From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: dfsek <dfsek@protonmail.com>
Date: Wed, 16 Sep 2020 01:12:29 -0700
Subject: [PATCH] Add StructuresLocateEvent

Co-authored-by: Jake Potrebic <jake.m.potrebic@gmail.com>

diff --git a/src/main/java/io/papermc/paper/registry/RegistryKey.java b/src/main/java/io/papermc/paper/registry/RegistryKey.java
index 6f39e343147803e15e7681c993b8797a629702e7..3a643d57b646c83974b5157b9cbb2a9f42e9bd59 100644
--- a/src/main/java/io/papermc/paper/registry/RegistryKey.java
+++ b/src/main/java/io/papermc/paper/registry/RegistryKey.java
@@ -1,8 +1,14 @@
 package io.papermc.paper.registry;
 
+import io.papermc.paper.world.structure.ConfiguredStructure;
 import net.minecraft.core.Registry;
+import net.minecraft.core.registries.Registries;
 import net.minecraft.resources.ResourceKey;
+import net.minecraft.world.level.levelgen.structure.Structure;
 import org.bukkit.Keyed;
 
 public record RegistryKey<API extends Keyed, MINECRAFT>(Class<API> apiClass, ResourceKey<? extends Registry<MINECRAFT>> resourceKey) {
+
+    public static final RegistryKey<ConfiguredStructure, Structure> CONFIGURED_STRUCTURE_REGISTRY = new RegistryKey<>(ConfiguredStructure.class, Registries.STRUCTURE);
+
 }
diff --git a/src/main/java/io/papermc/paper/world/structure/PaperConfiguredStructure.java b/src/main/java/io/papermc/paper/world/structure/PaperConfiguredStructure.java
new file mode 100644
index 0000000000000000000000000000000000000000..16996c743b169e625ec810523c1d59a305e1d159
--- /dev/null
+++ b/src/main/java/io/papermc/paper/world/structure/PaperConfiguredStructure.java
@@ -0,0 +1,44 @@
+package io.papermc.paper.world.structure;
+
+import io.papermc.paper.registry.PaperRegistry;
+import io.papermc.paper.registry.RegistryKey;
+import net.minecraft.core.Registry;
+import net.minecraft.core.registries.BuiltInRegistries;
+import net.minecraft.core.registries.Registries;
+import net.minecraft.resources.ResourceLocation;
+import net.minecraft.world.level.levelgen.structure.Structure;
+import org.bukkit.NamespacedKey;
+import org.bukkit.StructureType;
+import org.checkerframework.checker.nullness.qual.NonNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.framework.qual.DefaultQualifier;
+
+import java.util.Objects;
+import java.util.function.Supplier;
+
+@DefaultQualifier(NonNull.class)
+public final class PaperConfiguredStructure {
+
+    private PaperConfiguredStructure() {
+    }
+
+    public static void init() {
+        new ConfiguredStructureRegistry().register();
+    }
+
+    static final class ConfiguredStructureRegistry extends PaperRegistry<ConfiguredStructure, Structure> {
+
+        private static final Supplier<Registry<Structure>> STRUCTURE_FEATURE_REGISTRY = registryFor(Registries.STRUCTURE);
+
+        public ConfiguredStructureRegistry() {
+            super(RegistryKey.CONFIGURED_STRUCTURE_REGISTRY);
+        }
+
+        @Override
+        public @Nullable ConfiguredStructure convertToApi(NamespacedKey key, Structure nms) {
+            final ResourceLocation structureTypeLoc = Objects.requireNonNull(BuiltInRegistries.STRUCTURE_TYPE.getKey(nms.type()), "unexpected structure type " + nms.type());
+            final @Nullable StructureType structureType = StructureType.getStructureTypes().get(structureTypeLoc.getPath());
+            return structureType == null ? null : new ConfiguredStructure(key, structureType);
+        }
+    }
+}
diff --git a/src/main/java/net/minecraft/world/level/chunk/ChunkGenerator.java b/src/main/java/net/minecraft/world/level/chunk/ChunkGenerator.java
index b6df6077107759963ee8205dddb90501d5ccb4d6..29032374f0e71a41a2de260d402b6fbff68288cc 100644
--- a/src/main/java/net/minecraft/world/level/chunk/ChunkGenerator.java
+++ b/src/main/java/net/minecraft/world/level/chunk/ChunkGenerator.java
@@ -121,6 +121,26 @@ public abstract class ChunkGenerator {
 
