package net.minecraft.world.level.chunk.storage;

import com.google.common.annotations.VisibleForTesting;
import it.unimi.dsi.fastutil.ints.IntArraySet;
import it.unimi.dsi.fastutil.ints.IntCollection;
import it.unimi.dsi.fastutil.ints.IntSet;
import java.util.BitSet;

public class RegionBitmap {
	private final BitSet used = new BitSet();

	public void force(final int position, final int size) {
		this.used.set(position, position + size);
	}

	public void free(final int position, final int size) {
		this.used.clear(position, position + size);
	}

	public int allocate(final int size) {
		int current = 0;

		while (true) {
			int freeStart = this.used.nextClearBit(current);
			int freeEnd = this.used.nextSetBit(freeStart);
			if (freeEnd == -1 || freeEnd - freeStart >= size) {
				this.force(freeStart, size);
				return freeStart;
			}

			current = freeEnd;
		}
	}

	@VisibleForTesting
	public IntSet getUsed() {
		return (IntSet)this.used.stream().collect(IntArraySet::new, IntCollection::add, IntCollection::addAll);
	}
}