Merge pull request #56 from gnembon/tracing_functions

Tracing functions

src/main/java/carpet/CarpetServer.java

@@ -11,6 +11,7 @@ import carpet.commands.DistanceCommand;
 import carpet.commands.DrawCommand;
 import carpet.commands.InfoCommand;
 import carpet.commands.LogCommand;
+import carpet.commands.MobAICommand;
 import carpet.commands.PerimeterInfoCommand;
 import carpet.commands.PlayerCommand;
 import carpet.commands.ScriptCommand;
@@ -22,6 +23,7 @@ import carpet.script.CarpetScriptServer;
 import carpet.settings.CarpetSettings;
 import carpet.settings.SettingsManager;
 import carpet.utils.HUDController;
+import carpet.utils.MobAI;
 import com.mojang.brigadier.CommandDispatcher;
 import net.minecraft.server.command.ServerCommandSource;
 import net.minecraft.server.MinecraftServer;
@@ -59,6 +61,7 @@ public class CarpetServer // static for now - easier to handle all around the co
             e.onServerLoaded(server);
         });
         scriptServer = new CarpetScriptServer();
+        MobAI.resetTrackers();
     }
 
     public static void tick(MinecraftServer server)
@@ -88,6 +91,7 @@ public class CarpetServer // static for now - easier to handle all around the co
         PerimeterInfoCommand.register(dispatcher);
         DrawCommand.register(dispatcher);
         ScriptCommand.register(dispatcher);
+        MobAICommand.register(dispatcher);
         extensions.forEach(e -> e.registerCommands(dispatcher));
         //TestCommand.register(dispatcher);
     }

src/main/java/carpet/commands/MobAICommand.java

@@ -0,0 +1,42 @@
+package carpet.commands;
+
+import carpet.settings.CarpetSettings;
+import carpet.utils.MobAI;
+import com.mojang.brigadier.CommandDispatcher;
+import com.mojang.brigadier.arguments.StringArgumentType;
+import com.mojang.brigadier.builder.LiteralArgumentBuilder;
+import net.minecraft.command.arguments.EntitySummonArgumentType;
+import net.minecraft.server.command.ServerCommandSource;
+import net.minecraft.util.registry.Registry;
+
+import static net.minecraft.server.command.CommandManager.argument;
+import static net.minecraft.server.command.CommandManager.literal;
+import static net.minecraft.server.command.CommandSource.suggestMatching;
+
+public class MobAICommand
+{
+    public static void register(CommandDispatcher<ServerCommandSource> dispatcher)
+    {
+        LiteralArgumentBuilder<ServerCommandSource> command = literal("track").
+                requires((player) -> CarpetSettings.commandTrackAI).
+                then(argument("entity type", EntitySummonArgumentType.entitySummon()).
+
+                        suggests( (c, b) -> suggestMatching(MobAI.availbleTypes(), b)).
+                        then(literal("clear").executes( (c) ->
+                                {
+                                    MobAI.clearTracking(Registry.ENTITY_TYPE.get(EntitySummonArgumentType.getEntitySummon(c, "entity type")));
+                                    return 1;
+                                }
+                        )).
+                        then(argument("aspect", StringArgumentType.word()).
+                                suggests( (c, b) -> suggestMatching(MobAI.availableFor(Registry.ENTITY_TYPE.get(EntitySummonArgumentType.getEntitySummon(c, "entity type"))),b)).
+                                executes( (c) -> {
+                                    MobAI.startTracking(
+                                            Registry.ENTITY_TYPE.get(EntitySummonArgumentType.getEntitySummon(c, "entity type")),
+                                            MobAI.TrackingType.byName(StringArgumentType.getString(c, "aspect"))
+                                    );
+                                    return 1;
+                                })));
+        dispatcher.register(command);
+    }
+}

src/main/java/carpet/commands/ScriptCommand.java

@@ -14,6 +14,7 @@ import com.mojang.brigadier.CommandDispatcher;
 import com.mojang.brigadier.arguments.StringArgumentType;
 import com.mojang.brigadier.builder.LiteralArgumentBuilder;
 import com.mojang.brigadier.context.CommandContext;
+import com.mojang.brigadier.exceptions.CommandSyntaxException;
 import com.mojang.brigadier.suggestion.Suggestions;
 import com.mojang.brigadier.suggestion.SuggestionsBuilder;
 import net.minecraft.block.Block;
@@ -24,6 +25,7 @@ import net.minecraft.command.arguments.BlockStateArgument;
 import net.minecraft.command.arguments.BlockStateArgumentType;
 import net.minecraft.server.command.ServerCommandSource;
 import net.minecraft.block.entity.BlockEntity;
+import net.minecraft.server.network.ServerPlayerEntity;
 import net.minecraft.util.Clearable;
 import net.minecraft.util.math.BlockPos;
 import net.minecraft.server.world.ServerWorld;
@@ -204,11 +206,19 @@ public class ScriptCommand
         LiteralArgumentBuilder<ServerCommandSource> a = literal("load").requires( (player) -> player.hasPermissionLevel(2) ).
                 then(argument("package", StringArgumentType.word()).
                         suggests( (cc, bb) -> suggestMatching(CarpetServer.scriptServer.listAvailableModules(),bb)).
+                        executes((cc) ->
+                        {
+                            boolean success = CarpetServer.scriptServer.addScriptHost(cc.getSource(), StringArgumentType.getString(cc, "package"), true);
+                            return success?1:0;
+                        }).
+                        then(literal("shared").
                                 executes((cc) ->
                                 {
                                     boolean success = CarpetServer.scriptServer.addScriptHost(cc.getSource(), StringArgumentType.getString(cc, "package"), false);
                                     return success?1:0;
-                        })
+                                }
+                                )
+                        )
                 );
         LiteralArgumentBuilder<ServerCommandSource> f = literal("unload").requires( (player) -> player.hasPermissionLevel(2) ).
                 then(argument("package", StringArgumentType.word()).
@@ -267,8 +277,8 @@ public class ScriptCommand
         try
         {
             String name = StringArgumentType.getString(context, "package").toLowerCase(Locale.ROOT);
-            return CarpetServer.scriptServer.modules.getOrDefault(name, CarpetServer.scriptServer.globalHost);
+            ScriptHost parentHost = CarpetServer.scriptServer.modules.getOrDefault(name, CarpetServer.scriptServer.globalHost);
-
+            return parentHost.retrieveForExecution(context.getSource());
         }
         catch (IllegalArgumentException ignored)
         {
@@ -277,7 +287,6 @@ public class ScriptCommand
     }
     private static Collection<String> suggestFunctionCalls(CommandContext<ServerCommandSource> c)
     {
-        ServerCommandSource s = c.getSource();
         ScriptHost host = getHost(c);
         return host.getPublicFunctions();
     }