     @Nullable
     public Pair<BlockPos, Holder<Structure>> findNearestMapStructure(ServerLevel world, HolderSet<Structure> structures, BlockPos center, int radius, boolean skipReferencedStructures) {
+        // Paper start - StructureLocateEvent
+        final org.bukkit.World bukkitWorld = world.getWorld();
+        final org.bukkit.Location origin = io.papermc.paper.util.MCUtil.toLocation(world, center);
+        final var paperRegistry = io.papermc.paper.registry.PaperRegistry.getRegistry(io.papermc.paper.registry.RegistryKey.CONFIGURED_STRUCTURE_REGISTRY);
+        final List<io.papermc.paper.world.structure.ConfiguredStructure> configuredStructures = new ArrayList<>();
+        paperRegistry.convertToApi(structures, configuredStructures::add, false); // gracefully handle missing api, use tests to check (or exclude)
+        if (!configuredStructures.isEmpty()) {
+            final io.papermc.paper.event.world.StructuresLocateEvent event = new io.papermc.paper.event.world.StructuresLocateEvent(bukkitWorld, origin, configuredStructures, radius, skipReferencedStructures);
+            if (!event.callEvent()) {
+                return null;
+            }
+            if (event.getResult() != null) {
+                return Pair.of(io.papermc.paper.util.MCUtil.toBlockPosition(event.getResult().position()), paperRegistry.getMinecraftHolder(event.getResult().configuredStructure()));
+            }
+            center = io.papermc.paper.util.MCUtil.toBlockPosition(event.getOrigin());
+            radius = event.getRadius();
+            skipReferencedStructures = event.shouldFindUnexplored();
+            structures = HolderSet.direct(paperRegistry::getMinecraftHolder, event.getConfiguredStructures());
+        }
+        // Paper end
         ChunkGeneratorStructureState chunkgeneratorstructurestate = world.getChunkSource().getGeneratorState();
         Map<StructurePlacement, Set<Holder<Structure>>> map = new Object2ObjectArrayMap();
         Iterator iterator = structures.iterator();
diff --git a/src/main/java/net/minecraft/world/level/levelgen/structure/Structure.java b/src/main/java/net/minecraft/world/level/levelgen/structure/Structure.java
index 8eaa1a57e904fe7e540b311c6c5c36b755f021fc..92730afcda6f779d0c440c7a8d50bb792b57d2d3 100644
--- a/src/main/java/net/minecraft/world/level/levelgen/structure/Structure.java
+++ b/src/main/java/net/minecraft/world/level/levelgen/structure/Structure.java
@@ -42,6 +42,7 @@ public abstract class Structure {
     public static final Codec<Structure> DIRECT_CODEC = BuiltInRegistries.STRUCTURE_TYPE.byNameCodec().dispatch(Structure::type, StructureType::codec);
     public static final Codec<Holder<Structure>> CODEC = RegistryFileCodec.create(Registries.STRUCTURE, DIRECT_CODEC);
     protected final Structure.StructureSettings settings;
+    static { io.papermc.paper.world.structure.PaperConfiguredStructure.init(); } // Paper
 
