package edu.uci.ics.hyracks.dataflow.common.data.normalizers;

import edu.uci.ics.hyracks.api.dataflow.value.INormalizedKeyComputer;
import edu.uci.ics.hyracks.api.dataflow.value.INormalizedKeyComputerFactory;
import edu.uci.ics.hyracks.dataflow.common.data.marshalling.Integer64SerializerDeserializer;

public class Integer64NormalizedKeyComputerFactory implements INormalizedKeyComputerFactory {

    private static final long serialVersionUID = 8735044913496854551L;

    @Override
    public INormalizedKeyComputer createNormalizedKeyComputer() {
        return new INormalizedKeyComputer() {
            private static final int POSTIVE_LONG_MASK = (3 << 30);
            private static final int NON_NEGATIVE_INT_MASK = (2 << 30);
            private static final int NEGATIVE_LONG_MASK = (0 << 30);

            @Override
            public int normalize(byte[] bytes, int start, int length) {
                long value = Integer64SerializerDeserializer.getLong(bytes, start);
                int highValue = (int) (value >> 32);
                if (highValue > 0) {
                    /**
                     * larger than Integer.MAX
                     */
                    int highNmk = getKey(highValue);
                    highNmk >>= 2;
                    highNmk |= POSTIVE_LONG_MASK;
                    return highNmk;
                } else if (highValue == 0) {
                    /**
                     * smaller than Integer.MAX but >=0
                     */
                    int lowNmk = (int) value;
                    lowNmk >>= 2;
                    lowNmk |= NON_NEGATIVE_INT_MASK;
                    return lowNmk;
                } else {
                    /**
                     * less than 0: have not optimized for that
                     */
                    int highNmk = getKey(highValue);
                    highNmk >>= 2;
                    highNmk |= NEGATIVE_LONG_MASK;
                    return highNmk;
                }
            }

            private int getKey(int value) {
                return value ^ Integer.MIN_VALUE;
            }

        };
    }
}