src/main/java/carpet/mixins/VillagerEntity_aiMixin.java

@@ -0,0 +1,80 @@
+package carpet.mixins;
+
+import carpet.utils.Messenger;
+import carpet.utils.MobAI;
+import net.minecraft.entity.EntityType;
+import net.minecraft.entity.ai.brain.Activity;
+import net.minecraft.entity.ai.brain.MemoryModuleType;
+import net.minecraft.entity.passive.AbstractTraderEntity;
+import net.minecraft.entity.passive.VillagerEntity;
+import net.minecraft.particle.ParticleTypes;
+import net.minecraft.server.world.ServerWorld;
+import net.minecraft.util.Timestamp;
+import net.minecraft.world.World;
+import org.spongepowered.asm.mixin.Mixin;
+import org.spongepowered.asm.mixin.Shadow;
+import org.spongepowered.asm.mixin.injection.At;
+import org.spongepowered.asm.mixin.injection.Inject;
+import org.spongepowered.asm.mixin.injection.callback.CallbackInfo;
+
+import java.util.Optional;
+
+@Mixin(VillagerEntity.class)
+public abstract class VillagerEntity_aiMixin extends AbstractTraderEntity
+{
+    @Shadow protected abstract boolean hasSeenGolemRecently(long long_1);
+
+    @Inject(method = "tick", at = @At("HEAD"))
+    private void ontick(CallbackInfo ci)
+    {
+        if (MobAI.isTracking(this, MobAI.TrackingType.IRON_GOLEM_SPAWNING) && !getEntityWorld().isClient())
+        {
+            long time;
+            Optional<Long> optional_1 = this.brain.getOptionalMemory(MemoryModuleType.GOLEM_LAST_SEEN_TIME);
+            if (!optional_1.isPresent()) {
+                time = 0;
+            } else {
+                Long long_2 = optional_1.get();
+                time = long_2+600 - getEntityWorld().getTime();
+            }
+            boolean recentlySeen = hasSeenGolemRecently(getEntityWorld().getTime());
+            Optional<Timestamp> optional_11 = this.brain.getOptionalMemory(MemoryModuleType.LAST_SLEPT);
+            Optional<Timestamp> optional_22 = this.brain.getOptionalMemory(MemoryModuleType.LAST_WORKED_AT_POI);
+            boolean work = false;
+            boolean sleep = false;
+            boolean panic = this.brain.hasActivity(Activity.PANIC);
+            long currentTime = this.world.getTime();
+            if (optional_11.isPresent()) {
+                sleep = (currentTime - optional_11.get().getTime()) < 24000L;
+            }
+            if (optional_22.isPresent()) {
+                work = (currentTime - optional_22.get().getTime()) < 36000L;
+            }
+
+            this.setCustomName(Messenger.c(
+                    (sleep?"eb ":"fb ")+"\u263d ",
+                    (work?"eb ":"fb ")+"\u2692 ",//"\u26CF ",
+                    (panic?"lb ":"fb ")+"\u2623 ",//"\u2622 \u2620 \u26A1 ",
+                    (recentlySeen?"rb ":"lb ")+time ));
+            this.setCustomNameVisible(true);
+        }
+    }
+
+    @Inject(method = "summonGolem", at = @At(
+            value = "INVOKE",
+            target = "Lnet/minecraft/util/math/Box;expand(DDD)Lnet/minecraft/util/math/Box;",
+            shift = At.Shift.AFTER
+    ))
+    private void particleIt(long long_1, int int_1, CallbackInfo ci)
+    {
+        if (MobAI.isTracking(this, MobAI.TrackingType.IRON_GOLEM_SPAWNING) && !getEntityWorld().isClient())
+        {
+            ((ServerWorld) getEntityWorld()).spawnParticles(ParticleTypes.BARRIER, x, y+3, z, 1, 0.1, 0.1, 0.1, 0.0);
+        }
+    }
+
+    public VillagerEntity_aiMixin(EntityType<? extends AbstractTraderEntity> entityType_1, World world_1)
+    {
+        super(entityType_1, world_1);
+    }
+}

src/main/java/carpet/script/CarpetEventServer.java

@@ -122,6 +122,11 @@ public class CarpetEventServer
         {
             callList.removeIf((c)->  c.udf.equalsIgnoreCase(callName) && ( hostName == null || c.host.equalsIgnoreCase(hostName) ) );
         }
+
+        public void removeAllCalls(String hostName)
+        {
+            callList.removeIf((c)-> c.host.equals(hostName));
+        }
     }
 
     public Map<String, CallbackList> eventHandlers = new HashMap<>();
@@ -194,6 +199,11 @@ public class CarpetEventServer
         return true;
     }
 
+    public void removeAllHostEvents(String hostName)
+    {
+        eventHandlers.forEach((e, a) -> a.removeAllCalls(hostName));
+    }
+
     private Callback decodeCallback(String funName)
     {
         Pattern find = Pattern.compile("(\\w+)\\(from (\\w+)\\)");

src/main/java/carpet/script/CarpetExpression.java

@@ -35,13 +35,17 @@ import net.minecraft.entity.Entity;
 import net.minecraft.entity.EntityType;
 import net.minecraft.entity.EquipmentSlot;
 import net.minecraft.entity.ItemEntity;
+import net.minecraft.entity.LightningEntity;
 import net.minecraft.entity.LivingEntity;
+import net.minecraft.entity.SpawnType;
 import net.minecraft.entity.decoration.ArmorStandEntity;
+import net.minecraft.entity.mob.MobEntity;
 import net.minecraft.entity.player.PlayerEntity;
 import net.minecraft.item.BlockItem;
 import net.minecraft.item.ItemStack;
 import net.minecraft.item.Items;
 import net.minecraft.nbt.CompoundTag;
+import net.minecraft.nbt.Tag;
 import net.minecraft.particle.ParticleEffect;
 import net.minecraft.predicate.entity.EntityPredicates;
 import net.minecraft.server.MinecraftServer;
@@ -53,6 +57,8 @@ import net.minecraft.sound.SoundCategory;
 import net.minecraft.state.StateFactory;
 import net.minecraft.state.property.Property;
 import net.minecraft.text.LiteralText;
+import net.minecraft.text.TranslatableText;
+import net.minecraft.util.Clearable;
 import net.minecraft.util.Identifier;
 import net.minecraft.util.hit.BlockHitResult;
 import net.minecraft.util.hit.EntityHitResult;
@@ -73,6 +79,7 @@ import org.apache.commons.lang3.tuple.Pair;
 
 import java.util.ArrayList;
 import java.util.Arrays;
+import java.util.Collection;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Locale;
@@ -599,7 +606,7 @@ public class CarpetExpression
                 throw new InternalExpressionException("Block requires at least one parameter");
             }
             CompoundTag tag = BlockValue.fromParams(cc, lv, 0, true).block.getData();
-            if (tag.isEmpty())
+            if (tag == null)
                 return (c_, t_) -> Value.NULL;
             Value retval = new NBTSerializableValue(tag);
             return (c_, t_) -> retval;
@@ -672,7 +679,6 @@ public class CarpetExpression
         this.expr.addLazyFunction("blast_resistance", -1, (c, t, lv) ->
                 genericStateTest(c, "blast_resistance", lv, (s, p, w) -> new NumericValue(s.getBlock().getBlastResistance())));
 
-        // Deprecated
         this.expr.addLazyFunction("top", -1, (c, t, lv) ->
         {
             String type = lv.get(0).evalValue(c).getString().toLowerCase(Locale.ROOT);
@@ -686,20 +692,10 @@ public class CarpetExpression
                 case "surface": htype = Heightmap.Type.WORLD_SURFACE; break;
                 default: throw new InternalExpressionException("Unknown heightmap type: "+type);
             }
-            int x;
+            BlockValue.LocatorResult locator = BlockValue.fromParams((CarpetContext)c, lv, 1);
-            int z;
+            BlockPos pos = locator.block.getPos();
-            Value v1 = lv.get(1).evalValue(c);
+            int x = pos.getX();
-            if (v1 instanceof BlockValue)
+            int z = pos.getZ();
-            {
-                BlockPos inpos = ((BlockValue)v1).getPos();
-                x = inpos.getX();
-                z = inpos.getZ();
-            }
-            else
-            {
-                x = (int) NumericValue.asNumber(lv.get(1).evalValue(c)).getLong();
-                z = (int) NumericValue.asNumber(lv.get(2).evalValue(c)).getLong();
-            }
             Value retval = new NumericValue(((CarpetContext)c).s.getWorld().getChunk(x >> 4, z >> 4).sampleHeightmap(htype, x & 15, z & 15) + 1);
             return (c_, t_) -> retval;
             //BlockPos pos = new BlockPos(x,y,z);
@@ -783,7 +779,8 @@ public class CarpetExpression
                 return (c_, t_) -> Value.FALSE;
             CarpetSettings.impendingFillSkipUpdates = !CarpetSettings.fillUpdates;
             BlockPos targetPos = targetLocator.block.getPos();
-            cc.s.getWorld().setBlockState(targetPos, sourceBlockState, 2);
+            Clearable.clear(world.getBlockEntity(targetPos));
+            world.setBlockState(targetPos, sourceBlockState, 2);
 
             if ( data != null)
             {
@@ -935,32 +932,27 @@ public class CarpetExpression
         {
             BlockValue.LocatorResult locator = BlockValue.fromParams((CarpetContext) c, lv, 0);
             BlockState state = locator.block.getBlockState();
+            if (lv.size() <= locator.offset)
+                throw new InternalExpressionException("property requires to specify a property to query");
             String tag = lv.get(locator.offset).evalValue(c).getString();
             StateFactory<Block, BlockState> states = state.getBlock().getStateFactory();
             Property<?> property = states.getProperty(tag);
             if (property == null)
                 return LazyValue.NULL;
-            Value retval = new StringValue(state.get(property).toString());
+            Value retval = new StringValue(state.get(property).toString().toLowerCase(Locale.ROOT));
             return (_c, _t) -> retval;
         });
 
