plugin/src/main/java/lol/pyr/znpcsplus/commands/property/PropertySetCommand.java

@@ -11,6 +11,7 @@ import lol.pyr.director.adventure.command.CommandHandler;
 import lol.pyr.director.common.command.CommandExecutionException;
 import lol.pyr.znpcsplus.api.entity.EntityProperty;
 import lol.pyr.znpcsplus.entity.EntityPropertyImpl;
+import lol.pyr.znpcsplus.entity.properties.attributes.AttributeProperty;
 import lol.pyr.znpcsplus.npc.NpcEntryImpl;
 import lol.pyr.znpcsplus.npc.NpcImpl;
 import lol.pyr.znpcsplus.npc.NpcRegistryImpl;
@@ -124,6 +125,15 @@ public class PropertySetCommand implements CommandHandler {
             value = context.parse(type);
             valueName = value == null ? "NONE" : ((Vector3i) value).toPrettyString();
         }
+        else if (property instanceof AttributeProperty) {
+            value = context.parse(type);
+            if ((double) value < ((AttributeProperty) property).getMinValue() || (double) value > ((AttributeProperty) property).getMaxValue()) {
+                double sanitizedValue = ((AttributeProperty) property).sanitizeValue((double) value);
+                context.send(Component.text("WARNING: Value " + value + " is out of range for property " + property.getName() + ", setting to " + sanitizedValue, NamedTextColor.YELLOW));
+                value = sanitizedValue;
+            }
+            valueName = String.valueOf(value);
+        }
         else {
             try {
                 value = context.parse(type);

plugin/src/main/java/lol/pyr/znpcsplus/entity/EntityPropertyRegistryImpl.java

@@ -2,6 +2,7 @@ package lol.pyr.znpcsplus.entity;
 
 import com.github.retrooper.packetevents.PacketEvents;
 import com.github.retrooper.packetevents.manager.server.ServerVersion;
+import com.github.retrooper.packetevents.protocol.attribute.Attributes;
 import com.github.retrooper.packetevents.protocol.entity.data.EntityDataTypes;
 import com.github.retrooper.packetevents.protocol.entity.pose.EntityPose;
 import com.github.retrooper.packetevents.protocol.nbt.NBTCompound;
@@ -15,6 +16,7 @@ import lol.pyr.znpcsplus.api.entity.EntityPropertyRegistry;
 import lol.pyr.znpcsplus.api.skin.SkinDescriptor;
 import lol.pyr.znpcsplus.config.ConfigManager;
 import lol.pyr.znpcsplus.entity.properties.*;
+import lol.pyr.znpcsplus.entity.properties.attributes.AttributeProperty;
 import lol.pyr.znpcsplus.entity.properties.villager.VillagerLevelProperty;
 import lol.pyr.znpcsplus.entity.properties.villager.VillagerProfessionProperty;
 import lol.pyr.znpcsplus.entity.properties.villager.VillagerTypeProperty;
@@ -154,6 +156,16 @@ public class EntityPropertyRegistryImpl implements EntityPropertyRegistry {
         linkProperties("glow", "fire", "invisible");
         register(new BooleanProperty("silent", 4, false, legacyBooleans));
 
+        // Attribute Max Health
+        register(new AttributeProperty(packetFactory, "attribute_max_health", Attributes.MAX_HEALTH));
+
+        // Health - LivingEntity
+        int healthIndex = 6;
+        if (ver.isNewerThanOrEquals(ServerVersion.V_1_17)) healthIndex = 9;
+        else if (ver.isNewerThanOrEquals(ServerVersion.V_1_14)) healthIndex = 8;
+        else if (ver.isNewerThanOrEquals(ServerVersion.V_1_10)) healthIndex = 7;
+        register(new HealthProperty(healthIndex));
+
         final int tameableIndex;
         if (ver.isNewerThanOrEquals(ServerVersion.V_1_17)) tameableIndex = 17;
         else if (ver.isNewerThanOrEquals(ServerVersion.V_1_15)) tameableIndex = 16;

plugin/src/main/java/lol/pyr/znpcsplus/entity/properties/HealthProperty.java

@@ -0,0 +1,27 @@
+package lol.pyr.znpcsplus.entity.properties;
+
+import com.github.retrooper.packetevents.protocol.attribute.Attributes;
+import com.github.retrooper.packetevents.protocol.entity.data.EntityData;
+import com.github.retrooper.packetevents.protocol.entity.data.EntityDataTypes;
+import lol.pyr.znpcsplus.entity.EntityPropertyImpl;
+import lol.pyr.znpcsplus.entity.PacketEntity;
+import org.bukkit.entity.Player;
+
+import java.util.Map;
+
+public class HealthProperty extends EntityPropertyImpl<Float> {
+    private final int index;
+
+    public HealthProperty(int index) {
+        super("health", 20f, Float.class);
+        this.index = index;
+    }
+
+    @Override
+    public void apply(Player player, PacketEntity entity, boolean isSpawned, Map<Integer, EntityData> properties) {
+        float health = entity.getProperty(this);
+        health = (float) Attributes.MAX_HEALTH.sanitizeValue(health);
+        properties.put(index, new EntityData(index, EntityDataTypes.FLOAT, health));
+
+    }
+}

plugin/src/main/java/lol/pyr/znpcsplus/entity/properties/attributes/AttributeProperty.java

