.java

@@ -4,13 +4,20 @@
 import ac.grim.grimac.checks.CheckData;
 import ac.grim.grimac.checks.type.PacketCheck;
 import ac.grim.grimac.player.GrimPlayer;
+import com.github.retrooper.packetevents.PacketEvents;
 import com.github.retrooper.packetevents.event.PacketReceiveEvent;
+import com.github.retrooper.packetevents.manager.server.ServerVersion;
 import com.github.retrooper.packetevents.protocol.packettype.PacketType;
 import com.github.retrooper.packetevents.protocol.player.ClientVersion;
 import com.github.retrooper.packetevents.wrapper.play.client.WrapperPlayClientInteractEntity;
+import com.github.retrooper.packetevents.wrapper.play.client.WrapperPlayClientPlayerFlying;
 
 @CheckData(name = "BadPacketsH")
 public class BadPacketsH extends Check implements PacketCheck {
+
+    // 1.9 packet order: INTERACT -> ANIMATION
+    // 1.8 packet order: ANIMATION -> INTERACT
+    // I personally think 1.8 made much more sense. You swing and THEN you hit!
     private boolean sentAnimation = player.getClientVersion().isNewerThan(ClientVersion.V_1_8);
 
     public BadPacketsH(final GrimPlayer player) {
@@ -24,6 +31,19 @@ public void onPacketReceive(PacketReceiveEvent event) {
         } else if (event.getPacketType() == PacketType.Play.Client.INTERACT_ENTITY) {
             WrapperPlayClientInteractEntity packet = new WrapperPlayClientInteractEntity(event);
             if (packet.getAction() != WrapperPlayClientInteractEntity.InteractAction.ATTACK) return;
+
+            // There is a "bug" in ViaRewind
+            // 1.8 packet order: ANIMATION -> INTERACT
+            // 1.9 packet order: INTERACT -> ANIMATION
+            // ViaRewind, on 1.9+ servers, delays a 1.8 client's ANIMATION to be after INTERACT (but before flying).
+            // Which means we see 1.9 packet order for 1.8 clients
+            // Due to ViaRewind also delaying the swings, we then see packet order above 20CPS like:
+            // INTERACT -> INTERACT -> ANIMATION -> ANIMATION
+            // I will simply disable this check for 1.8- clients on 1.9+ servers as I can't be bothered to find a way around this.
+            // Stop supporting such old clients on modern servers!
+            if (player.getClientVersion().isOlderThan(ClientVersion.V_1_9)
+                    && PacketEvents.getAPI().getServerManager().getVersion().isNewerThan(ServerVersion.V_1_8)) return;
+
             if (!sentAnimation && flagAndAlert()) {
                 event.setCancelled(true);
                 player.onPacketCancel();