-        /*this.expr.addLazyFunction("trace_block", -1, (c, t, lv) -> {
+        this.expr.addLazyFunction("block_properties", -1, (c, t, lv) ->
-            Value entityValue = lv.get(0).evalValue(c);
-            if (!(entityValue instanceof EntityValue))
-                throw new InternalExpressionException("First argument of trace_block should be an entity");
-            Entity e = ((EntityValue) entityValue).getEntity();
-            HitResult hitres = Tracer.traceEntityLook(e, 20);
-            switch (hitres.getType())
         {
-                case MISS:
+            BlockValue.LocatorResult locator = BlockValue.fromParams((CarpetContext) c, lv, 0);
-                    return (_c, _t) -> Value.NULL;
+            BlockState state = locator.block.getBlockState();
-                case BLOCK:
+            StateFactory<Block, BlockState> states = state.getBlock().getStateFactory();
-                    return (_c, _t) -> new BlockValue(null, e.getEntityWorld(), ((BlockHitResult)hitres).getBlockPos() );
+            Value res = ListValue.wrap(states.getProperties().stream().map(
-                case ENTITY:
+                    p -> new StringValue(p.getName())).collect(Collectors.toList())
-                    return (_c, _t) -> new EntityValue(((EntityHitResult)hitres).getEntity());
+            );
-            }
+            return (_c, _t) -> res;
-            return LazyValue.NULL;
+        });
-        });*/
 
         this.expr.addLazyFunction("set_biome", -1, (c, t, lv) -> {
             CarpetContext cc = (CarpetContext)c;
@@ -1141,9 +1133,9 @@ public class CarpetExpression
             {
                 Value nbtValue = lv.get(inventoryLocator.offset+3).evalValue(c);
                 if (nbtValue instanceof NBTSerializableValue)
-                    nbt = ((NBTSerializableValue)nbtValue).getTag();
+                    nbt = ((NBTSerializableValue)nbtValue).getCompoundTag();
                 else
-                    nbt = new NBTSerializableValue(nbtValue.getString()).getTag();
+                    nbt = new NBTSerializableValue(nbtValue.getString()).getCompoundTag();
             }
             ItemStackArgument newitem = NBTSerializableValue.parseItem(
                     lv.get(inventoryLocator.offset+2).evalValue(c).getString(),
@@ -1597,6 +1589,60 @@ public class CarpetExpression
             return (cc, tt) -> finalVar;
         });
 
+        this.expr.addLazyFunction("spawn", -1, (c, t, lv) -> {
+            CarpetContext cc = (CarpetContext)c;
+            if (lv.size() < 2)
+                throw new InternalExpressionException("spawn function takes mob name, and position to spawn");
+            String entityString = lv.get(0).evalValue(c).getString();
+            Identifier entityId;
+            try
+            {
+                entityId = Identifier.fromCommandInput(new StringReader(entityString));
+                EntityType type = Registry.ENTITY_TYPE.getOrEmpty(entityId).orElse(null);
+                if (type == null || !type.isSummonable())
+                    return LazyValue.NULL;
+            }
+            catch (CommandSyntaxException exception)
+            {
+                 return LazyValue.NULL;
+            }
+
+            BlockValue.VectorLocator position = BlockValue.locateVec(cc, lv, 1);
+            if (position.fromBlock)
+                position.vec = position.vec.subtract(0, 0.5, 0);
+            CompoundTag tag = new CompoundTag();
+            boolean hasTag = false;
+            if (lv.size() > position.offset)
+            {
+                hasTag = true;
+                tag = new NBTSerializableValue(lv.get(position.offset).evalValue(c).getString()).getCompoundTag();
+            }
+            tag.putString("id", entityId.toString());
+            Vec3d vec3d = position.vec;
+
+            if (EntityType.getId(EntityType.LIGHTNING_BOLT).equals(entityId)) {
+                LightningEntity lightningEntity_1 = new LightningEntity(cc.s.getWorld(), vec3d.x, vec3d.y, vec3d.z, false);
+                cc.s.getWorld().addLightning(lightningEntity_1);
+                cc.s.sendFeedback(new TranslatableText("commands.summon.success", lightningEntity_1.getDisplayName()), true);
+                return LazyValue.NULL;
+            } else {
+                ServerWorld serverWorld = cc.s.getWorld();
+                Entity entity_1 = EntityType.loadEntityWithPassengers(tag, serverWorld, (entity_1x) -> {
+                    entity_1x.setPositionAndAngles(vec3d.x, vec3d.y, vec3d.z, entity_1x.yaw, entity_1x.pitch);
+                    return !serverWorld.method_18768(entity_1x) ? null : entity_1x;
+                });
+                if (entity_1 == null) {
+                    return LazyValue.NULL;
+                } else {
+                    if (!hasTag && entity_1 instanceof MobEntity) {
+                        ((MobEntity)entity_1).initialize(serverWorld, serverWorld.getLocalDifficulty(new BlockPos(entity_1)), SpawnType.COMMAND, null, null);
+                    }
+                    Value res = new EntityValue(entity_1);
+                    return (_c, _t) -> res;
+                }
+            }
+        });
+
         this.expr.addLazyFunction("entity_id", 1, (c, t, lv) ->
         {
             Value who = lv.get(0).evalValue(c);
@@ -1661,7 +1707,6 @@ public class CarpetExpression
             return (c_, t_) -> ListValue.wrap(retlist);
         });
 
-
         this.expr.addLazyFunction("query", -1, (c, t, lv) -> {
             if (lv.size()<2)
             {
@@ -2441,15 +2486,16 @@ public class CarpetExpression
         this.expr.addLazyFunction("print", 1, (c, t, lv) ->
         {
             ServerCommandSource s = ((CarpetContext)c).s;
+            Value res = lv.get(0).evalValue(c);
             if (s.getEntity() instanceof  PlayerEntity)
             {
-                Messenger.m((PlayerEntity) s.getEntity(), "w "+ lv.get(0).evalValue(c).getString());
+                Messenger.m((PlayerEntity) s.getEntity(), "w "+ res.getString());
             }
             else
             {
-                Messenger.m(s, "w "+ lv.get(0).evalValue(c).getString());
+                Messenger.m(s, "w "+ res.getString());
             }
-            return lv.get(0); // pass through for variables
+            return (_c, _t) -> res; // pass through for variables
         });
 
 

src/main/java/carpet/script/CarpetScriptServer.java

@@ -44,7 +44,7 @@ public class CarpetScriptServer
 
     public CarpetScriptServer()
     {
-        globalHost = createMinecraftScriptHost(null, null);
+        globalHost = createMinecraftScriptHost(null, null, false, null);
         events = new CarpetEventServer();
         modules = new HashMap<>();
         tickStart = 0L;
@@ -56,19 +56,10 @@ public class CarpetScriptServer
 
