Handle mob summon and limbo state

src/main/java/emu/grasscutter/data/binout/AbilityModifier.java

@@ -42,6 +42,7 @@ public class AbilityModifier implements Serializable {
     public String stacking;
 
     public AbilityMixinData[] modifierMixins;
+    public AbilityModifierProperty properties;
 
     public ElementType elementType;
     public DynamicFloat elementDurability = DynamicFloat.ZERO;
@@ -328,6 +329,9 @@ public enum Type {
 
         public int skillID;
         public int resistanceListID;
+        public int monsterID;
+        public int summonTag;
+
 
         public AbilityModifierAction[] actions;
         public AbilityModifierAction[] successActions;
@@ -370,6 +374,11 @@ public enum DropType {
         }
     }
 
+    public static class AbilityModifierProperty implements Serializable {
+        public float Actor_HpThresholdRatio;
+        // Add more properties here when GC needs them.
+    }
+
     public enum State {
         LockHP,
         Invincible,

src/main/java/emu/grasscutter/data/binout/config/fields/ConfigCombat.java

@@ -8,4 +8,5 @@
 public class ConfigCombat {
     // There are more values that can be added that might be useful in the json
     ConfigCombatProperty property;
+    ConfigCombatSummon summon;
 }

src/main/java/emu/grasscutter/data/binout/config/fields/ConfigCombatSummon.java

@@ -0,0 +1,15 @@
+package emu.grasscutter.data.binout.config.fields;
+
+import lombok.*;
+import lombok.experimental.FieldDefaults;
+import java.util.List;
+
+@Data
+public class ConfigCombatSummon {
+    List<SummonTag> summonTags;
+
+    @Getter
+    public final class SummonTag {
+        int summonTag;
+    }
+}

src/main/java/emu/grasscutter/game/ability/Ability.java

@@ -71,6 +71,24 @@ public Ability(AbilityData data, GameEntity owner, Player playerOwner) {
                         .filter(action -> action.type == AbilityModifierAction.Type.AvatarSkillStart)
                         .map(action -> action.skillID)
                         .toList());
+
+        if (data.onAdded != null) {
+            processOnAddedAbilityModifiers();
+        }
+    }
+
+    public void processOnAddedAbilityModifiers() {
+        for (AbilityModifierAction modifierAction : data.onAdded) {
+            if (modifierAction.type == null) continue;
+
+            if (modifierAction.type == AbilityModifierAction.Type.ApplyModifier) {
+                if (modifierAction.modifierName == null) continue;
+                else if (!data.modifiers.containsKey(modifierAction.modifierName)) continue;
+
+                var modifierData = data.modifiers.get(modifierAction.modifierName);
+                owner.onAddAbilityModifier(modifierData);
+            }
+        }
     }
 
     public static String getAbilityName(AbilityString abString) {

src/main/java/emu/grasscutter/game/ability/actions/ActionSummon.java

@@ -0,0 +1,62 @@
+package emu.grasscutter.game.ability.actions;
+
+import com.google.protobuf.ByteString;
+import com.google.protobuf.InvalidProtocolBufferException;
+import emu.grasscutter.Grasscutter;
+import emu.grasscutter.data.GameData;
+import emu.grasscutter.data.binout.AbilityModifier.AbilityModifierAction;
+import emu.grasscutter.game.ability.Ability;
+import emu.grasscutter.game.entity.*;
+import emu.grasscutter.game.world.*;
+import emu.grasscutter.server.packet.send.PacketMonsterSummonTagNotify;
+import emu.grasscutter.net.proto.EPKDEHOJFLIOuterClass.EPKDEHOJFLI;
+import emu.grasscutter.utils.*;
+
+@AbilityAction(AbilityModifierAction.Type.Summon)
+public class ActionSummon extends AbilityActionHandler {
+    @Override
+    public synchronized boolean execute(
+            Ability ability, AbilityModifierAction action, ByteString abilityData, GameEntity target) {
+        EPKDEHOJFLI summonPosRot = null;
+        try {
+            // In game version 4.0, summoned entity's
+            // position and rotation are packed in EPKDEHOJFLI.
+            // This is packet AbilityActionSummon and has two fields:
+            //  4: Vector pos
+            //  13: Vector rot
+            summonPosRot = EPKDEHOJFLI.parseFrom(abilityData);
+        } catch (InvalidProtocolBufferException e) {
+            Grasscutter.getLogger().error("Failed to parse abilityData: {}", Utils.bytesToHex(abilityData.toByteArray()));
+            return false;
+        }
+
+        var pos = new Position(summonPosRot.getPos());
+        var rot = new Position(summonPosRot.getRot());
+        var monsterId = action.monsterID;
+
+        var scene = target.getScene();
+
+        var monsterData = GameData.getMonsterDataMap().get(monsterId);
+        if (monsterData == null) {
+            Grasscutter.getLogger().error("Failed to find monster by ID {}", monsterId);
+            return false;
+        }
+
+        if (target instanceof EntityMonster ownerEntity) {
+            var level = scene.getLevelForMonster(0, ownerEntity.getLevel());
+            var entity = new EntityMonster(scene, monsterData, pos, rot, level);
+            ownerEntity.getSummonTagMap().put(action.summonTag, entity);
+            entity.setSummonedTag(action.summonTag);
+            entity.setOwnerEntityId(target.getId());
+            scene.addEntity(entity);
+            scene.getPlayers().get(0).sendPacket(new PacketMonsterSummonTagNotify(ownerEntity));
+
+            Grasscutter.getLogger().trace("Spawned entityId {} monsterId {} pos {} rot {}, target { {} }, action { {} }",
+                    entity.getId(), monsterId, pos, rot, target, action);
+
+            return true;
+        } else {
+            return false;
+        }
+    }
+}

