make removeEffect send a packet

Make Potion immutable, and use long instead of Long

src/main/java/net/minestom/server/entity/Entity.java

@@ -405,7 +405,7 @@ public abstract class Entity implements Viewable, EventHandler, DataContainer, P
         // remove expired effects
         {
             effects.removeIf(timedPotion -> time >=
-                    (timedPotion.getStartingTime() + timedPotion.getPotion().duration * MinecraftServer.TICK_MS));
+                    (timedPotion.getStartingTime() + timedPotion.getPotion().getDuration() * MinecraftServer.TICK_MS));
         }
 
         // scheduled tasks
@@ -1464,7 +1464,13 @@ public abstract class Entity implements Viewable, EventHandler, DataContainer, P
      * @param effect The effect to remove
      */
     public void removeEffect(@NotNull PotionEffect effect) {
-        effects.removeIf(timedPotion -> timedPotion.getPotion().effect == effect);
+        effects.removeIf(timedPotion -> {
+            if (timedPotion.getPotion().getEffect() == effect) {
+                timedPotion.getPotion().sendRemovePacket(this);
+                return true;
+            }
+            return false;
+        });
     }
 
     /**
@@ -1473,7 +1479,7 @@ public abstract class Entity implements Viewable, EventHandler, DataContainer, P
      * @param potion The potion to add
      */
     public void addEffect(@NotNull Potion potion) {
-        removeEffect(potion.effect);
+        removeEffect(potion.getEffect());
         effects.add(new TimedPotion(potion, System.currentTimeMillis()));
         potion.sendAddPacket(this);
     }

src/main/java/net/minestom/server/network/packet/server/play/EntityEffectPacket.java

@@ -14,9 +14,9 @@ public class EntityEffectPacket implements ServerPacket {
     @Override
     public void write(@NotNull BinaryWriter writer) {
         writer.writeVarInt(entityId);
-        writer.writeByte((byte) potion.effect.getId());
-        writer.writeByte(potion.amplifier);
-        writer.writeVarInt(potion.duration);
+        writer.writeByte((byte) potion.getEffect().getId());
+        writer.writeByte(potion.getAmplifier());
+        writer.writeVarInt(potion.getDuration());
         writer.writeByte(potion.getFlags());
     }
 

src/main/java/net/minestom/server/potion/Potion.java

@@ -7,12 +7,10 @@ import net.minestom.server.network.packet.server.play.RemoveEntityEffectPacket;
 import org.jetbrains.annotations.NotNull;
 
 public class Potion {
-    public PotionEffect effect;
-    public byte amplifier;
-    public int duration;
-    public boolean ambient;
-    public boolean particles;
-    public boolean icon;
+    private final PotionEffect effect;
+    private final byte amplifier;
+    private final int duration;
+    private final byte flags;
 
     public Potion(PotionEffect effect, byte amplifier, int duration) {
         this(effect, amplifier, duration, true, true, false);
@@ -30,17 +28,27 @@ public class Potion {
         this.effect = effect;
         this.amplifier = amplifier;
         this.duration = duration;
-        this.particles = particles;
-        this.icon = icon;
-        this.ambient = ambient;
+        byte flags = 0;
+        if (ambient) flags = (byte)(flags | 0x01);
+        if (particles) flags = (byte)(flags | 0x02);
+        if (icon) flags = (byte)(flags | 0x04);
+        this.flags = flags;
+    }
+
+    public PotionEffect getEffect() {
+        return effect;
+    }
+
+    public byte getAmplifier() {
+        return amplifier;
+    }
+
+    public int getDuration() {
+        return duration;
     }
 
     public byte getFlags() {
-        byte computed = 0x00;
-        if (ambient) computed = (byte)(computed | 0x01);
-        if (particles) computed = (byte)(computed | 0x02);
-        if (icon) computed = (byte)(computed | 0x04);
-        return computed;
+        return flags;
     }
 
     public void sendAddPacket(@NotNull Entity entity) {

src/main/java/net/minestom/server/potion/TimedPotion.java

@@ -2,9 +2,9 @@ package net.minestom.server.potion;
 
 public class TimedPotion {
     private final Potion potion;
-    private final Long startingTime;
+    private final long startingTime;
 
-    public TimedPotion(Potion potion, Long startingTime) {
+    public TimedPotion(Potion potion, long startingTime) {
         this.potion = potion;
         this.startingTime = startingTime;
     }
@@ -13,7 +13,7 @@ public class TimedPotion {
         return potion;
     }
 
-    public Long getStartingTime() {
+    public long getStartingTime() {
         return startingTime;
     }
 }

src/test/java/demo/commands/PotionCommand.java

@@ -40,6 +40,7 @@ public class PotionCommand extends Command {
         final PotionEffect potion = args.getPotionEffect("potion");
         final int duration = args.getInteger("duration");
 
+        player.sendMessage(player.getActiveEffects().toString());
         player.addEffect(new Potion(
                 potion,
                 (byte) 0,