     ModuleInterface getModule(String name)
     {
-        for (ModuleInterface moduleData : bundledModuleData)
-        {
-            if (moduleData.getName().equalsIgnoreCase(name))
-            {
-                return moduleData;
-            }
-        }
-
         File folder = CarpetServer.minecraft_server.getLevelStorage().resolveFile(
                 CarpetServer.minecraft_server.getLevelName(), "scripts");
         File[] listOfFiles = folder.listFiles();
-        if (listOfFiles == null)
+        if (listOfFiles != null)
-            return null;
             for (File script : listOfFiles)
             {
                 if (script.getName().equalsIgnoreCase(name+".sc"))
@@ -76,6 +67,13 @@ public class CarpetScriptServer
                     return new FileModule(script);
                 }
             }
+        for (ModuleInterface moduleData : bundledModuleData)
+        {
+            if (moduleData.getName().equalsIgnoreCase(name))
+            {
+                return moduleData;
+            }
+        }
         return null;
     }
 
@@ -84,7 +82,6 @@ public class CarpetScriptServer
         List<String> moduleNames = new ArrayList<>();
         for (ModuleInterface mi: bundledModuleData)
         {
-            if (!modules.containsKey(mi.getName()))
             moduleNames.add(mi.getName());
         }
         File folder = CarpetServer.minecraft_server.getLevelStorage().resolveFile(
@@ -97,7 +94,6 @@ public class CarpetScriptServer
             if (script.getName().endsWith(".sc"))
             {
                 String name = script.getName().replaceFirst("\\.sc","").toLowerCase(Locale.ROOT);
-                if (!modules.containsKey(name))
                 moduleNames.add(name);
             }
         }
@@ -112,12 +108,35 @@ public class CarpetScriptServer
     }
 
 
-    private static ScriptHost createMinecraftScriptHost(String name, ModuleInterface code)
+    private ScriptHost createMinecraftScriptHost(String name, ModuleInterface module, boolean perPlayer, ServerCommandSource source)
     {
-        ScriptHost host = new ScriptHost(name);
+        ScriptHost host = new ScriptHost(name, module, perPlayer );
         host.globalVariables.put("_x", (c, t) -> Value.ZERO);
         host.globalVariables.put("_y", (c, t) -> Value.ZERO);
         host.globalVariables.put("_z", (c, t) -> Value.ZERO);
+        // parse code and convert to expression
+        if (module != null)
+        {
+            try
+            {
+                String code = module.getCode();
+                if (code == null)
+                {
+                    Messenger.m(source, "r Unable to load the package - not found");
+                    return null;
+                }
+                setChatErrorSnooper(source);
+                CarpetExpression ex = new CarpetExpression(code, source, new BlockPos(0, 0, 0));
+                ex.getExpr().asAModule();
+                ex.scriptRunCommand(host, new BlockPos(source.getPosition()));
+            }
+            catch (CarpetExpressionException e)
+            {
+                Messenger.m(source, "r Exception white evaluating expression at " + new BlockPos(source.getPosition()) + ": " + e.getMessage());
+                resetErrorSnooper();
+                return null;
+            }
+        }
         return host;
     }
 
@@ -126,7 +145,12 @@ public class CarpetScriptServer
         //TODO add per player modules to support player actions better on a server
         name = name.toLowerCase(Locale.ROOT);
         ModuleInterface module = getModule(name);
-        ScriptHost newHost = createMinecraftScriptHost(name, module);
+        ScriptHost newHost = createMinecraftScriptHost(name, module, perPlayer, source);
+        if (newHost == null)
+        {
+            Messenger.m(source, "r Failed to add a module");
+            return false;
+        }
         if (module == null)
         {
             Messenger.m(source, "r Unable to locate the package, but created empty host "+name+" instead");
@@ -134,27 +158,12 @@ public class CarpetScriptServer
             return true;
         }
         String code = module.getCode();
-        if (code == null)
+        if (module.getCode() == null)
         {
             Messenger.m(source, "r Unable to load the package - not found");
             return false;
         }
-        // parse code and convert to expression
+
-        // fill functions etc.
-        // possibly add a command
-        try
-        {
-            setChatErrorSnooper(source);
-            CarpetExpression ex = new CarpetExpression(module.getCode(), source, new BlockPos(0, 0, 0));
-            ex.getExpr().asAModule();
-            ex.scriptRunCommand(newHost, new BlockPos(source.getPosition()));
-        }
-        catch (CarpetExpressionException e)
-        {
-            Messenger.m(source, "r Exception white evaluating expression at "+new BlockPos(source.getPosition())+": "+e.getMessage());
-            resetErrorSnooper();
-            return false;
-        }
         modules.put(name, newHost);
 
         addEvents(source, name);
@@ -206,7 +215,7 @@ public class CarpetScriptServer
                 requires((player) -> modules.containsKey(hostName)).
                 executes( (c) ->
                 {
-                    Messenger.m(c.getSource(), "gi "+modules.get(hostName).call(c.getSource(),"__command", null, ""));
+                    Messenger.m(c.getSource(), "gi "+modules.get(hostName).retrieveForExecution(c.getSource()).call(c.getSource(),"__command", null, ""));
                     return 1;
                 });
 
@@ -218,7 +227,7 @@ public class CarpetScriptServer
                             executes( (c) -> {
                                 Messenger.m(
                                         c.getSource(),
-                                        "gi "+modules.get(hostName).call(
+                                        "gi "+modules.get(hostName).retrieveForExecution(c.getSource()).call(
                                                 c.getSource(),
                                                 function,
                                                 null,
@@ -231,7 +240,7 @@ public class CarpetScriptServer
                                     executes( (c) -> {
                                         Messenger.m(
                                                 c.getSource(),
-                                                "gi "+modules.get(hostName).call(
+                                                "gi "+modules.get(hostName).retrieveForExecution(c.getSource()).call(
                                                         c.getSource(),
                                                         function,
                                                         null,
@@ -304,6 +313,7 @@ public class CarpetScriptServer
             return false;
         }
         // stop all events associated with name
+        events.removeAllHostEvents(name);
         modules.remove(name);
         CarpetServer.settingsManager.notifyPlayersCommandsChanged();
         Messenger.m(source, "w Removed host "+name);
@@ -319,7 +329,7 @@ public class CarpetScriptServer
     {
         ScriptHost host = globalHost;
         if (hostname != null)
-            host = modules.get(hostname);
+            host = modules.get(hostname).retrieveForExecution(source);
         try
         {
             host.callUDF(origin, source, host.globalFunctions.get(udf_name), argv);

src/main/java/carpet/script/Expression.java

@@ -498,21 +498,9 @@ public class Expression implements Cloneable
                     Value.assertNotNull(v);
                     return lazyfun.apply(c, t, v);
                 }
-                catch (InternalExpressionException exc)
+                catch (RuntimeException exc)
                 {
-                    throw new ExpressionException(e, token, exc.getMessage());
+                    throw handleCodeException(exc, e, token);
-                }
-                catch (ArithmeticException exc)
-                {
-                    throw new ExpressionException(e, token, "Your math is wrong, "+exc.getMessage());
-                }
-                catch (ExitStatement exit)
-                {
-                    throw exit;
-                }
-                catch (Exception exc)
-                {
-                    throw new ExpressionException(e, token, "Error while evaluating expression: "+exc.getMessage());
                 }
             }
         });
@@ -532,21 +520,9 @@ public class Expression implements Cloneable
                     Value.assertNotNull(v1, v2);
                     return lazyfun.apply(c, type, e, t, v1, v2);
                 }
-                catch (InternalExpressionException exc) // might not actually throw it
+                catch (RuntimeException exc)
                 {
-                    throw new ExpressionException(e, t, exc.getMessage());
+                    throw handleCodeException(exc, e, t);
-                }
-                catch (ArithmeticException exc)
-                {
-                    throw new ExpressionException(e, t, "Your math is wrong, "+exc.getMessage());
-                }
-                catch (ExitStatement exit)
-                {
-                    throw exit;
-                }
-                catch (Exception exc)
-                {
-                    throw new ExpressionException(e, t, "Error while evaluating expression: "+exc.getMessage());
                 }
             }
         });
@@ -565,26 +541,27 @@ public class Expression implements Cloneable
                     Value.assertNotNull(v1, v2);
                     return lazyfun.apply(c, t, v1, v2);
                 }
-                catch (InternalExpressionException exc)
+                catch (RuntimeException exc)
                 {
-                    throw new ExpressionException(e, token, exc.getMessage());
+                    throw handleCodeException(exc, e, token);
-                }
-                catch (ArithmeticException exc)
-                {
-                    throw new ExpressionException(e, token, "Your math is wrong, "+exc.getMessage());
-                }
-                catch (ExitStatement exit)
-                {
-                    throw exit;
-                }
-                catch (Exception exc)
-                {
-                    throw new ExpressionException(e, token, "Error while evaluating expression: "+exc.getMessage());
                 }
             }
         });
     }
 