src/main/java/emu/grasscutter/game/entity/EntityMonster.java

@@ -25,6 +25,7 @@
 import emu.grasscutter.net.proto.SceneEntityInfoOuterClass.SceneEntityInfo;
 import emu.grasscutter.net.proto.SceneMonsterInfoOuterClass.SceneMonsterInfo;
 import emu.grasscutter.net.proto.SceneWeaponInfoOuterClass.SceneWeaponInfo;
+import emu.grasscutter.net.proto.ServantInfoOuterClass.ServantInfo;
 import emu.grasscutter.scripts.constants.EventType;
 import emu.grasscutter.scripts.data.*;
 import emu.grasscutter.server.event.entity.EntityDamageEvent;
@@ -49,6 +50,9 @@ public class EntityMonster extends GameEntity {
     @Getter private final Position bornPos;
     @Getter private final int level;
     @Getter private EntityWeapon weaponEntity;
+    @Getter private Map<Integer, EntityMonster> summonTagMap;
+    @Getter @Setter private int summonedTag;
+    @Getter @Setter private int ownerEntityId;
     @Getter @Setter private int poseId;
     @Getter @Setter private int aiId = -1;
 
@@ -67,6 +71,9 @@ public EntityMonster(
         this.bornPos = this.getPosition().clone();
         this.level = level;
         this.playerOnBattle = new ArrayList<>();
+        this.summonTagMap = new HashMap<>();
+        this.summonedTag = 0;
+        this.ownerEntityId = 0;
 
         if (GameData.getMonsterMappingMap().containsKey(this.getMonsterId())) {
             this.configEntityMonster =
@@ -76,6 +83,14 @@ public EntityMonster(
             this.configEntityMonster = null;
         }
 
+        if (this.configEntityMonster != null &&
+                    this.configEntityMonster.getCombat() != null &&
+                    this.configEntityMonster.getCombat().getSummon() != null &&
+                    this.configEntityMonster.getCombat().getSummon().getSummonTags() != null) {
+            this.configEntityMonster.getCombat().getSummon().getSummonTags().forEach(
+                    t -> this.summonTagMap.put(t.getSummonTag(), null));
+        }
+
         // Monster weapon
         if (getMonsterWeaponId() > 0) {
             this.weaponEntity = new EntityWeapon(scene, getMonsterWeaponId());
@@ -316,6 +331,11 @@ public void onDeath(int killerId) {
                 this.getMonsterData().getType().getValue());
         scene.triggerDungeonEvent(
                 DungeonPassConditionType.DUNGEON_COND_KILL_MONSTER, this.getMonsterId());
+
+        // If this entity spawned servants, kill those too.
+        summonTagMap.values().stream()
+                .filter(Objects::nonNull)
+                .forEach(entity -> scene.killEntity(entity, killerId));
     }
 
     public void recalcStats() {
@@ -387,14 +407,21 @@ public void recalcStats() {
     public SceneEntityInfo toProto() {
         var data = this.getMonsterData();
 
+        var aiInfo =
+                SceneEntityAiInfo.newBuilder()
+                        .setIsAiOpen(true)
+                        .setBornPos(this.getBornPos().toProto());
+        if (ownerEntityId != 0) {
+            aiInfo.setServantInfo(
+                    ServantInfo.newBuilder()
+                            .setMasterEntityId(ownerEntityId));
+        }
+
         var authority =
                 EntityAuthorityInfo.newBuilder()
                         .setAbilityInfo(AbilitySyncStateInfo.newBuilder())
                         .setRendererChangedInfo(EntityRendererChangedInfo.newBuilder())
-                        .setAiInfo(
-                                SceneEntityAiInfo.newBuilder()
-                                        .setIsAiOpen(true)
-                                        .setBornPos(this.getBornPos().toProto()))
+                        .setAiInfo(aiInfo)
                         .setBornPos(this.getBornPos().toProto())
                         .build();
 
