implement stronghold hack on 1.19 bukkit

platforms/bukkit/nms/v1_19_R1/src/main/java/com/dfsek/terra/bukkit/nms/v1_19_R1/NMSChunkGeneratorDelegate.java

@@ -1,12 +1,20 @@
 package com.dfsek.terra.bukkit.nms.v1_19_R1;
 
+import com.mojang.datafixers.util.Pair;
 import com.mojang.serialization.Codec;
+import it.unimi.dsi.fastutil.objects.Object2ObjectArrayMap;
 import net.minecraft.core.BlockPos;
+import net.minecraft.core.Holder;
+import net.minecraft.core.HolderSet;
+import net.minecraft.core.SectionPos;
 import net.minecraft.server.level.WorldGenRegion;
+import net.minecraft.util.RandomSource;
+import net.minecraft.world.level.ChunkPos;
 import net.minecraft.world.level.LevelHeightAccessor;
 import net.minecraft.world.level.NoiseColumn;
 import net.minecraft.world.level.StructureManager;
 import net.minecraft.world.level.WorldGenLevel;
+import net.minecraft.world.level.biome.Biome;
 import net.minecraft.world.level.biome.BiomeManager;
 import net.minecraft.world.level.block.state.BlockState;
 import net.minecraft.world.level.chunk.ChunkAccess;
@@ -15,20 +23,33 @@ import net.minecraft.world.level.levelgen.GenerationStep.Carving;
 import net.minecraft.world.level.levelgen.Heightmap.Types;
 import net.minecraft.world.level.levelgen.RandomState;
 import net.minecraft.world.level.levelgen.blending.Blender;
+import net.minecraft.world.level.levelgen.structure.Structure;
+import net.minecraft.world.level.levelgen.structure.StructureSet;
+import net.minecraft.world.level.levelgen.structure.StructureSet.StructureSelectionEntry;
+import net.minecraft.world.level.levelgen.structure.placement.ConcentricRingsStructurePlacement;
 import org.bukkit.craftbukkit.v1_19_R1.block.data.CraftBlockData;
 import org.jetbrains.annotations.NotNull;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
+import java.util.ArrayList;
 import java.util.List;
+import java.util.Map;
+import java.util.Objects;
 import java.util.Optional;
+import java.util.Set;
 import java.util.concurrent.CompletableFuture;
 import java.util.concurrent.Executor;
+import java.util.stream.Stream;
 
 import com.dfsek.terra.api.config.ConfigPack;
+import com.dfsek.terra.api.util.generic.Lazy;
 import com.dfsek.terra.api.world.biome.generation.BiomeProvider;
 import com.dfsek.terra.api.world.info.WorldProperties;
 
 
 public class NMSChunkGeneratorDelegate extends ChunkGenerator {
+    private static final Logger LOGGER = LoggerFactory.getLogger(NMSChunkGeneratorDelegate.class);
     private final com.dfsek.terra.api.world.chunk.generation.ChunkGenerator delegate;
     
     private final ChunkGenerator vanilla;
@@ -56,12 +77,14 @@ public class NMSChunkGeneratorDelegate extends ChunkGenerator {
     }
     
     @Override
-    public void buildSurface(@NotNull WorldGenRegion region, @NotNull StructureManager structures, @NotNull RandomState noiseConfig, @NotNull ChunkAccess chunk) {
+    public void buildSurface(@NotNull WorldGenRegion region, @NotNull StructureManager structures, @NotNull RandomState noiseConfig,
+                             @NotNull ChunkAccess chunk) {
         // no-op
     }
     
     @Override
-    public void applyBiomeDecoration(@NotNull WorldGenLevel world, @NotNull ChunkAccess chunk, @NotNull StructureManager structureAccessor) {
+    public void applyBiomeDecoration(@NotNull WorldGenLevel world, @NotNull ChunkAccess chunk,
+                                     @NotNull StructureManager structureAccessor) {
         vanilla.applyBiomeDecoration(world, chunk, structureAccessor);
     }
     
@@ -76,7 +99,8 @@ public class NMSChunkGeneratorDelegate extends ChunkGenerator {
     }
     
     @Override
-    public @NotNull CompletableFuture<ChunkAccess> fillFromNoise(@NotNull Executor executor, @NotNull Blender blender, @NotNull RandomState noiseConfig,
+    public @NotNull CompletableFuture<ChunkAccess> fillFromNoise(@NotNull Executor executor, @NotNull Blender blender,
+                                                                 @NotNull RandomState noiseConfig,
                                                                  @NotNull StructureManager structureAccessor, @NotNull ChunkAccess chunk) {
         return vanilla.fillFromNoise(executor, blender, noiseConfig, structureAccessor, chunk);
     }
@@ -119,4 +143,99 @@ public class NMSChunkGeneratorDelegate extends ChunkGenerator {
     public void addDebugScreenInfo(@NotNull List<String> text, @NotNull RandomState noiseConfig, @NotNull BlockPos pos) {
     
