Created a new packet for sending the last input tick to the server and deciding whether the player is afk or not.

src/main/java/dev/micle/loginprotection/network/client/LastInputTickPacket.java

@@ -0,0 +1,59 @@
+package dev.micle.loginprotection.network.client;
+
+import dev.micle.loginprotection.data.ProtectedPlayer;
+import dev.micle.loginprotection.data.ProtectedPlayerManager;
+import dev.micle.loginprotection.network.NetworkManager;
+import dev.micle.loginprotection.proxy.Proxy;
+import dev.micle.loginprotection.setup.Config;
+import net.minecraft.network.FriendlyByteBuf;
+import net.minecraft.server.level.ServerPlayer;
+import net.minecraftforge.network.NetworkEvent;
+
+import java.util.function.Supplier;
+
+public class LastInputTickPacket {
+    private final int lastInputTick;
+
+    public LastInputTickPacket() {
+        this(Proxy.Client.getLastInputTick());
+    }
+    public LastInputTickPacket(int lastInputTick) {
+        this.lastInputTick = lastInputTick;
+    }
+
+    public static void encode(final LastInputTickPacket packet, final FriendlyByteBuf buffer) {
+        NetworkManager.writeVersionInfo(buffer, false);
+        buffer.writeInt(packet.lastInputTick);
+    }
+
+    public static LastInputTickPacket decode(final FriendlyByteBuf buffer) {
+        NetworkManager.checkVersion(buffer);
+        return new LastInputTickPacket(buffer.readInt());
+    }
+
+    public static void handle(final LastInputTickPacket packet, final Supplier<NetworkEvent.Context> contextSupplier) {
+        final NetworkEvent.Context context = contextSupplier.get();
+        context.enqueueWork(() -> {
+            // Get sender
+            ServerPlayer sender = context.getSender();
+            if (sender == null) {
+                return;
+            }
+
+            // Get protected player
+            ProtectedPlayer protectedPlayer = ProtectedPlayerManager.getPlayer(sender.getUUID());
+            if (protectedPlayer == null) {
+                return;
+            }
+
+            // Check if player is afk
+            if (sender.tickCount - packet.lastInputTick >= Config.Server.AFK_TIME_THRESHOLD.get() * 20) {
+                ProtectedPlayerManager.updateState(sender.getUUID()); // Update state
+            } else {
+                ProtectedPlayerManager.startAfkTimer(sender.getUUID(), (long) ((Config.Server.AFK_TIME_THRESHOLD.get() -
+                                        ((sender.tickCount - packet.lastInputTick) / 20.0)) * 1000)); // Start new afk timer
+            }
+        });
+        context.setPacketHandled(true);
+    }
+}