package net.minecraft.network;

import io.netty.buffer.ByteBuf;

public class VarInt {
	public static final int MAX_VARINT_SIZE = 5;
	private static final int DATA_BITS_MASK = 127;
	private static final int CONTINUATION_BIT_MASK = 128;
	private static final int DATA_BITS_PER_BYTE = 7;

	public static int getByteSize(final int value) {
		for (int i = 1; i < 5; i++) {
			if ((value & -1 << i * 7) == 0) {
				return i;
			}
		}

		return 5;
	}

	public static boolean hasContinuationBit(final byte in) {
		return (in & 128) == 128;
	}

	public static int read(final ByteBuf input) {
		int out = 0;
		int bytes = 0;

		byte in;
		do {
			in = input.readByte();
			out |= (in & 127) << bytes++ * 7;
			if (bytes > 5) {
				throw new RuntimeException("VarInt too big");
			}
		} while (hasContinuationBit(in));

		return out;
	}

	public static ByteBuf write(final ByteBuf output, int value) {
		while ((value & -128) != 0) {
			output.writeByte(value & 127 | 128);
			value >>>= 7;
		}

		output.writeByte(value);
		return output;
	}
}