package net.minecraft.world.level.levelgen;

import java.util.function.LongFunction;
import net.minecraft.util.RandomSource;

public class WorldgenRandom extends LegacyRandomSource {
	private final RandomSource randomSource;
	private int count;

	public WorldgenRandom(RandomSource randomSource) {
		super(0L);
		this.randomSource = randomSource;
	}

	public int getCount() {
		return this.count;
	}

	@Override
	public RandomSource fork() {
		return this.randomSource.fork();
	}

	@Override
	public PositionalRandomFactory forkPositional() {
		return this.randomSource.forkPositional();
	}

	@Override
	public int next(int size) {
		this.count++;
		return this.randomSource instanceof LegacyRandomSource legacyRandomSource ? legacyRandomSource.next(size) : (int)(this.randomSource.nextLong() >>> 64 - size);
	}

	@Override
	public synchronized void setSeed(long seed) {
		if (this.randomSource != null) {
			this.randomSource.setSeed(seed);
		}
	}

	/**
	 * Seeds the current random for chunk decoration, including spawning mobs and for use in feature placement.
	 * The coordinates correspond to the minimum block position within a given chunk.
	 */
	public long setDecorationSeed(long levelSeed, int minChunkBlockX, int minChunkBlockZ) {
		this.setSeed(levelSeed);
		long l = this.nextLong() | 1L;
		long m = this.nextLong() | 1L;
		long n = minChunkBlockX * l + minChunkBlockZ * m ^ levelSeed;
		this.setSeed(n);
		return n;
	}

	/**
	 * Seeds the current random for placing features.
	 * Each feature is seeded differently in order to seem more random. However, it does not do a good job of this, and issues can arise from the salt being small with features that have the same decoration step and are close together in the feature lists.
	 * 
	 * @param decorationSeed The seed computed by {@link #setDecorationSeed(long, int, int)}
	 * @param index The cumulative index of the generating feature within the biome's list of features.
	 * @param decorationStep The ordinal of the {@link net.minecraft.world.level.levelgen.GenerationStep.Decoration} of the generating feature.
	 */
	public void setFeatureSeed(long decorationSeed, int index, int decorationStep) {
		long l = decorationSeed + index + 10000 * decorationStep;
		this.setSeed(l);
	}

	/**
	 * Seeds the current random for placing large features such as caves, strongholds, and mineshafts.
	 * 
	 * @param baseSeed This is passed in as the level seed, or in some cases such as carvers, as an offset from the level seed unique to each carver.
	 */
	public void setLargeFeatureSeed(long baseSeed, int chunkX, int chunkZ) {
		this.setSeed(baseSeed);
		long l = this.nextLong();
		long m = this.nextLong();
		long n = chunkX * l ^ chunkZ * m ^ baseSeed;
		this.setSeed(n);
	}

	/**
	 * Seeds the current random for placing the starts of structure features.
	 * The region coordinates are the region which the target chunk lies in. For example, witch hut regions are 32x32 chunks, so all chunks within that region would be seeded identically.
	 * The size of the regions themselves are determined by the {@code spacing} of the structure settings.
	 * 
	 * @param salt A salt unique to each structure.
	 */
	public void setLargeFeatureWithSalt(long levelSeed, int regionX, int regionZ, int salt) {
		long l = regionX * 341873128712L + regionZ * 132897987541L + levelSeed + salt;
		this.setSeed(l);
	}

	/**
	 * Creates a new {@code RandomSource}, seeded for determining whether a chunk is a slime chunk or not.
	 * 
	 * @param salt For vanilla slimes, this is always {@code 987234911L}
	 */
	public static RandomSource seedSlimeChunk(int chunkX, int chunkZ, long levelSeed, long salt) {
		return RandomSource.create(levelSeed + chunkX * chunkX * 4987142 + chunkX * 5947611 + chunkZ * chunkZ * 4392871L + chunkZ * 389711 ^ salt);
	}

	public static enum Algorithm {
		LEGACY(LegacyRandomSource::new),
		XOROSHIRO(XoroshiroRandomSource::new);

		private final LongFunction<RandomSource> constructor;

		private Algorithm(final LongFunction<RandomSource> constructor) {
			this.constructor = constructor;
		}

		public RandomSource newInstance(long seed) {
			return (RandomSource)this.constructor.apply(seed);
		}
	}
}