minecraft-src/net/minecraft/world/entity/npc/WanderingTraderSpawner.java

package net.minecraft.world.entity.npc;

import java.util.Optional;
import net.minecraft.core.BlockPos;
import net.minecraft.server.level.ServerLevel;
import net.minecraft.tags.BiomeTags;
import net.minecraft.util.Mth;
import net.minecraft.util.RandomSource;
import net.minecraft.world.entity.EntitySpawnReason;
import net.minecraft.world.entity.EntityType;
import net.minecraft.world.entity.SpawnPlacementType;
import net.minecraft.world.entity.SpawnPlacements;
import net.minecraft.world.entity.ai.village.poi.PoiManager;
import net.minecraft.world.entity.ai.village.poi.PoiTypes;
import net.minecraft.world.entity.animal.horse.TraderLlama;
import net.minecraft.world.entity.player.Player;
import net.minecraft.world.level.BlockGetter;
import net.minecraft.world.level.CustomSpawner;
import net.minecraft.world.level.GameRules;
import net.minecraft.world.level.LevelReader;
import net.minecraft.world.level.levelgen.Heightmap;
import net.minecraft.world.level.storage.ServerLevelData;
import org.jetbrains.annotations.Nullable;

public class WanderingTraderSpawner implements CustomSpawner {
	private static final int DEFAULT_TICK_DELAY = 1200;
	public static final int DEFAULT_SPAWN_DELAY = 24000;
	private static final int MIN_SPAWN_CHANCE = 25;
	private static final int MAX_SPAWN_CHANCE = 75;
	private static final int SPAWN_CHANCE_INCREASE = 25;
	private static final int SPAWN_ONE_IN_X_CHANCE = 10;
	private static final int NUMBER_OF_SPAWN_ATTEMPTS = 10;
	private final RandomSource random = RandomSource.create();
	private final ServerLevelData serverLevelData;
	private int tickDelay;
	private int spawnDelay;
	private int spawnChance;

	public WanderingTraderSpawner(ServerLevelData serverLevelData) {
		this.serverLevelData = serverLevelData;
		this.tickDelay = 1200;
		this.spawnDelay = serverLevelData.getWanderingTraderSpawnDelay();
		this.spawnChance = serverLevelData.getWanderingTraderSpawnChance();
		if (this.spawnDelay == 0 && this.spawnChance == 0) {
			this.spawnDelay = 24000;
			serverLevelData.setWanderingTraderSpawnDelay(this.spawnDelay);
			this.spawnChance = 25;
			serverLevelData.setWanderingTraderSpawnChance(this.spawnChance);
		}
	}

	@Override
	public void tick(ServerLevel level, boolean spawnEnemies, boolean spawnFriendlies) {
		if (level.getGameRules().getBoolean(GameRules.RULE_DO_TRADER_SPAWNING)) {
			if (--this.tickDelay <= 0) {
				this.tickDelay = 1200;
				this.spawnDelay -= 1200;
				this.serverLevelData.setWanderingTraderSpawnDelay(this.spawnDelay);
				if (this.spawnDelay <= 0) {
					this.spawnDelay = 24000;
					if (level.getGameRules().getBoolean(GameRules.RULE_DOMOBSPAWNING)) {
						int i = this.spawnChance;
						this.spawnChance = Mth.clamp(this.spawnChance + 25, 25, 75);
						this.serverLevelData.setWanderingTraderSpawnChance(this.spawnChance);
						if (this.random.nextInt(100) <= i) {
							if (this.spawn(level)) {
								this.spawnChance = 25;
							}
						}
					}
				}
			}
		}
	}

	private boolean spawn(ServerLevel serverLevel) {
		Player player = serverLevel.getRandomPlayer();
		if (player == null) {
			return true;
		} else if (this.random.nextInt(10) != 0) {
			return false;
		} else {
			BlockPos blockPos = player.blockPosition();
			int i = 48;
			PoiManager poiManager = serverLevel.getPoiManager();
			Optional<BlockPos> optional = poiManager.find(holder -> holder.is(PoiTypes.MEETING), blockPosx -> true, blockPos, 48, PoiManager.Occupancy.ANY);
			BlockPos blockPos2 = (BlockPos)optional.orElse(blockPos);
			BlockPos blockPos3 = this.findSpawnPositionNear(serverLevel, blockPos2, 48);
			if (blockPos3 != null && this.hasEnoughSpace(serverLevel, blockPos3)) {
				if (serverLevel.getBiome(blockPos3).is(BiomeTags.WITHOUT_WANDERING_TRADER_SPAWNS)) {
					return false;
				}

				WanderingTrader wanderingTrader = EntityType.WANDERING_TRADER.spawn(serverLevel, blockPos3, EntitySpawnReason.EVENT);
				if (wanderingTrader != null) {
					for (int j = 0; j < 2; j++) {
						this.tryToSpawnLlamaFor(serverLevel, wanderingTrader, 4);
					}

					this.serverLevelData.setWanderingTraderId(wanderingTrader.getUUID());
					wanderingTrader.setDespawnDelay(48000);
					wanderingTrader.setWanderTarget(blockPos2);
					wanderingTrader.setHomeTo(blockPos2, 16);
					return true;
				}
			}

			return false;
		}
	}

	private void tryToSpawnLlamaFor(ServerLevel serverLevel, WanderingTrader trader, int maxDistance) {
		BlockPos blockPos = this.findSpawnPositionNear(serverLevel, trader.blockPosition(), maxDistance);
		if (blockPos != null) {
			TraderLlama traderLlama = EntityType.TRADER_LLAMA.spawn(serverLevel, blockPos, EntitySpawnReason.EVENT);
			if (traderLlama != null) {
				traderLlama.setLeashedTo(trader, true);
			}
		}
	}

	@Nullable
	private BlockPos findSpawnPositionNear(LevelReader level, BlockPos pos, int maxDistance) {
		BlockPos blockPos = null;
		SpawnPlacementType spawnPlacementType = SpawnPlacements.getPlacementType(EntityType.WANDERING_TRADER);

		for (int i = 0; i < 10; i++) {
			int j = pos.getX() + this.random.nextInt(maxDistance * 2) - maxDistance;
			int k = pos.getZ() + this.random.nextInt(maxDistance * 2) - maxDistance;
			int l = level.getHeight(Heightmap.Types.WORLD_SURFACE, j, k);
			BlockPos blockPos2 = new BlockPos(j, l, k);
			if (spawnPlacementType.isSpawnPositionOk(level, blockPos2, EntityType.WANDERING_TRADER)) {
				blockPos = blockPos2;
				break;
			}
		}

		return blockPos;
	}

	private boolean hasEnoughSpace(BlockGetter level, BlockPos pos) {
		for (BlockPos blockPos : BlockPos.betweenClosed(pos, pos.offset(1, 2, 1))) {
			if (!level.getBlockState(blockPos).getCollisionShape(level, blockPos).isEmpty()) {
				return false;
			}
		}

		return true;
	}
}