package com.mojang.blaze3d.vertex;

import com.google.common.primitives.Floats;
import it.unimi.dsi.fastutil.ints.IntArrays;
import org.joml.Vector3f;
import org.joml.Vector3fc;

public interface VertexSorting {
	VertexSorting DISTANCE_TO_ORIGIN = byDistance(0.0F, 0.0F, 0.0F);
	VertexSorting ORTHOGRAPHIC_Z = byDistance(point -> -point.z());

	static VertexSorting byDistance(final float x, final float y, final float z) {
		return byDistance(new Vector3f(x, y, z));
	}

	static VertexSorting byDistance(final Vector3fc origin) {
		return byDistance(origin::distanceSquared);
	}

	static VertexSorting byDistance(final VertexSorting.DistanceFunction function) {
		return values -> {
			Vector3f scratch = new Vector3f();
			float[] keys = new float[values.size()];
			int[] indices = new int[values.size()];

			for (int i = 0; i < values.size(); indices[i] = i++) {
				keys[i] = function.apply(values.get(i, scratch));
			}

			IntArrays.mergeSort(indices, (o1, o2) -> Floats.compare(keys[o2], keys[o1]));
			return indices;
		};
	}

	int[] sort(CompactVectorArray points);

	@FunctionalInterface
	public interface DistanceFunction {
		float apply(Vector3f value);
	}
}