package net.minecraft.world.phys.shapes;

import it.unimi.dsi.fastutil.doubles.AbstractDoubleList;
import it.unimi.dsi.fastutil.doubles.DoubleList;

public class NonOverlappingMerger extends AbstractDoubleList implements IndexMerger {
	private final DoubleList lower;
	private final DoubleList upper;
	private final boolean swap;

	protected NonOverlappingMerger(final DoubleList lower, final DoubleList upper, final boolean swap) {
		this.lower = lower;
		this.upper = upper;
		this.swap = swap;
	}

	@Override
	public int size() {
		return this.lower.size() + this.upper.size();
	}

	@Override
	public boolean forMergedIndexes(final IndexMerger.IndexConsumer consumer) {
		return this.swap
			? this.forNonSwappedIndexes((firstIndex, secondIndex, resultIndex) -> consumer.merge(secondIndex, firstIndex, resultIndex))
			: this.forNonSwappedIndexes(consumer);
	}

	private boolean forNonSwappedIndexes(final IndexMerger.IndexConsumer consumer) {
		int lowerSize = this.lower.size();

		for (int i = 0; i < lowerSize; i++) {
			if (!consumer.merge(i, -1, i)) {
				return false;
			}
		}

		int upperSize = this.upper.size() - 1;

		for (int ix = 0; ix < upperSize; ix++) {
			if (!consumer.merge(lowerSize - 1, ix, lowerSize + ix)) {
				return false;
			}
		}

		return true;
	}

	@Override
	public double getDouble(final int index) {
		return index < this.lower.size() ? this.lower.getDouble(index) : this.upper.getDouble(index - this.lower.size());
	}

	@Override
	public DoubleList getList() {
		return this;
	}
}