Changed grace period time from 200 to 400 (5s to 10s). Added function to ProtectedPlayers.java to remove a player from the list, updated the updateGracePeriods method. Updated C2SKeyPress.java. Made OnKeyPressEventHandler.java check for mouse clicks as well, also made sure it only fires on client-side. Added an event for when a player leaves the server to remove them from the list.

src/main/java/com/micle/loginprotection/LoginProtection.java

@@ -3,8 +3,11 @@ package com.micle.loginprotection;
 import com.micle.loginprotection.data.ProtectedPlayer;
 import com.micle.loginprotection.data.ProtectedPlayers;
 import com.micle.loginprotection.setup.Registration;
+import net.minecraft.util.ResourceLocation;
 import net.minecraftforge.common.MinecraftForge;
 import net.minecraftforge.fml.common.Mod;
+import net.minecraftforge.fml.network.NetworkRegistry;
+import net.minecraftforge.fml.network.simple.SimpleChannel;
 
 import java.util.ArrayList;
 import java.util.List;
@@ -15,6 +18,14 @@ public class LoginProtection {
     public static ProtectedPlayers protected_players = new ProtectedPlayers();
     public static boolean has_pressed_key = false;
 
+    private static final String PROTOCOL_VERSION = "1";
+    public static final SimpleChannel INSTANCE = NetworkRegistry.newSimpleChannel(
+            new ResourceLocation(LoginProtection.MOD_ID, "main"),
+            () -> PROTOCOL_VERSION,
+            PROTOCOL_VERSION::equals,
+            PROTOCOL_VERSION::equals
+    );
+
     public LoginProtection() {
         Registration.register();
 

src/main/java/com/micle/loginprotection/data/ProtectedPlayer.java

@@ -9,7 +9,7 @@ public class ProtectedPlayer {
 
     public ProtectedPlayer(UUID player_uuid) {
         this.player_uuid = player_uuid;
-        this.grace_period = 200;
+        this.grace_period = 400;
         this.is_loading = true;
     }
 

src/main/java/com/micle/loginprotection/data/ProtectedPlayers.java

@@ -1,5 +1,13 @@
 package com.micle.loginprotection.data;
 
+import net.minecraft.entity.ai.attributes.Attribute;
+import net.minecraft.entity.ai.attributes.Attributes;
+import net.minecraft.entity.player.ServerPlayerEntity;
+import net.minecraft.potion.EffectInstance;
+import net.minecraft.potion.Effects;
+import net.minecraft.util.text.StringTextComponent;
+import net.minecraftforge.fml.server.ServerLifecycleHooks;
+
 import java.util.ArrayList;
 import java.util.List;
 import java.util.UUID;
@@ -29,18 +37,25 @@ public class ProtectedPlayers {
     }
 
     public void removePlayer(UUID player_uuid) {
-        ProtectedPlayer player = getPlayer(player_uuid);
+        ProtectedPlayer protected_player = getPlayer(player_uuid);
+        if (protected_player == null) { return; }
+        protected_players.remove(protected_player);
+
+        ServerPlayerEntity player = ServerLifecycleHooks.getCurrentServer().getPlayerList().getPlayer(player_uuid);
         if (player == null) { return; }
-        protected_players.remove(player);
+        player.sendMessage(new StringTextComponent("Grace Period over!"), player_uuid);
     }
 
     public void updateGracePeriods() {
         for (ProtectedPlayer protected_player : protected_players) {
-            if (protected_player.isLoading() || protected_player.getGracePeriod() <= 0) { continue; }
+            if (protected_player.isLoading()) { continue; }
-            int grace_period = protected_player.getGracePeriod();
+
-            protected_player.setGracePeriod(grace_period-1);
+            int grace_period = protected_player.getGracePeriod()-1;
+            protected_player.setGracePeriod(grace_period);
             if (grace_period <= 0) {
                 removePlayer(protected_player.getPlayerUUID());
+                System.out.println(protected_player.getPlayerUUID() + " is no longer being protected!");
+                break;
             }
         }
     }

src/main/java/com/micle/loginprotection/events/OnKeyPressEventHandler.java

@@ -1,13 +1,28 @@
 package com.micle.loginprotection.events;
 
 import com.micle.loginprotection.LoginProtection;
+import com.micle.loginprotection.network.C2SKeyPress;
+import net.minecraft.client.Minecraft;
+import net.minecraft.client.multiplayer.ServerData;
+import net.minecraftforge.api.distmarker.Dist;
+import net.minecraftforge.api.distmarker.OnlyIn;
 import net.minecraftforge.client.event.InputEvent;
 import net.minecraftforge.eventbus.api.SubscribeEvent;
 
 public class OnKeyPressEventHandler {
     @SubscribeEvent
+    @OnlyIn(Dist.CLIENT)
     public void KeyPressEvent(InputEvent.KeyInputEvent event) {
-        if (LoginProtection.has_pressed_key) { return; }
+        ServerData server = Minecraft.getInstance().getCurrentServer();
+        if (server == null) { return; }
+        LoginProtection.INSTANCE.sendToServer(new C2SKeyPress());
+    }
 
+    @SubscribeEvent
+    @OnlyIn(Dist.CLIENT)
+    public void MouseClickEvent(InputEvent.ClickInputEvent event) {
+        ServerData server = Minecraft.getInstance().getCurrentServer();
+        if (server == null) { return; }
+        LoginProtection.INSTANCE.sendToServer(new C2SKeyPress());
     }
 }

src/main/java/com/micle/loginprotection/events/OnPlayerJoinEventHandler.java

@@ -5,14 +5,16 @@ import com.micle.loginprotection.data.ProtectedPlayer;
 import net.minecraft.entity.LivingEntity;
 import net.minecraft.entity.player.PlayerEntity;
 import net.minecraftforge.event.entity.EntityJoinWorldEvent;
+import net.minecraftforge.event.entity.player.PlayerEvent;
 import net.minecraftforge.eventbus.api.SubscribeEvent;
 
 public class OnPlayerJoinEventHandler {
     @SubscribeEvent
-    public void EntityJoinWorldEvent(EntityJoinWorldEvent event) {
+    public void EntityJoinWorldEvent(PlayerEvent.PlayerLoggedInEvent event) {
         if (!(event.getEntity() instanceof PlayerEntity)) { return; }
         PlayerEntity player = (PlayerEntity) event.getEntity();
 