@@ -425,7 +452,10 @@ public SceneEntityInfo toProto() {
                         .setAuthorityPeerId(this.getWorld().getHostPeerId())
                         .setPoseId(this.getPoseId())
                         .setBlockId(this.getScene().getId())
+                        .setSummonedTag(this.summonedTag)
+                        .setOwnerEntityId(this.ownerEntityId)
                         .setBornType(MonsterBornType.MONSTER_BORN_TYPE_DEFAULT);
+        summonTagMap.forEach((k, v) -> monsterInfo.putSummonTagMap(k, v == null ? 0 : 1));
 
         if (this.metaMonster != null) {
             if (this.metaMonster.special_name_id != 0) {

src/main/java/emu/grasscutter/game/entity/GameEntity.java

@@ -1,6 +1,8 @@
 package emu.grasscutter.game.entity;
 
+import emu.grasscutter.Grasscutter;
 import emu.grasscutter.data.GameData;
+import emu.grasscutter.data.binout.*;
 import emu.grasscutter.game.ability.*;
 import emu.grasscutter.game.player.Player;
 import emu.grasscutter.game.props.*;
@@ -32,6 +34,8 @@ public abstract class GameEntity {
     @Getter @Setter private int lastMoveReliableSeq;
 
     @Getter @Setter private boolean lockHP;
+    private boolean limbo;
+    private float limboHpThreshold;
 
     @Setter(AccessLevel.PROTECTED)
     @Getter
@@ -110,6 +114,20 @@ public void addAllFightPropsToEntityInfo(SceneEntityInfo.Builder entityInfo) {
                         });
     }
 
+    protected void setLimbo(float hpThreshold) {
+        limbo = true;
+        limboHpThreshold = hpThreshold;
+    }
+
+    public void onAddAbilityModifier(AbilityModifier data) {
+        // Set limbo state (invulnerability at a certain HP threshold)
+        // if ability modifier calls for it
+        if (data.state == AbilityModifier.State.Limbo &&
+                    data.properties != null && data.properties.Actor_HpThresholdRatio > .0f) {
+            this.setLimbo(data.properties.Actor_HpThresholdRatio);
+        }
+    }
+
     protected MotionInfo getMotionInfo() {
         return MotionInfo.newBuilder()
                 .setPos(this.getPosition().toProto())
@@ -167,11 +185,26 @@ public void damage(float amount, int killerId, ElementType attackType) {
             return; // If the event is canceled, do not damage the entity.
         }
 
+        float effectiveDamage = 0;
         float curHp = getFightProperty(FightProperty.FIGHT_PROP_CUR_HP);
-        if (curHp != Float.POSITIVE_INFINITY && !lockHP || lockHP && curHp <= event.getDamage()) {
-            // Add negative HP to the current HP property.
-            this.addFightProperty(FightProperty.FIGHT_PROP_CUR_HP, -(event.getDamage()));
+        if (limbo) {
+            float maxHp = getFightProperty(FightProperty.FIGHT_PROP_MAX_HP);
+            float curRatio = curHp / maxHp;
+            if (curRatio > limboHpThreshold) {
+                // OK if this hit takes HP below threshold.
+                effectiveDamage = event.getDamage();
+            }
+            if (effectiveDamage >= curHp && limboHpThreshold > .0f) {
+                // Don't let entity die while in limbo.
+                effectiveDamage = curHp - 1;
+            }
         }
+        else if (curHp != Float.POSITIVE_INFINITY && !lockHP || lockHP && curHp <= event.getDamage()) {
+            effectiveDamage = event.getDamage();
+        }
+
+        // Add negative HP to the current HP property.
+        this.addFightProperty(FightProperty.FIGHT_PROP_CUR_HP, -effectiveDamage);
 
         this.lastAttackType = attackType;
         this.checkIfDead();

src/main/java/emu/grasscutter/game/world/World.java

@@ -167,7 +167,7 @@ public int getPlayerCount() {
      * @param idType The entity type.
      * @return The next entity ID.
      */
-    public int getNextEntityId(EntityIdType idType) {
+    public synchronized int getNextEntityId(EntityIdType idType) {
         return (idType.getId() << 24) + ++this.nextEntityId;
     }
 

src/main/java/emu/grasscutter/server/packet/send/PacketMonsterSummonTagNotify.java

@@ -0,0 +1,23 @@
+package emu.grasscutter.server.packet.send;
+
+import emu.grasscutter.game.entity.EntityMonster;
+import emu.grasscutter.game.player.Player;
+import emu.grasscutter.game.world.Scene;
+import emu.grasscutter.net.packet.*;
+import emu.grasscutter.net.proto.MonsterSummonTagNotifyOuterClass.MonsterSummonTagNotify;
+import java.util.*;
+import static java.util.Map.entry;
+
+public class PacketMonsterSummonTagNotify extends BasePacket {
+
+    public PacketMonsterSummonTagNotify(EntityMonster monsterEntity) {
+        super(PacketOpcodes.MonsterSummonTagNotify);
+
+        var proto =
+                MonsterSummonTagNotify.newBuilder()
+                        .setMonsterEntityId(monsterEntity.getId());
+        monsterEntity.getSummonTagMap().forEach((k, v) -> proto.putSummonTagMap(k, v == null ? 0 : 1));
+
+        this.setData(proto.build());
+    }
+}