package net.minecraft.network;

import io.netty.buffer.ByteBuf;
import net.minecraft.util.Mth;
import net.minecraft.world.phys.Vec3;

public class LpVec3 {
	private static final int DATA_BITS = 15;
	private static final int DATA_BITS_MASK = 32767;
	private static final double MAX_QUANTIZED_VALUE = 32766.0;
	private static final int SCALE_BITS = 2;
	private static final int SCALE_BITS_MASK = 3;
	private static final int CONTINUATION_FLAG = 4;
	private static final int X_OFFSET = 3;
	private static final int Y_OFFSET = 18;
	private static final int Z_OFFSET = 33;
	public static final double ABS_MAX_VALUE = 1.7179869183E10;
	public static final double ABS_MIN_VALUE = 3.051944088384301E-5;

	public static boolean hasContinuationBit(final int in) {
		return (in & 4) == 4;
	}

	public static Vec3 read(final ByteBuf input) {
		int lowest = input.readUnsignedByte();
		if (lowest == 0) {
			return Vec3.ZERO;
		} else {
			int middle = input.readUnsignedByte();
			long highest = input.readUnsignedInt();
			long buffer = highest << 16 | middle << 8 | lowest;
			long scale = lowest & 3;
			if (hasContinuationBit(lowest)) {
				scale |= (VarInt.read(input) & 4294967295L) << 2;
			}

			return new Vec3(unpack(buffer >> 3) * scale, unpack(buffer >> 18) * scale, unpack(buffer >> 33) * scale);
		}
	}

	public static void write(final ByteBuf output, final Vec3 value) {
		double x = sanitize(value.x);
		double y = sanitize(value.y);
		double z = sanitize(value.z);
		double chessboardLength = Mth.absMax(x, Mth.absMax(y, z));
		if (chessboardLength < 3.051944088384301E-5) {
			output.writeByte(0);
		} else {
			long scale = Mth.ceilLong(chessboardLength);
			boolean isPartial = (scale & 3L) != scale;
			long markers = isPartial ? scale & 3L | 4L : scale;
			long xn = pack(x / scale) << 3;
			long yn = pack(y / scale) << 18;
			long zn = pack(z / scale) << 33;
			long buffer = markers | xn | yn | zn;
			output.writeByte((byte)buffer);
			output.writeByte((byte)(buffer >> 8));
			output.writeInt((int)(buffer >> 16));
			if (isPartial) {
				VarInt.write(output, (int)(scale >> 2));
			}
		}
	}

	private static double sanitize(final double value) {
		return Double.isNaN(value) ? 0.0 : Math.clamp(value, -1.7179869183E10, 1.7179869183E10);
	}

	private static long pack(final double value) {
		return Math.round((value * 0.5 + 0.5) * 32766.0);
	}

	private static double unpack(final long value) {
		return Math.min(value & 32767L, 32766.0) * 2.0 / 32766.0 - 1.0;
	}
}