         LoginProtection.protected_players.addPlayer(player.getUUID());
+        System.out.println(player.getUUID() + " (" + player.getDisplayName().getString() + ") is being protected!");
     }
 }

src/main/java/com/micle/loginprotection/events/OnPlayerLeaveEventHandler.java

@@ -0,0 +1,19 @@
+package com.micle.loginprotection.events;
+
+import com.micle.loginprotection.LoginProtection;
+import net.minecraft.entity.player.PlayerEntity;
+import net.minecraftforge.api.distmarker.Dist;
+import net.minecraftforge.api.distmarker.OnlyIn;
+import net.minecraftforge.event.entity.player.PlayerEvent;
+import net.minecraftforge.eventbus.api.SubscribeEvent;
+
+public class OnPlayerLeaveEventHandler {
+    @SubscribeEvent
+    @OnlyIn(Dist.DEDICATED_SERVER)
+    public void PlayerLeaveEvent(PlayerEvent.PlayerLoggedOutEvent event) {
+        if (!(event.getEntity() instanceof PlayerEntity)) { return; }
+        PlayerEntity player = event.getPlayer();
+
+        LoginProtection.protected_players.removePlayer(player.getUUID());
+    }
+}

src/main/java/com/micle/loginprotection/events/OnServerTickEventHandler.java

@@ -7,8 +7,6 @@ import net.minecraftforge.eventbus.api.SubscribeEvent;
 public class OnServerTickEventHandler {
     @SubscribeEvent
     public void ServerTickEvent(TickEvent.ServerTickEvent event) {
-        if (LoginProtection.protected_players.size() == 0) { return; }
-
         LoginProtection.protected_players.updateGracePeriods();
     }
 }

src/main/java/com/micle/loginprotection/network/C2SKeyPress.java

@@ -3,7 +3,10 @@ package com.micle.loginprotection.network;
 import com.micle.loginprotection.LoginProtection;
 import net.minecraft.entity.player.ServerPlayerEntity;
 import net.minecraft.network.PacketBuffer;
+import net.minecraft.util.text.StringTextComponent;
+import net.minecraftforge.fml.network.NetworkDirection;
 import net.minecraftforge.fml.network.NetworkEvent;
+import net.minecraftforge.fml.network.PacketDistributor;
 
 import java.util.function.Supplier;
 
@@ -21,8 +24,14 @@ public class C2SKeyPress {
         context.enqueueWork(() -> {
             final ServerPlayerEntity sender = context.getSender();
             if (sender == null) { return; }
+            if (LoginProtection.protected_players.getPlayer(sender.getUUID()) == null) { return; }
+            if (!LoginProtection.protected_players.getPlayer(sender.getUUID()).isLoading()) { return; }
 
             LoginProtection.protected_players.getPlayer(sender.getUUID()).setLoading(false);
+            sender.sendMessage(new StringTextComponent("Grace Period started!"), sender.getUUID());
+            if (sender.isInWater()) {
+                sender.setAirSupply(sender.getMaxAirSupply());
+            }
         });
         context.setPacketHandled(true);
     }

src/main/java/com/micle/loginprotection/setup/Registration.java

@@ -1,33 +1,24 @@
 package com.micle.loginprotection.setup;
 
 import com.micle.loginprotection.LoginProtection;
-import com.micle.loginprotection.events.OnPlayerDamageEventHandler;
+import com.micle.loginprotection.events.*;
-import com.micle.loginprotection.events.OnPlayerJoinEventHandler;
 import com.micle.loginprotection.network.C2SKeyPress;
-import net.minecraft.util.ResourceLocation;
 import net.minecraftforge.common.MinecraftForge;
 import net.minecraftforge.eventbus.api.IEventBus;
 import net.minecraftforge.fml.javafmlmod.FMLJavaModLoadingContext;
-import net.minecraftforge.fml.network.NetworkRegistry;
-import net.minecraftforge.fml.network.simple.SimpleChannel;
 
 public class Registration {
-    private static final String PROTOCOL_VERSION = "1";
-    public static final SimpleChannel INSTANCE = NetworkRegistry.newSimpleChannel(
-            new ResourceLocation(LoginProtection.MOD_ID, "main"),
-            () -> PROTOCOL_VERSION,
-            PROTOCOL_VERSION::equals,
-            PROTOCOL_VERSION::equals
-    );
-
     public static void register() {
         IEventBus mod_event_bus = FMLJavaModLoadingContext.get().getModEventBus();
 
         MinecraftForge.EVENT_BUS.register(new OnPlayerJoinEventHandler());
         MinecraftForge.EVENT_BUS.register(new OnPlayerDamageEventHandler());
+        MinecraftForge.EVENT_BUS.register(new OnServerTickEventHandler());
+        MinecraftForge.EVENT_BUS.register(new OnKeyPressEventHandler());
+        MinecraftForge.EVENT_BUS.register(new OnPlayerLeaveEventHandler());
 
         int id = 0;
-        INSTANCE.registerMessage(id++,
+        LoginProtection.INSTANCE.registerMessage(id++,
                 C2SKeyPress.class,
                 C2SKeyPress::encode,
                 C2SKeyPress::decode,