+    private RuntimeException handleCodeException(RuntimeException exc, Expression e, Tokenizer.Token token)
+    {
+        if (exc instanceof ExitStatement)
+            return exc;
+        if (exc instanceof InternalExpressionException)
+            return new ExpressionException(e, token, exc.getMessage());
+        if (exc instanceof ArithmeticException)
+            return new ExpressionException(e, token, "Your math is wrong, "+exc.getMessage());
+        if (exc instanceof ExpressionException)
+            return exc;
+        return new ExpressionException(e, token, "Error while evaluating expression: "+exc.getMessage());
+    }
+
     private void addUnaryOperator(String surface, boolean leftAssoc, Function<Value, Value> fun)
     {
         operators.put(surface+"u", new AbstractUnaryOperator(precedence.get("unary+-!"), leftAssoc)
@@ -679,21 +656,9 @@ public class Expression implements Cloneable
                 {
                     return fun.apply(c, i, lazyParams);
                 }
-                catch (InternalExpressionException exc)
+                catch (RuntimeException exc)
                 {
-                    throw new ExpressionException(e, t, exc.getMessage());
+                    throw handleCodeException(exc, e, t);
-                }
-                catch (ArithmeticException exc)
-                {
-                    throw new ExpressionException(e, t, "Your math is wrong, "+exc.getMessage());
-                }
-                catch (ExitStatement exit)
-                {
-                    throw exit;
-                }
-                catch (Exception exc)
-                {
-                    throw new ExpressionException(e, t, "Error while evaluating expression: "+exc.getMessage());
                 }
             }
         });
@@ -770,7 +735,7 @@ public class Expression implements Cloneable
                 {
                     throw new ExpressionException(function_context, t, "Your math is wrong, "+exc.getMessage());
                 }
-                catch (ExitStatement exit)
+                catch (ExitStatement | ExpressionException exit)
                 {
                     throw exit;
                 }
@@ -1060,7 +1025,7 @@ public class Expression implements Cloneable
                 Value ret = lv.get(lv.size() - 1).evalValue(c);
                 return (cc, tt) -> ret;
             }
-            return (cc, tt) -> Value.ZERO;
+            return (cc, tt) -> Value.NULL;
         });
     }
 
@@ -1892,18 +1857,7 @@ public class Expression implements Cloneable
             return LazyListValue.range(from, to, step);
         });
 
-        addBinaryFunction("get", (v1, v2) ->
+        addBinaryFunction("get", (v1, v2) -> v1.getElementAt(v2));
-        {
-            if (v1 instanceof LazyListValue || !(v1 instanceof ListValue))
-                throw new InternalExpressionException("First argument of get should be a list");
-            List<Value> items = ((ListValue)v1).getItems();
-            long index = NumericValue.asNumber(v2).getLong();
-            int numitems = items.size();
-            long range = abs(index)/numitems;
-            index += (range+2)*numitems;
-            index = index % numitems;
-            return items.get((int)index);
-        });
 
         //Deprecated, use "get" instead
         addBinaryFunction("element", (v1, v2) ->
@@ -2521,6 +2475,8 @@ public class Expression implements Cloneable
             }
         });
 
+        addUnaryFunction("type", v -> new StringValue(v.getTypeString()));
+
         addUnaryFunction("length", v -> new NumericValue(v.length()));
         addLazyFunction("rand", 1, (c, t, lv) -> {
             Value argument = lv.get(0).evalValue(c);

src/main/java/carpet/script/ScriptHost.java

@@ -8,7 +8,9 @@ import carpet.script.exception.InvalidCallbackException;
 import carpet.script.value.NumericValue;
 import carpet.script.value.StringValue;
 import carpet.script.value.Value;
+import com.mojang.brigadier.exceptions.CommandSyntaxException;
 import net.minecraft.server.command.ServerCommandSource;
+import net.minecraft.server.network.ServerPlayerEntity;
 import net.minecraft.util.math.BlockPos;
 
 import java.math.BigInteger;
@@ -23,22 +25,21 @@ import static java.lang.Math.max;
 
 public class ScriptHost
 {
-
+    public final Map<String, ScriptHost> userHosts = new HashMap<>();
-    public final Map<String, UserDefinedFunction> globalFunctions = new HashMap<>();
+    public Map<String, UserDefinedFunction> globalFunctions = new HashMap<>();
-
+    public Map<String, LazyValue> globalVariables = new HashMap<>();
-    public final Map<String, LazyValue> globalVariables = new HashMap<>();
 
     private String name;
     public String getName() {return name;}
 
-    private ModuleInterface myCode;
+    private final ModuleInterface myCode;
+    public final boolean perUser;
 
-    ScriptHost(String name) { this(name, null);}
+    ScriptHost(String name, ModuleInterface code, boolean perUser)
-
-    ScriptHost(String name, ModuleInterface code)
     {
         this.name = name;
         this.myCode = code;
+        this.perUser = perUser;
         globalVariables.put("euler", (c, t) -> Expression.euler);
         globalVariables.put("pi", (c, t) -> Expression.PI);
         globalVariables.put("null", (c, t) -> Value.NULL);
@@ -51,6 +52,35 @@ public class ScriptHost
         globalVariables.put("_a", (c, t) -> Value.ZERO);
     }
 
+    public ScriptHost retrieveForExecution(String /*Nullable*/ user)
+    {
+        if (!perUser)
+            return this;
+        ScriptHost userHost = userHosts.get(user);
+        if (userHost != null)
+            return userHost;
+        userHost = new ScriptHost(this.name, myCode, false);
+        userHost.globalVariables.putAll(this.globalVariables);
+        userHost.globalFunctions.putAll(this.globalFunctions);
+        userHosts.put(user, userHost);
+        return userHost;
+    }
+
+    public ScriptHost retrieveForExecution(ServerCommandSource source)
+    {
+        if (!perUser)
+            return this;
+        try
+        {
+            ServerPlayerEntity player = source.getPlayer();
+            return retrieveForExecution(player.getName().getString());
+        }
+        catch (CommandSyntaxException e)
+        {
+            return retrieveForExecution((String)null);
+        }
+    }
+
     public Expression getExpressionForFunction(String name)
     {
         return globalFunctions.get(name).getExpression();
@@ -190,4 +220,6 @@ public class ScriptHost
             CarpetSettings.LOG.error("Callback failed: "+e.getMessage());
         }
     }
+
+
 }

src/main/java/carpet/script/value/BlockValue.java

@@ -78,7 +78,7 @@ public class BlockValue extends Value
             Value v1 = params.get(0 + offset).evalValue(c);
             if (v1 instanceof BlockValue)
             {
-                return new VectorLocator(new Vec3d(((BlockValue) v1).getPos()).add(0.5,0.5,0.5), 1+offset);
+                return (new VectorLocator(new Vec3d(((BlockValue) v1).getPos()).add(0.5,0.5,0.5), 1+offset)).fromBlock();
             }
             if (v1 instanceof ListValue)
             {
@@ -241,6 +241,12 @@ public class BlockValue extends Value
         return this != NULL && !getBlockState().isAir();
     }
 
