package com.destroystokyo.paper.antixray;

import io.netty.buffer.ByteBuf;

public class DataBitsReader {

    private ByteBuf dataBits; // Akarin
    private int bitsPerValue;
    private int mask;
    private int longInDataBitsIndex;
    private int bitInLongIndex;
    private long current;

    public void setDataBits(ByteBuf dataBits) { // Akarin
        this.dataBits = dataBits;
    }

    public void setBitsPerValue(int bitsPerValue) {
        this.bitsPerValue = bitsPerValue;
        mask = (1 << bitsPerValue) - 1;
    }

    public void setIndex(int index) {
        this.longInDataBitsIndex = index;
        bitInLongIndex = 0;
        init();
    }

    private void init() {
        if (dataBits.capacity() > longInDataBitsIndex + 7) { // Akarin
            // Akarin start
            dataBits.getLong(longInDataBitsIndex);
            /*
            current = ((((long) dataBits[longInDataBitsIndex]) << 56)
                    | (((long) dataBits[longInDataBitsIndex + 1] & 0xff) << 48)
                    | (((long) dataBits[longInDataBitsIndex + 2] & 0xff) << 40)
                    | (((long) dataBits[longInDataBitsIndex + 3] & 0xff) << 32)
                    | (((long) dataBits[longInDataBitsIndex + 4] & 0xff) << 24)
                    | (((long) dataBits[longInDataBitsIndex + 5] & 0xff) << 16)
                    | (((long) dataBits[longInDataBitsIndex + 6] & 0xff) << 8)
                    | (((long) dataBits[longInDataBitsIndex + 7] & 0xff)));
            */ // Akarin end
        }
    }

    public int read() {
        int value = (int) (current >>> bitInLongIndex) & mask;
        bitInLongIndex += bitsPerValue;

        if (bitInLongIndex > 63) {
            bitInLongIndex -= 64;
            longInDataBitsIndex += 8;
            init();

            if (bitInLongIndex > 0) {
                value |= current << bitsPerValue - bitInLongIndex & mask;
            }
        }

        return value;
    }
}