     }
+    
+    private volatile boolean rings = false;
+    private final Map<ConcentricRingsStructurePlacement, Lazy<List<ChunkPos>>> ringPositions = new Object2ObjectArrayMap<>();
+    
+    @Override
+    public void ensureStructuresGenerated(@NotNull RandomState noiseConfig) {
+        if(!this.rings) {
+            super.ensureStructuresGenerated(noiseConfig);
+            this.populateStrongholdData(noiseConfig);
+            this.rings = true;
+        }
+        
+    }
+    
+    @Override
+    public List<ChunkPos> getRingPositionsFor(@NotNull ConcentricRingsStructurePlacement structurePlacement, @NotNull RandomState noiseConfig) {
+        ensureStructuresGenerated(noiseConfig);
+        return ringPositions.get(structurePlacement).value();
+    }
+    
+    private void populateStrongholdData(RandomState noiseConfig) {
+        LOGGER.info("Generating safe stronghold data. This may take up to a minute.");
+        Set<Holder<Biome>> set = this.biomeSource.possibleBiomes();
+        possibleStructureSets().map(Holder::value).forEach((holder) -> {
+            boolean match = false;
+            for(StructureSelectionEntry structureset_a : holder.structures()) {
+                Structure structure = structureset_a.structure().value();
+                Stream<Holder<Biome>> stream = structure.biomes().stream();
+                if(stream.anyMatch(set::contains)) {
+                    match = true;
+                }
+            }
+            
+            if (match) {
+                if (holder.placement() instanceof ConcentricRingsStructurePlacement concentricringsstructureplacement) {
+                    this.ringPositions.put(concentricringsstructureplacement, Lazy.lazy(() -> this.generateRingPositions(holder, noiseConfig, concentricringsstructureplacement)));
+                }
+            }
+        });
+    }
+    private List<ChunkPos> generateRingPositions(StructureSet holder, RandomState randomstate,
+                                                 ConcentricRingsStructurePlacement concentricringsstructureplacement) { // Spigot
+        if(concentricringsstructureplacement.count() == 0) {
+            return List.of();
+        }
+        
+        List<ChunkPos> list = new ArrayList<>();
+        int i = concentricringsstructureplacement.distance();
+        int j = concentricringsstructureplacement.count();
+        int k = concentricringsstructureplacement.spread();
+        HolderSet<Biome> holderset = concentricringsstructureplacement.preferredBiomes();
+        RandomSource randomsource = RandomSource.create();
+        
+        if(this.conf.strongholdSeed != null && this.structureSets.getResourceKey(holder).orElse(null) ==
+                                               net.minecraft.world.level.levelgen.structure.BuiltinStructureSets.STRONGHOLDS) {
+            randomsource.setSeed(this.conf.strongholdSeed);
+        } else {
+            randomsource.setSeed(randomstate.legacyLevelSeed());
+        }
+        double d0 = randomsource.nextDouble() * 3.141592653589793D * 2.0D;
+        int l = 0;
+        int i1 = 0;
+        
+        for(int j1 = 0; j1 < j; ++j1) {
+            double d1 = (double) (4 * i + i * i1 * 6) + (randomsource.nextDouble() - 0.5D) * (double) i * 2.5D;
+            int k1 = (int) Math.round(Math.cos(d0) * d1);
+            int l1 = (int) Math.round(Math.sin(d0) * d1);
+            int i2 = SectionPos.sectionToBlockCoord(k1, 8);
+            int j2 = SectionPos.sectionToBlockCoord(l1, 8);
+            
+            Objects.requireNonNull(holderset);
+            Pair<BlockPos, Holder<Biome>> pair = this.biomeSource.findBiomeHorizontal(i2, 0, j2, 112, holderset::contains, randomsource,
+                                                                                      randomstate.sampler());
+            
+            if(pair != null) {
+                BlockPos blockposition = pair.getFirst();
+                
+                k1 = SectionPos.blockToSectionCoord(blockposition.getX());
+                l1 = SectionPos.blockToSectionCoord(blockposition.getZ());
+            }
+            
+            list.add(new ChunkPos(k1, l1));
+            d0 += 6.283185307179586D / (double) k;
+            ++l;
+            if(l == k) {
+                ++i1;
+                l = 0;
+                k += 2 * k / (i1 + 1);
+                k = Math.min(k, j - j1);
+                d0 += randomsource.nextDouble() * 3.141592653589793D * 2.0D;
+            }
+        }
+        
+        return list;
+    }
 }