+    @Override
+    public String getTypeString()
+    {
+        return "block";
+    }
+
     @Override
     public Value clone()
     {
@@ -270,6 +276,7 @@ public class BlockValue extends Value
         public int offset;
         public double yaw;
         public double pitch;
+        public boolean fromBlock;
         VectorLocator(Vec3d v, int o)
         {
             vec = v;
@@ -284,6 +291,12 @@ public class BlockValue extends Value
             yaw = y;
             pitch = p;
         }
+
+        public VectorLocator fromBlock()
+        {
+            fromBlock = true;
+            return this;
+        }
     }
 
     public enum SpecificDirection {

src/main/java/carpet/script/value/EntityValue.java

@@ -1,9 +1,11 @@
 package carpet.script.value;
 
 import carpet.fakes.MobEntityInterface;
+import carpet.helpers.Tracer;
 import carpet.script.exception.InternalExpressionException;
 import com.mojang.brigadier.StringReader;
 import com.mojang.brigadier.exceptions.CommandSyntaxException;
+import net.minecraft.client.network.packet.EntityPositionS2CPacket;
 import net.minecraft.client.network.packet.EntityVelocityUpdateS2CPacket;
 import net.minecraft.command.EntitySelector;
 import net.minecraft.command.EntitySelectorReader;
@@ -26,8 +28,12 @@ import net.minecraft.nbt.Tag;
 import net.minecraft.predicate.entity.EntityPredicates;
 import net.minecraft.server.command.ServerCommandSource;
 import net.minecraft.server.network.ServerPlayerEntity;
+import net.minecraft.server.world.ServerWorld;
 import net.minecraft.text.LiteralText;
 import net.minecraft.util.Identifier;
+import net.minecraft.util.hit.BlockHitResult;
+import net.minecraft.util.hit.EntityHitResult;
+import net.minecraft.util.hit.HitResult;
 import net.minecraft.util.math.BlockPos;
 import net.minecraft.util.math.Direction;
 import net.minecraft.util.math.Vec3d;
@@ -122,6 +128,12 @@ public class EntityValue extends Value
         return this.get(what, null);
     }
 
+    @Override
+    public String getTypeString()
+    {
+        return "entity";
+    }
+
     public static Pair<EntityType<?>, Predicate<? super Entity>> getPredicate(String who)
     {
         Pair<EntityType<?>, Predicate<? super Entity>> res = entityPredicates.get(who);
@@ -308,31 +320,76 @@ public class EntityValue extends Value
             return new StringValue(Direction.getEntityFacingOrder(e)[index].asString());
         });
 
+        put("trace", (e, a) ->
+        {
+            float reach = 4.5f;
+            boolean entities = true;
+            boolean liquids = false;
+
+            if (a!=null)
+            {
+                if (!(a instanceof ListValue))
+                {
+                    reach = (float) NumericValue.asNumber(a).getDouble();
+                }
+                else
+                {
+                    List<Value> args = ((ListValue) a).getItems();
+                    if (args.size()==0)
+                        throw new InternalExpressionException("trace needs more arguments");
+                    reach = (float) NumericValue.asNumber(args.get(0)).getDouble();
+                    if (args.size() > 1)
+                    {
+                        entities = false;
+                        for (int i = 1; i < args.size(); i++)
+                        {
+                            String what = args.get(i).getString();
+                            if (what.equalsIgnoreCase("entities"))
+                                entities = true;
+                            else if (what.equalsIgnoreCase("blocks")) {}
+                            else if (what.equalsIgnoreCase("liquids"))
+                                liquids = true;
+                            else throw new InternalExpressionException("Incorrect tracing: "+what);
+                        }
+                    }
+                }
+            }
+            else if (e instanceof ServerPlayerEntity && ((ServerPlayerEntity) e).interactionManager.isCreative())
+            {
+                reach = 5.0f;
+            }
+
+            HitResult hitres;
+            if (entities)
+                hitres = Tracer.rayTrace(e, 1, reach, liquids);
+            else
+                hitres = Tracer.rayTraceBlocks(e, 1, reach, liquids);
+
+            switch (hitres.getType())
+            {
+                case MISS: return Value.NULL;
+                case BLOCK: return new BlockValue(null, e.getEntityWorld(), ((BlockHitResult)hitres).getBlockPos() );
+                case ENTITY: return new EntityValue(((EntityHitResult)hitres).getEntity());
+            }
+            return Value.NULL;
+        });
+
         put("nbt",(e, a) -> {
             CompoundTag nbttagcompound = e.toTag((new CompoundTag()));
             if (a==null)
-                return new StringValue(nbttagcompound.toString());
+                return new NBTSerializableValue(nbttagcompound);//StringValue(nbttagcompound.toString());
-            NbtPathArgumentType.NbtPath path;
+            NbtPathArgumentType.NbtPath path = NBTSerializableValue.cachePath(a.getString());
-            try
-            {
-                path = NbtPathArgumentType.nbtPath().method_9362(new StringReader(a.getString()));
-            }
-            catch (CommandSyntaxException exc)
-            {
-                throw new InternalExpressionException("Incorrect path: "+a.getString());
-            }
-            String res = null;
             try
             {
                 List<Tag> tags = path.get(nbttagcompound);
                 if (tags.size()==0)
                     return Value.NULL;
                 if (tags.size()==1)
-                    return new StringValue(tags.get(0).toText().getString());
+                    return NBTSerializableValue.decodeTag(tags.get(0));
-                return ListValue.wrap(tags.stream().map((t) -> new StringValue(t.toText().getString())).collect(Collectors.toList()));
+                return ListValue.wrap(tags.stream().map(NBTSerializableValue::decodeTag).collect(Collectors.toList()));
             }
             catch (CommandSyntaxException ignored) { }
-            return new StringValue(res);
+            return Value.NULL;
         });
     }};
     private static <Req extends Entity> Req assertEntityArgType(Class<Req> klass, Value arg)
@@ -356,6 +413,21 @@ public class EntityValue extends Value
         featureModifiers.get(what).accept(entity, toWhat);
     }
 