@@ -0,0 +1,63 @@
+package lol.pyr.znpcsplus.entity.properties.attributes;
+
+import com.github.retrooper.packetevents.protocol.attribute.Attribute;
+import com.github.retrooper.packetevents.protocol.entity.data.EntityData;
+import com.github.retrooper.packetevents.wrapper.play.server.WrapperPlayServerUpdateAttributes;
+import lol.pyr.znpcsplus.entity.EntityPropertyImpl;
+import lol.pyr.znpcsplus.entity.PacketEntity;
+import lol.pyr.znpcsplus.packets.PacketFactory;
+import org.bukkit.entity.Player;
+
+import java.util.Collections;
+import java.util.List;
+import java.util.Map;
+
+public class AttributeProperty extends EntityPropertyImpl<Double> {
+    private final PacketFactory packetFactory;
+    private final Attribute attribute;
+
+    public AttributeProperty(PacketFactory packetFactory, String name, Attribute attribute) {
+        super(name, attribute.getDefaultValue(), Double.class);
+        this.packetFactory = packetFactory;
+        this.attribute = attribute;
+    }
+
+    public double getMinValue() {
+        return attribute.getMinValue();
+    }
+
+    public double getMaxValue() {
+        return attribute.getMaxValue();
+    }
+
+    public double sanitizeValue(double value) {
+        return attribute.sanitizeValue(value);
+    }
+
+    @Override
+    public List<EntityData> applyStandalone(Player player, PacketEntity packetEntity, boolean isSpawned) {
+        apply(player, packetEntity, isSpawned, Collections.emptyList());
+        return Collections.emptyList();
+    }
+
+    @Override
+    public void apply(Player player, PacketEntity entity, boolean isSpawned, Map<Integer, EntityData> properties) {
+    }
+
+    public void apply(Player player, PacketEntity entity, boolean isSpawned, List<WrapperPlayServerUpdateAttributes.Property> properties) {
+        Double value = entity.getProperty(this);
+        if (value == null) {
+            return;
+        }
+        value = attribute.sanitizeValue(value);
+        if (isSpawned) {
+            packetFactory.sendAttribute(player, entity, new WrapperPlayServerUpdateAttributes.Property(attribute, value, Collections.emptyList()));
+        } else {
+            properties.add(new WrapperPlayServerUpdateAttributes.Property(attribute, value, Collections.emptyList()));
+        }
+    }
+
+    public Attribute getAttribute() {
+        return attribute;
+    }
+}

plugin/src/main/java/lol/pyr/znpcsplus/npc/NpcTypeImpl.java

@@ -120,6 +120,9 @@ public class NpcTypeImpl implements NpcType {
                     "player_knockback_horizontal", "player_knockback_cooldown", "player_knockback_sound", "player_knockback_sound_name",
                     "player_knockback_sound_volume", "player_knockback_sound_pitch");
             if (!type.equals(EntityTypes.PLAYER)) addProperties("dinnerbone");
+            if (EntityTypes.isTypeInstanceOf(type, EntityTypes.LIVINGENTITY)) {
+                addProperties("health", "attribute_max_health");
+            }
             // TODO: make this look nicer after completing the rest of the properties
             if (version.isNewerThanOrEquals(ServerVersion.V_1_9)) addProperties("glow");
             if (version.isNewerThanOrEquals(ServerVersion.V_1_14)) {

plugin/src/main/java/lol/pyr/znpcsplus/packets/PacketFactory.java

@@ -2,6 +2,7 @@ package lol.pyr.znpcsplus.packets;
 
 import com.github.retrooper.packetevents.protocol.entity.data.EntityData;
 import com.github.retrooper.packetevents.protocol.player.Equipment;
+import com.github.retrooper.packetevents.wrapper.play.server.WrapperPlayServerUpdateAttributes;
 import lol.pyr.znpcsplus.api.entity.PropertyHolder;
 import lol.pyr.znpcsplus.entity.PacketEntity;
 import lol.pyr.znpcsplus.util.NamedColor;
@@ -25,4 +26,6 @@ public interface PacketFactory {
     void sendHeadRotation(Player player, PacketEntity entity, float yaw, float pitch);
     void sendHandSwing(Player player, PacketEntity entity, boolean offHand);
     void setPassengers(Player player, int vehicle, int... passengers);
+    void sendAllAttributes(Player player, PacketEntity entity, PropertyHolder properties);
+    void sendAttribute(Player player, PacketEntity entity, WrapperPlayServerUpdateAttributes.Property property);
 }

plugin/src/main/java/lol/pyr/znpcsplus/packets/V1_17PacketFactory.java

@@ -1,6 +1,7 @@
 package lol.pyr.znpcsplus.packets;
 
