package edu.uci.ics.hivesterix.runtime.factory.normalize;

import edu.uci.ics.hivesterix.serde.lazy.LazyUtils;
import edu.uci.ics.hivesterix.serde.lazy.LazyUtils.VInt;
import edu.uci.ics.hyracks.api.dataflow.value.INormalizedKeyComputer;
import edu.uci.ics.hyracks.api.dataflow.value.INormalizedKeyComputerFactory;
import edu.uci.ics.hyracks.data.std.primitive.UTF8StringPointable;

public class HiveStringDescNormalizedKeyComputerFactory implements
		INormalizedKeyComputerFactory {

	private static final long serialVersionUID = 1L;

	@Override
	public INormalizedKeyComputer createNormalizedKeyComputer() {
		return new INormalizedKeyComputer() {
			private VInt len = new VInt();

			@Override
			public int normalize(byte[] bytes, int start, int length) {
				LazyUtils.readVInt(bytes, start, len);
				if (len.value + len.length != length)
					throw new IllegalStateException(
							"parse string: length mismatch, expected "
									+ (len.value + len.length) + " but get "
									+ length);
				int nk = 0;
				int offset = start + len.length;
				for (int i = 0; i < 2; ++i) {
					nk <<= 16;
					if (i < len.value) {
						nk += ((int) UTF8StringPointable.charAt(bytes, offset)) & 0xffff;
						offset += UTF8StringPointable.charSize(bytes, offset);
					}
				}
				return (int) ((long) 0xffffffff - (long) nk);
			}
		};
	}
}