/*
 * Copyright (c) "Neo4j"
 * Neo4j Sweden AB [http://neo4j.com]
 *
 * This file is part of Neo4j.
 *
 * Neo4j is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
package org.neo4j.internal.batchimport;

/**
 * Common and cross-concern utilities.
 */
public class Utils {
    public enum CompareType {
        EQ,
        GT,
        GE,
        LT,
        LE,
        NE
    }

    public static boolean unsignedCompare(
            long dataA, long dataB, CompareType compareType) { // works for signed and unsigned values
        switch (compareType) {
            case EQ:
                return dataA == dataB;
            case GE:
                if (dataA == dataB) {
                    return true;
                }
                // fall through to GT
            case GT:
                return dataA < dataB == ((dataA < 0) != (dataB < 0));
            case LE:
                if (dataA == dataB) {
                    return true;
                }
                // fall through to LT
            case LT:
                return (dataA < dataB) ^ ((dataA < 0) != (dataB < 0));
            case NE:
                return false;

            default:
                throw new IllegalArgumentException("Unknown compare type: " + compareType);
        }
    }

    /**
     * Like {@link #unsignedCompare(long, long, CompareType)} but reversed in that you get {@link CompareType}
     * from comparing data A and B, i.e. the difference between them.
     */
    public static CompareType unsignedDifference(long dataA, long dataB) {
        if (dataA == dataB) {
            return CompareType.EQ;
        }
        return ((dataA < dataB) ^ ((dataA < 0) != (dataB < 0))) ? CompareType.LT : CompareType.GT;
    }

    // Values in the arrays are assumed to be sorted
    public static boolean anyIdCollides(long[] first, int firstLength, long[] other, int otherLength) {
        int f = 0;
        int o = 0;
        while (f < firstLength && o < otherLength) {
            if (first[f] == other[o]) {
                return true;
            }

            if (first[f] < other[o]) {
                while (++f < firstLength && first[f] < other[o]) {}
            } else {
                while (++o < otherLength && first[f] > other[o]) {}
            }
        }

        return false;
    }

    public static void mergeSortedInto(long[] values, long[] into, int intoLengthBefore) {
        int v = values.length - 1;
        int i = intoLengthBefore - 1;
        int t = i + values.length;
        while (v >= 0 || i >= 0) {
            if (i == -1) {
                into[t--] = values[v--];
            } else if (v == -1) {
                into[t--] = into[i--];
            } else if (values[v] >= into[i]) {
                into[t--] = values[v--];
            } else {
                into[t--] = into[i--];
            }
        }
    }

    private Utils() { // No instances allowed
    }
}