 import com.github.retrooper.packetevents.PacketEventsAPI;
+import com.github.retrooper.packetevents.protocol.entity.type.EntityTypes;
 import com.github.retrooper.packetevents.util.Vector3d;
 import com.github.retrooper.packetevents.wrapper.play.server.WrapperPlayServerSpawnEntity;
 import lol.pyr.znpcsplus.api.entity.PropertyHolder;
@@ -27,6 +28,7 @@ public class V1_17PacketFactory extends V1_8PacketFactory {
         sendPacket(player, new WrapperPlayServerSpawnEntity(entity.getEntityId(), Optional.of(entity.getUuid()), entity.getType(),
                 npcLocationToVector(location), location.getPitch(), location.getYaw(), location.getYaw(), 0, Optional.of(new Vector3d())));
         sendAllMetadata(player, entity, properties);
+        if (EntityTypes.isTypeInstanceOf(entity.getType(), EntityTypes.LIVINGENTITY)) sendAllAttributes(player, entity, properties);
         createTeam(player, entity, properties.getProperty(propertyRegistry.getByName("glow", NamedColor.class)));
     }
 }

plugin/src/main/java/lol/pyr/znpcsplus/packets/V1_20_2PacketFactory.java

@@ -36,6 +36,7 @@ public class V1_20_2PacketFactory extends V1_19_3PacketFactory {
                     npcLocationToVector(location), location.getPitch(), location.getYaw(), location.getYaw(), 0, Optional.of(new Vector3d())));
             sendPacket(player, new WrapperPlayServerEntityHeadLook(entity.getEntityId(), location.getYaw()));
             sendAllMetadata(player, entity, properties);
+            sendAllAttributes(player, entity, properties);
             scheduler.runLaterAsync(() -> removeTabPlayer(player, entity), configManager.getConfig().tabHideDelay());
         });
     }

plugin/src/main/java/lol/pyr/znpcsplus/packets/V1_8PacketFactory.java

@@ -18,6 +18,7 @@ import lol.pyr.znpcsplus.config.ConfigManager;
 import lol.pyr.znpcsplus.entity.EntityPropertyImpl;
 import lol.pyr.znpcsplus.entity.EntityPropertyRegistryImpl;
 import lol.pyr.znpcsplus.entity.PacketEntity;
+import lol.pyr.znpcsplus.entity.properties.attributes.AttributeProperty;
 import lol.pyr.znpcsplus.scheduling.TaskScheduler;
 import lol.pyr.znpcsplus.skin.BaseSkinDescriptor;
 import lol.pyr.znpcsplus.util.NamedColor;
@@ -55,6 +56,7 @@ public class V1_8PacketFactory implements PacketFactory {
                     entity.getUuid(), npcLocationToVector(location), location.getYaw(), location.getPitch(), Collections.emptyList()));
             sendPacket(player, new WrapperPlayServerEntityHeadLook(entity.getEntityId(), location.getYaw()));
             sendAllMetadata(player, entity, properties);
+            sendAllAttributes(player, entity, properties);
             scheduler.runLaterAsync(() -> removeTabPlayer(player, entity), configManager.getConfig().tabHideDelay());
         });
     }
@@ -70,6 +72,7 @@ public class V1_8PacketFactory implements PacketFactory {
                 new WrapperPlayServerSpawnEntity(entity.getEntityId(), Optional.of(entity.getUuid()), entity.getType(), npcLocationToVector(location),
                         location.getPitch(), location.getYaw(), location.getYaw(), 0, Optional.empty()));
         sendAllMetadata(player, entity, properties);
+        if (EntityTypes.isTypeInstanceOf(type, EntityTypes.LIVINGENTITY)) sendAllAttributes(player, entity, properties);
         createTeam(player, entity, properties.getProperty(propertyRegistry.getByName("glow", NamedColor.class)));
     }
 
@@ -187,4 +190,19 @@ public class V1_8PacketFactory implements PacketFactory {
                 WrapperPlayServerEntityAnimation.EntityAnimationType.SWING_OFF_HAND :
                 WrapperPlayServerEntityAnimation.EntityAnimationType.SWING_MAIN_ARM));
     }
+
+    @Override
+    public void sendAllAttributes(Player player, PacketEntity entity, PropertyHolder properties) {
+        List<WrapperPlayServerUpdateAttributes.Property> attributesList = new ArrayList<>();
+        properties.getAppliedProperties()
+                .stream()
+                .filter(property -> property instanceof AttributeProperty)
+                .forEach(property -> ((AttributeProperty) property).apply(player, entity, false, attributesList));
+        sendPacket(player, new WrapperPlayServerUpdateAttributes(entity.getEntityId(), attributesList));
+    }
+
+    @Override
+    public void sendAttribute(Player player, PacketEntity entity, WrapperPlayServerUpdateAttributes.Property property) {
+        sendPacket(player, new WrapperPlayServerUpdateAttributes(entity.getEntityId(), Collections.singletonList(property)));
+    }
 }