+    private static void updatePosition(Entity e)
+    {
+        if (e instanceof ServerPlayerEntity)
+            ((ServerPlayerEntity)e).networkHandler.requestTeleport(e.x, e.y, e.z, e.yaw, e.pitch);
+        else
+            ((ServerWorld)e.getEntityWorld()).method_14178().sendToNearbyPlayers(e,new EntityPositionS2CPacket(e));
+    }
+
+    private static void updateVelocity(Entity e)
+    {
+        ((ServerWorld)e.getEntityWorld()).method_14178().sendToNearbyPlayers(e, new EntityVelocityUpdateS2CPacket(e));
+    }
+
+
+
     private static Map<String, BiConsumer<Entity, Value>> featureModifiers = new HashMap<String, BiConsumer<Entity, Value>>() {{
         put("remove", (entity, value) -> entity.remove());
         put("health", (e, v) -> { if (e instanceof LivingEntity) ((LivingEntity) e).setHealth((float) NumericValue.asNumber(v).getDouble()); });
@@ -375,8 +447,7 @@ public class EntityValue extends Value
             e.yaw = (float) NumericValue.asNumber(coords.get(3)).getDouble();
             e.prevYaw = e.yaw;
             e.setPosition(e.x, e.y, e.z);
-            if (e instanceof ServerPlayerEntity)
+            updatePosition(e);
-                ((ServerPlayerEntity)e).networkHandler.requestTeleport(e.x, e.y, e.z, e.yaw, e.pitch);
         });
         put("pos", (e, v) ->
         {
@@ -389,43 +460,37 @@ public class EntityValue extends Value
             e.y = NumericValue.asNumber(coords.get(1)).getDouble();
             e.z = NumericValue.asNumber(coords.get(2)).getDouble();
             e.setPosition(e.x, e.y, e.z);
-            if (e instanceof ServerPlayerEntity)
+            updatePosition(e);
-                ((ServerPlayerEntity)e).networkHandler.requestTeleport(e.x, e.y, e.z, e.yaw, e.pitch);
         });
         put("x", (e, v) ->
         {
             e.x = NumericValue.asNumber(v).getDouble();
             e.setPosition(e.x, e.y, e.z);
-            if (e instanceof ServerPlayerEntity)
+            updatePosition(e);
-                ((ServerPlayerEntity)e).networkHandler.requestTeleport(e.x, e.y, e.z, e.yaw, e.pitch);
         });
         put("y", (e, v) ->
         {
             e.y = NumericValue.asNumber(v).getDouble();
             e.setPosition(e.x, e.y, e.z);
-            if (e instanceof ServerPlayerEntity)
+            updatePosition(e);
-                ((ServerPlayerEntity)e).networkHandler.requestTeleport(e.x, e.y, e.z, e.yaw, e.pitch);
         });
         put("z", (e, v) ->
         {
             e.z = NumericValue.asNumber(v).getDouble();
             e.setPosition(e.x, e.y, e.z);
-            if (e instanceof ServerPlayerEntity)
+            updatePosition(e);
-                ((ServerPlayerEntity)e).networkHandler.requestTeleport(e.x, e.y, e.z, e.yaw, e.pitch);
         });
         put("pitch", (e, v) ->
         {
             e.pitch = (float) NumericValue.asNumber(v).getDouble();
             e.prevPitch = e.pitch;
-            if (e instanceof ServerPlayerEntity)
+            updatePosition(e);
-                ((ServerPlayerEntity)e).networkHandler.requestTeleport(e.x, e.y, e.z, e.yaw, e.pitch);
         });
         put("yaw", (e, v) ->
         {
             e.yaw = (float) NumericValue.asNumber(v).getDouble();
             e.prevYaw = e.yaw;
-            if (e instanceof ServerPlayerEntity)
+            updatePosition(e);
-                ((ServerPlayerEntity)e).networkHandler.requestTeleport(e.x, e.y, e.z, e.yaw, e.pitch);
         });
         //"look"
         //"turn"
@@ -442,8 +507,7 @@ public class EntityValue extends Value
             e.y += NumericValue.asNumber(coords.get(1)).getDouble();
             e.z += NumericValue.asNumber(coords.get(2)).getDouble();
             e.setPosition(e.x, e.y, e.z);
-            if (e instanceof ServerPlayerEntity)
+            updatePosition(e);
-                ((ServerPlayerEntity)e).networkHandler.requestTeleport(e.y, e.y, e.z, e.yaw, e.pitch);
         });
 
         put("motion", (e, v) ->
@@ -458,29 +522,25 @@ public class EntityValue extends Value
                     NumericValue.asNumber(coords.get(1)).getDouble(),
                     NumericValue.asNumber(coords.get(2)).getDouble()
             );
-            if (e instanceof ServerPlayerEntity)
+            updateVelocity(e);
-                ((ServerPlayerEntity)e).networkHandler.sendPacket(new EntityVelocityUpdateS2CPacket(e));
         });
         put("motion_x", (e, v) ->
         {
             Vec3d velocity = e.getVelocity();
             e.setVelocity(NumericValue.asNumber(v).getDouble(), velocity.y, velocity.z);
-            if (e instanceof ServerPlayerEntity)
+            updateVelocity(e);
-                ((ServerPlayerEntity)e).networkHandler.sendPacket(new EntityVelocityUpdateS2CPacket(e));
         });
         put("motion_y", (e, v) ->
         {
             Vec3d velocity = e.getVelocity();
             e.setVelocity(velocity.x, NumericValue.asNumber(v).getDouble(), velocity.z);
-            if (e instanceof ServerPlayerEntity)
+            updateVelocity(e);
-                ((ServerPlayerEntity)e).networkHandler.sendPacket(new EntityVelocityUpdateS2CPacket(e));
         });
         put("motion_z", (e, v) ->
         {
             Vec3d velocity = e.getVelocity();
             e.setVelocity(velocity.x, velocity.y, NumericValue.asNumber(v).getDouble());
-            if (e instanceof ServerPlayerEntity)
+            updateVelocity(e);
-                ((ServerPlayerEntity)e).networkHandler.sendPacket(new EntityVelocityUpdateS2CPacket(e));
         });
 
         put("accelerate", (e, v) ->
@@ -495,14 +555,17 @@ public class EntityValue extends Value
                     NumericValue.asNumber(coords.get(1)).getDouble(),
                     NumericValue.asNumber(coords.get(2)).getDouble()
             );
-            if (e instanceof ServerPlayerEntity)
+            updateVelocity(e);
-                ((ServerPlayerEntity)e).networkHandler.sendPacket(new EntityVelocityUpdateS2CPacket(e));
 
         });
         put("custom_name", (e, v) -> {
-            String name = v.getString();
+            if (v instanceof NullValue)
-            if (name.isEmpty())
+            {
+                e.setCustomNameVisible(false);
                 e.setCustomName(null);
+                return;
+            }
+            e.setCustomNameVisible(true);
             e.setCustomName(new LiteralText(v.getString()));
         });
         put("dismount", (e, v) -> e.stopRiding() );

src/main/java/carpet/script/value/FunctionSignatureValue.java

@@ -1,7 +1,7 @@
 package carpet.script.value;
 
 import carpet.script.exception.ExpressionException;
-import carpet.script.value.Value;
+import carpet.script.exception.InternalExpressionException;
 
 import java.util.List;
 
@@ -23,6 +23,12 @@ public class FunctionSignatureValue extends Value
         throw new ExpressionException("Function "+identifier+" is not defined yet");
     }
 
+    @Override
+    public String getTypeString()
+    {
+        throw new InternalExpressionException("How did you get here? Cannot get type of an internal struct.");
+    }
+
     @Override
     public Value clone()
     {

src/main/java/carpet/script/value/GlobalValue.java

@@ -1,6 +1,6 @@
 package carpet.script.value;
 
-import carpet.script.value.Value;
+import carpet.script.exception.InternalExpressionException;
 
 public class GlobalValue extends Value
 {
@@ -21,4 +21,10 @@ public class GlobalValue extends Value
     {
         return false;
     }
+
+    @Override
+    public String getTypeString()
+    {
+        throw new InternalExpressionException("How did you get here? Cannot get type of an internal struct.");
+    }
 }

src/main/java/carpet/script/value/LazyListValue.java

@@ -106,4 +106,15 @@ public abstract class LazyListValue extends ListValue implements Iterator<Value>
         return false;
     }
 
+    @Override
+    public Value getElementAt(Value v2)
+    {
+        throw new InternalExpressionException("get element can only be obtained for regular lists");
+    }
+    @Override
+    public String getTypeString()
+    {
+        return "iterator";
+    }
+
 }

src/main/java/carpet/script/value/ListValue.java

@@ -316,6 +316,22 @@ public class ListValue extends Value
         return (double)items.size();
     }
 
+    @Override
+    public Value getElementAt(Value value)
+    {
+        long index = NumericValue.asNumber(value).getLong();
+        int numitems = items.size();
+        long range = abs(index)/numitems;
+        index += (range+2)*numitems;
+        index = index % numitems;
+        return items.get((int)index);
+    }
+    @Override
+    public String getTypeString()
+    {
+        return "list";
+    }
+
 
 
 }

src/main/java/carpet/script/value/NBTSerializableValue.java

@@ -8,24 +8,28 @@ import com.mojang.brigadier.exceptions.CommandSyntaxException;
 import net.minecraft.block.entity.HopperBlockEntity;
 import net.minecraft.command.arguments.ItemStackArgument;
 import net.minecraft.command.arguments.ItemStringReader;
+import net.minecraft.command.arguments.NbtPathArgumentType;
 import net.minecraft.entity.Entity;
 import net.minecraft.entity.passive.VillagerEntity;
 import net.minecraft.entity.player.PlayerEntity;
 import net.minecraft.inventory.Inventory;
 import net.minecraft.item.ItemStack;
+import net.minecraft.nbt.AbstractNumberTag;
 import net.minecraft.nbt.CompoundTag;
 import net.minecraft.nbt.StringNbtReader;
+import net.minecraft.nbt.Tag;
 import net.minecraft.util.math.BlockPos;
 
