From 53080bea06daddef5d1776be08568ef20770c838 Mon Sep 17 00:00:00 2001
From: Frank <developer@ambertation.de>
Date: Fri, 26 Nov 2021 16:22:32 +0100
Subject: [PATCH] new `SpawnAPI`

---
 src/main/java/ru/bclib/api/SpawnAPI.java | 126 +++++++++++++++++++++++
 1 file changed, 126 insertions(+)
 create mode 100644 src/main/java/ru/bclib/api/SpawnAPI.java

diff --git a/src/main/java/ru/bclib/api/SpawnAPI.java b/src/main/java/ru/bclib/api/SpawnAPI.java
new file mode 100644
index 00000000..dff43bdb
--- /dev/null
+++ b/src/main/java/ru/bclib/api/SpawnAPI.java
@@ -0,0 +1,126 @@
+package ru.bclib.api;
+
+import net.minecraft.core.BlockPos;
+import net.minecraft.world.Difficulty;
+import net.minecraft.world.entity.Entity;
+import net.minecraft.world.entity.EntityType;
+import net.minecraft.world.entity.MobSpawnType;
+import net.minecraft.world.level.LevelAccessor;
+import net.minecraft.world.level.block.state.BlockState;
+import net.minecraft.world.phys.AABB;
+import ru.bclib.util.BlocksHelper;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Random;
+
+
+public class SpawnAPI<T extends Entity> {
+	@FunctionalInterface
+	public interface SpawnRule<E extends Entity> {
+		boolean test(EntityType<? extends E> type, LevelAccessor world, MobSpawnType spawnReason, BlockPos pos, Random random);
+	}
+	
+	public interface IsBlock{
+		boolean is(BlockState state);
+	}
+	
+	private Class<T> entityClass;
+	public SpawnAPI(Class<T> entityClass){
+		this.entityClass = entityClass;
+	}
+	
+	ArrayList<SpawnRule<T>> rules = new ArrayList<>();
+	
+	public SpawnAPI<T> notPeaceful() {
+		rules.add((type, world, spawnReason, pos, random) -> world.getDifficulty() != Difficulty.PEACEFUL);
+		return this;
+	}
+	
+	public SpawnAPI<T> notPeacefulBelowBrightness() {
+		return notPeacefulBelowBrightness(7);
+	}
+	
+	public SpawnAPI<T> notPeacefulBelowBrightness(int bright) {
+		rules.add((type, world, spawnReason, pos, random) -> world.getDifficulty() != Difficulty.PEACEFUL && world.getMaxLocalRawBrightness(pos) <= bright);
+		return this;
+	}
+	
+	public SpawnAPI<T> belowBrightness() {
+		return belowBrightness(7);
+	}
+	
+	public SpawnAPI<T> belowBrightness(int bright) {
+		rules.add((type, world, spawnReason, pos, random) -> world.getMaxLocalRawBrightness(pos) <= bright);
+		return this;
+	}
+	
+	public SpawnAPI<T> belowMinHeight() {
+		rules.add((type, world, spawnReason, pos, random) -> pos.getY() < world.dimensionType().minY());
+		return this;
+	}
+	
+	public SpawnAPI<T> maxAlive(){
+		return maxAlive(4, 256);
+	}
+	
+	public SpawnAPI<T> maxAlive(int count){
+		return maxAlive(count, 256);
+	}
+	
+	public SpawnAPI<T> maxAlive(int count, int size){
+		rules.add((type, world, spawnReason, pos, random) -> {
+			try {
+				final AABB box = new AABB(pos).inflate(size, 256, size);
+				final List<T> list = world.getEntitiesOfClass(entityClass, box, (entity) -> true);
+				return list.size() < count;
+			}
+			catch (Exception e) {
+				return true;
+			}
+		});
+		return this;
+	}
+	
+	public SpawnAPI<T> maxHeight(int height) {
+		rules.add((type, world, spawnReason, pos, random) -> {
+			int h = BlocksHelper.downRay(world, pos, height+1);
+			return h<=height;
+		});
+		return this;
+	}
+	
+	public SpawnAPI<T> notAboveBlock(IsBlock blockTest, int height) {
+		rules.add((type, world, spawnReason, pos, random) -> {
+			int h = BlocksHelper.downRay(world, pos, height+1);
+			if  (h>height) return false;
+			
+			for (int i = 1; i <= h; i++)
+				if (blockTest.is(world.getBlockState(pos.below(i))))
+					return false;
+				
+			return true;
+		});
+		return this;
+	}
+	
+	public SpawnAPI<T> aboveBlock(IsBlock blockTest, int height) {
+		rules.add((type, world, spawnReason, pos, random) -> {
+			int h = BlocksHelper.downRay(world, pos, height+1);
+			if  (h>height) return false;
+			
+			for (int i = 1; i <= h; i++)
+				if (blockTest.is(world.getBlockState(pos.below(i))))
+					return true;
+			
+			return false;
+		});
+		return this;
+	}
+	
+	public boolean canSpawn(EntityType<? extends T> type, LevelAccessor world, MobSpawnType spawnReason, BlockPos pos, Random random) {
+		return rules.stream()
+					.map(r -> r.test(type, world, spawnReason, pos, random))
+					.reduce(true, (p, c) -> p && c);
+	}
+}