package net.minecraft.world.level.levelgen;

import com.google.common.annotations.VisibleForTesting;
import java.util.concurrent.atomic.AtomicLong;
import net.minecraft.util.Mth;
import net.minecraft.util.RandomSource;
import net.minecraft.util.ThreadingDetector;

public class LegacyRandomSource implements BitRandomSource {
	private static final int MODULUS_BITS = 48;
	private static final long MODULUS_MASK = 281474976710655L;
	private static final long MULTIPLIER = 25214903917L;
	private static final long INCREMENT = 11L;
	private final AtomicLong seed = new AtomicLong();
	private final MarsagliaPolarGaussian gaussianSource = new MarsagliaPolarGaussian(this);

	public LegacyRandomSource(final long seed) {
		this.setSeed(seed);
	}

	@Override
	public RandomSource fork() {
		return new LegacyRandomSource(this.nextLong());
	}

	@Override
	public PositionalRandomFactory forkPositional() {
		return new LegacyRandomSource.LegacyPositionalRandomFactory(this.nextLong());
	}

	@Override
	public void setSeed(final long seed) {
		if (!this.seed.compareAndSet(this.seed.get(), (seed ^ 25214903917L) & 281474976710655L)) {
			throw ThreadingDetector.makeThreadingException("LegacyRandomSource", null);
		} else {
			this.gaussianSource.reset();
		}
	}

	@Override
	public int next(final int bits) {
		long oldSeed = this.seed.get();
		long newSeed = oldSeed * 25214903917L + 11L & 281474976710655L;
		if (!this.seed.compareAndSet(oldSeed, newSeed)) {
			throw ThreadingDetector.makeThreadingException("LegacyRandomSource", null);
		} else {
			return (int)(newSeed >> 48 - bits);
		}
	}

	@Override
	public double nextGaussian() {
		return this.gaussianSource.nextGaussian();
	}

	public static class LegacyPositionalRandomFactory implements PositionalRandomFactory {
		private final long seed;

		public LegacyPositionalRandomFactory(final long seed) {
			this.seed = seed;
		}

		@Override
		public RandomSource at(final int x, final int y, final int z) {
			long positionalSeed = Mth.getSeed(x, y, z);
			long randomSeed = positionalSeed ^ this.seed;
			return new LegacyRandomSource(randomSeed);
		}

		@Override
		public RandomSource fromHashOf(final String name) {
			int positionalSeed = name.hashCode();
			return new LegacyRandomSource(positionalSeed ^ this.seed);
		}

		@Override
		public RandomSource fromSeed(final long seed) {
			return new LegacyRandomSource(seed);
		}

		@VisibleForTesting
		@Override
		public void parityConfigString(final StringBuilder sb) {
			sb.append("LegacyPositionalRandomFactory{").append(this.seed).append("}");
		}
	}
}