feat: command to list dropless mobs

src/main/java/com/hollingsworth/arsnouveau/common/command/DroplessMobsCommand.java

@@ -0,0 +1,98 @@
+package com.hollingsworth.arsnouveau.common.command;
+
+import com.hollingsworth.arsnouveau.api.ANFakePlayer;
+import com.mojang.brigadier.CommandDispatcher;
+import com.mojang.brigadier.arguments.IntegerArgumentType;
+import it.unimi.dsi.fastutil.objects.ObjectArrayList;
+import net.minecraft.commands.CommandSourceStack;
+import net.minecraft.commands.Commands;
+import net.minecraft.core.registries.BuiltInRegistries;
+import net.minecraft.network.chat.Component;
+import net.minecraft.server.ReloadableServerRegistries;
+import net.minecraft.server.level.ServerLevel;
+import net.minecraft.world.damagesource.DamageSource;
+import net.minecraft.world.entity.Entity;
+import net.minecraft.world.entity.EntityType;
+import net.minecraft.world.entity.LivingEntity;
+import net.minecraft.world.item.ItemStack;
+import net.minecraft.world.level.storage.loot.LootParams;
+import net.minecraft.world.level.storage.loot.LootTable;
+import net.minecraft.world.level.storage.loot.parameters.LootContextParamSets;
+import net.minecraft.world.level.storage.loot.parameters.LootContextParams;
+
+import java.util.stream.Collectors;
+
+public class DroplessMobsCommand {
+    public static void register(CommandDispatcher<CommandSourceStack> dispatcher) {
+        dispatcher.register(Commands.literal("ars-dropless").executes(c -> {
+            // The root command is accessible to everyone as it isn't too expensive to run.
+            c.getSource().sendSystemMessage(Component.literal(listDroplessEntities(c.getSource().getServer().reloadableRegistries(), c.getSource().getLevel(), 0).stream().map(e -> BuiltInRegistries.ENTITY_TYPE.getKey(e).toString()).collect(Collectors.joining(","))));
+            c.getSource().sendSystemMessage(Component.literal("Listed mobs that produce no drops under naive filtering, open your logs if you want to copy them."));
+
+            return 1;
+        }).then(Commands.literal("simulate").requires(c -> c.hasPermission(2)).then(Commands.argument("times", IntegerArgumentType.integer(1)).executes(c -> {
+            // This subcommand requires op as with enough simulations and entity types, it can get quite slow.
+            int times = IntegerArgumentType.getInteger(c, "times");
+            c.getSource().sendSystemMessage(Component.literal(listDroplessEntities(c.getSource().getServer().reloadableRegistries(), c.getSource().getLevel(), times).stream().map(e -> BuiltInRegistries.ENTITY_TYPE.getKey(e).toString()).collect(Collectors.joining(","))));
+            c.getSource().sendSystemMessage(Component.literal("Listed mobs that produced no drops after " + times +  " simulations, open your logs if you want to copy them."));
+
+            return 1;
+        }))));
+    }
+
+    public static ObjectArrayList<EntityType<?>> listDroplessEntities(ReloadableServerRegistries.Holder registries, ServerLevel level, int simulations) {
+        ANFakePlayer fakePlayer = simulations <= 0 ? null : ANFakePlayer.getPlayer(level);
+        DamageSource damageSource = simulations <= 0 ? null : level.damageSources().playerAttack(fakePlayer);
+        ObjectArrayList<ItemStack> stacks = simulations <= 0 ? null : new ObjectArrayList<>();
+
+        ObjectArrayList<EntityType<?>> types = new ObjectArrayList<>();
+        outer: for (EntityType<?> ty : BuiltInRegistries.ENTITY_TYPE) {
+            Entity e;
+            try {
+                e = ty.create(level);
+                if (e == null) {
+                    continue;
+                }
+
+                if (!(e instanceof LivingEntity)) {
+                    e.discard();
+                    continue;
+                }
+            } catch (Throwable ignored) {
+                continue;
+            }
+
+            LootTable table = registries.getLootTable(e.getType().getDefaultLootTable());
+            if (!table.pools.isEmpty()) {
+                e.discard();
+                continue;
+            }
+
+            if (simulations <= 0) {
+                types.add(e.getType());
+                continue;
+            }
+
+            LootParams.Builder ctx = (new LootParams.Builder(level))
+                    .withParameter(LootContextParams.THIS_ENTITY, e).withParameter(LootContextParams.ORIGIN, e.position())
+                    .withParameter(LootContextParams.DAMAGE_SOURCE, damageSource)
+                    .withOptionalParameter(LootContextParams.ATTACKING_ENTITY, fakePlayer)
+                    .withOptionalParameter(LootContextParams.DIRECT_ATTACKING_ENTITY, damageSource.getDirectEntity());
+            ctx = ctx.withParameter(LootContextParams.LAST_DAMAGE_PLAYER, fakePlayer)
+                    .withLuck(fakePlayer.getLuck());
+
+            for (int i = 0; i < simulations; i++) {
+                stacks.clear();
+                stacks.addAll(table.getRandomItems(ctx.create(LootContextParamSets.ENTITY)));
+                if (!stacks.isEmpty()) {
+                    e.discard();
+                    continue outer;
+                }
+            }
+
+            types.add(e.getType());
+        }
+
+        return types;
+    }
+}

src/main/java/com/hollingsworth/arsnouveau/common/event/EventHandler.java

@@ -344,6 +344,7 @@ public static void commandRegister(RegisterCommandsEvent event) {
         SummonAnimHeadCommand.register(event.getDispatcher());
         LearnGlyphCommand.register(event.getDispatcher());
         AdoptCommand.register(event.getDispatcher());
+        DroplessMobsCommand.register(event.getDispatcher());
     }
 
     @SubscribeEvent

src/main/resources/META-INF/accesstransformer.cfg

@@ -66,6 +66,7 @@ public net.minecraft.world.entity.Entity maxUpStep # maxUpStep
 public net.minecraft.world.level.levelgen.feature.stateproviders.BlockStateProviderType <init>(Lcom/mojang/serialization/MapCodec;)V # BlockStateProviderType
 public net.minecraft.world.item.crafting.RecipeManager byKeyTyped(Lnet/minecraft/world/item/crafting/RecipeType;Lnet/minecraft/resources/ResourceLocation;)Lnet/minecraft/world/item/crafting/RecipeHolder; # byKeyTyped
 public net.minecraft.client.multiplayer.ClientChunkCache$Storage chunks # chunks
+public net.minecraft.world.level.storage.loot.LootTable pools # pools
 # Geckolib ATs, do not delete
 public net.minecraft.client.model.geom.ModelPart$Cube
 public net.minecraft.client.model.geom.ModelPart cubes # cubes