     public static <S extends Structure> RecordCodecBuilder<S, Structure.StructureSettings> settingsCodec(RecordCodecBuilder.Instance<S> instance) {
         return Structure.StructureSettings.CODEC.forGetter((feature) -> {
diff --git a/src/test/java/io/papermc/paper/world/structure/ConfiguredStructureTest.java b/src/test/java/io/papermc/paper/world/structure/ConfiguredStructureTest.java
new file mode 100644
index 0000000000000000000000000000000000000000..cb077ac5e24d6632c46927fef8ecd20f150d3596
--- /dev/null
+++ b/src/test/java/io/papermc/paper/world/structure/ConfiguredStructureTest.java
@@ -0,0 +1,95 @@
+package io.papermc.paper.world.structure;
+
+import io.papermc.paper.registry.Reference;
+import net.minecraft.core.Registry;
+import net.minecraft.core.registries.Registries;
+import net.minecraft.resources.ResourceKey;
+import net.minecraft.resources.ResourceLocation;
+import net.minecraft.server.Bootstrap;
+import net.minecraft.world.level.levelgen.structure.Structure;
+import net.minecraft.world.level.levelgen.structure.BuiltinStructures;
+import org.bukkit.NamespacedKey;
+import org.bukkit.craftbukkit.util.CraftNamespacedKey;
+import org.bukkit.support.AbstractTestingBase;
+import org.junit.AfterClass;
+import org.junit.BeforeClass;
+import org.junit.Test;
+
+import java.io.PrintStream;
+import java.lang.reflect.Field;
+import java.lang.reflect.Modifier;
+import java.util.LinkedHashMap;
+import java.util.Map;
+import java.util.StringJoiner;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertTrue;
+
+public class ConfiguredStructureTest extends AbstractTestingBase {
+
+    private static final Map<ResourceLocation, String> BUILT_IN_STRUCTURES = new LinkedHashMap<>();
+    private static final Map<NamespacedKey, Reference<?>> DEFAULT_CONFIGURED_STRUCTURES = new LinkedHashMap<>();
+
+    private static PrintStream out;
+
+    @BeforeClass
+    public static void collectStructures() throws ReflectiveOperationException {
+        out = System.out;
+        System.setOut(Bootstrap.STDOUT);
+        for (Field field : BuiltinStructures.class.getDeclaredFields()) {
+            if (field.getType().equals(ResourceKey.class) && Modifier.isStatic(field.getModifiers())) {
+                BUILT_IN_STRUCTURES.put(((ResourceKey<?>) field.get(null)).location(), field.getName());
+            }
+        }
+        for (Field field : ConfiguredStructure.class.getDeclaredFields()) {
+            if (field.getType().equals(Reference.class) && Modifier.isStatic(field.getModifiers())) {
+                final Reference<?> ref = (Reference<?>) field.get(null);
+                DEFAULT_CONFIGURED_STRUCTURES.put(ref.getKey(), ref);
+            }
+        }
+    }
+
+    @Test
+    public void testMinecraftToApi() {
+        Registry<Structure> structureRegistry = AbstractTestingBase.REGISTRY_CUSTOM.registryOrThrow(Registries.STRUCTURE);
+        assertEquals("configured structure maps should be the same size", BUILT_IN_STRUCTURES.size(), structureRegistry.size());
+
+        Map<ResourceLocation, Structure> missing = new LinkedHashMap<>();
+        for (Structure feature : structureRegistry) {
+            final ResourceLocation key = structureRegistry.getKey(feature);
+            assertNotNull("Missing built-in registry key", key);
+            if (key.equals(BuiltinStructures.ANCIENT_CITY.location())) {
+                continue; // TODO remove when upstream adds "jigsaw" StructureType
+            }
+            if (DEFAULT_CONFIGURED_STRUCTURES.get(CraftNamespacedKey.fromMinecraft(key)) == null) {
+                missing.put(key, feature);
+            }
+        }
+
+        assertTrue(printMissing(missing), missing.isEmpty());
+    }
+
+    @Test
+    public void testApiToMinecraft() {
+        Registry<Structure> structureRegistry = AbstractTestingBase.REGISTRY_CUSTOM.registryOrThrow(Registries.STRUCTURE);
+        for (NamespacedKey apiKey : DEFAULT_CONFIGURED_STRUCTURES.keySet()) {
+            assertTrue(apiKey + " does not have a minecraft counterpart", structureRegistry.containsKey(CraftNamespacedKey.toMinecraft(apiKey)));
+        }
+    }
+
+    private static String printMissing(Map<ResourceLocation, Structure> missing) {
+        final StringJoiner joiner = new StringJoiner("\n", "Missing: \n", "");
+
+        missing.forEach((key, configuredFeature) -> {
+            joiner.add("public static final Reference<ConfiguredStructure> " + BUILT_IN_STRUCTURES.get(key) + " = create(\"" + key.getPath() + "\");");
+        });
+
+        return joiner.toString();
+    }
+
+    @AfterClass
+    public static void after() {
+        System.setOut(out);
+    }
+}