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
 import java.util.function.Supplier;
+import java.util.stream.Collectors;
 
 public class NBTSerializableValue extends Value
 {
     private String nbtString = null;
-    private CompoundTag nbtTag = null;
+    private Tag nbtTag = null;
     private Supplier<CompoundTag> nbtSupplier = null;
 
     public NBTSerializableValue(ItemStack stack)
@@ -48,7 +52,7 @@ public class NBTSerializableValue extends Value
         };
     }
 
-    public NBTSerializableValue(CompoundTag tag)
+    public NBTSerializableValue(Tag tag)
     {
         nbtTag = tag;
     }
@@ -152,7 +156,17 @@ public class NBTSerializableValue extends Value
         return slot;
     }
 
-    public CompoundTag getTag()
+    public static Value decodeTag(Tag t)
+    {
+        if (t instanceof CompoundTag)
+            return new NBTSerializableValue(t);
+        if (t instanceof AbstractNumberTag)
+            return new NumericValue(((AbstractNumberTag) t).getDouble());
+        // more can be done here
+        return new StringValue(t.asString());
+    }
+
+    public Tag getTag()
     {
         if (nbtTag == null)
             nbtTag = nbtSupplier.get();
@@ -181,6 +195,18 @@ public class NBTSerializableValue extends Value
         return true;
     }
 
+    public CompoundTag getCompoundTag()
+    {
+        try
+        {
+            return (CompoundTag) getTag();
+        }
+        catch (ClassCastException e)
+        {
+            throw new InternalExpressionException(getString()+" is not a valid compound tag");
+        }
+    }
+
     public static class InventoryLocator
     {
         public Object owner;
@@ -195,4 +221,47 @@ public class NBTSerializableValue extends Value
             offset = o;
         }
     }
+
+    private static Map<String, NbtPathArgumentType.NbtPath> pathCache = new HashMap<>();
+    public static NbtPathArgumentType.NbtPath cachePath(String arg)
+    {
+        NbtPathArgumentType.NbtPath res = pathCache.get(arg);
+        if (res != null)
+            return res;
+        try
+        {
+            res = NbtPathArgumentType.nbtPath().method_9362(new StringReader(arg));
+        }
+        catch (CommandSyntaxException exc)
+        {
+            throw new InternalExpressionException("Incorrect nbt path: "+arg);
+        }
+        if (pathCache.size() > 1024)
+            pathCache.clear();
+        pathCache.put(arg, res);
+        return res;
+    }
+
+    @Override
+    public Value getElementAt(Value value)
+    {
+        NbtPathArgumentType.NbtPath path = cachePath(value.getString());
+        try
+        {
+            List<Tag> tags = path.get(getTag());
+            if (tags.size()==0)
+                return Value.NULL;
+            if (tags.size()==1)
+                return NBTSerializableValue.decodeTag(tags.get(0));
+            return ListValue.wrap(tags.stream().map(NBTSerializableValue::decodeTag).collect(Collectors.toList()));
+        }
+        catch (CommandSyntaxException ignored) { }
+        return Value.NULL;
+    }
+
+    @Override
+    public String getTypeString()
+    {
+        return "nbt";
+    }
 }

src/main/java/carpet/script/value/NullValue.java

@@ -38,4 +38,10 @@ public class NullValue extends NumericValue // TODO check nonsingleton code
     {
         return  o instanceof NullValue ? 0 : -1;
     }
+
+    @Override
+    public String getTypeString()
+    {
+        return "null";
+    }
 }

src/main/java/carpet/script/value/NumericValue.java

@@ -167,4 +167,10 @@ public class NumericValue extends Value
         return getLong();
     }
 
+    @Override
+    public String getTypeString()
+    {
+        return "number";
+    }
+
 }

src/main/java/carpet/script/value/StringValue.java

@@ -24,4 +24,10 @@ public class StringValue extends Value
     {
         this.str = str;
     }
+
+    @Override
+    public String getTypeString()
+    {
+        return "number";
+    }
 }

src/main/java/carpet/script/value/Value.java

@@ -172,4 +172,11 @@ public abstract class Value implements Comparable<Value>, Cloneable
     {
         return (long)readNumber();
     }
+
+    public Value getElementAt(Value v2)
+    {
+        throw new InternalExpressionException("get element can only be obtained for lists and nbt values");
+    }
+
+    public abstract String getTypeString();
 }

src/main/java/carpet/settings/CarpetSettings.java

@@ -211,6 +211,9 @@ public class CarpetSettings
     @Rule(desc = "Enables /player command to control/spawn players", category = COMMAND)
     public static boolean commandPlayer = true;
 
+    @Rule(desc = "Allows to track mobs AI via /track command", category = COMMAND)
+    public static boolean commandTrackAI = true;
+
     @Rule(desc = "Placing carpets may issue carpet commands for non-op players", category = SURVIVAL)
     public static boolean carpets = false;
 

src/main/java/carpet/utils/MobAI.java

@@ -0,0 +1,93 @@
+package carpet.utils;
+
+import carpet.CarpetServer;
+import com.google.common.collect.Sets;
+import net.minecraft.entity.Entity;
+import net.minecraft.entity.EntityType;
+import net.minecraft.server.world.ServerWorld;
+import net.minecraft.util.registry.Registry;
+
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+import java.util.stream.Collectors;
+
+public class MobAI
+{
+    private static Map<EntityType,Set<TrackingType>> aiTrackers = new HashMap<>();
+
+    public static void resetTrackers()
+    {
+        aiTrackers.clear();
+    }
+
+    public static boolean isTracking(Entity e, TrackingType type)
+    {
+        Set<TrackingType> currentTrackers = aiTrackers.get(e.getType());
+        if (currentTrackers == null)
+            return false;
+        return currentTrackers.contains(type);
+    }
+
+    public static void clearTracking(EntityType etype)
+    {
+        aiTrackers.remove(etype);
+        for(ServerWorld world : CarpetServer.minecraft_server.getWorlds() )
+        {
+            for (Entity e: world.getEntities(etype, Entity::hasCustomName))
+            {
+                e.setCustomNameVisible(false);
+                e.setCustomName(null);
+            }
+        }
+    }
+
+    public static void startTracking(EntityType e, TrackingType type)
+    {
+        aiTrackers.putIfAbsent(e,Sets.newHashSet());
+        aiTrackers.get(e).add(type);
+    }
+
+    public static List<String> availbleTypes()
+    {
+        Set<EntityType> types = new HashSet<>();
+        for (TrackingType type: TrackingType.values())
+        {
+            types.addAll(type.types);
+        }
+        return types.stream().map(t -> Registry.ENTITY_TYPE.getId(t).getPath()).collect(Collectors.toList());
+    }
+
+    public static List<String> availableFor(EntityType<?> entityType)
+    {
+        Set<TrackingType> availableOptions = new HashSet<>();
+        for (TrackingType type: TrackingType.values())
+            for (EntityType etype: type.types)
+                if (etype == entityType)
+                    availableOptions.add(type);
+        return availableOptions.stream().map(t -> t.name).collect(Collectors.toList());
+    }
+
+    public enum TrackingType
+    {
+        IRON_GOLEM_SPAWNING("iron_golem_spawning", Sets.newHashSet(EntityType.VILLAGER));
+        public Set<EntityType> types;
+        public String name;
+        TrackingType(String name, Set<EntityType> applicableTypes)
+        {
+            this.name = name;
+            types = applicableTypes;
+        }
+
+        public static TrackingType byName(String aspect)
+        {
+            for (TrackingType type: values())
+                if (type.name.equalsIgnoreCase(aspect))
+                    return type;
+            return null;
+        }
+    }
+
+}

src/main/resources/carpet.mixins.json

@@ -27,6 +27,8 @@
     "ServerWorld_unloadedEntityMixin",
     "MobEntity_leashMixin",
 
+    "VillagerEntity_aiMixin",
+
     "ServerWorld_fakePlayersMixin",
 
     "ServerPlayNetworkHandler_coreMixin",