/*
 * 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.kernel.impl.transaction.log;

import static org.neo4j.util.Preconditions.requireNonNegative;

public class LogPosition implements Comparable<LogPosition> {
    public static final LogPosition UNSPECIFIED = new UnspecifiedLogPosition();

    private final long logVersion;
    private final long byteOffset;

    // Only used to construct restricted UNSPECIFIED instance
    private LogPosition() {
        logVersion = -1L;
        byteOffset = -1L;
    }

    public LogPosition(long logVersion, long byteOffset) {
        this.logVersion = requireNonNegative(logVersion);
        this.byteOffset = requireNonNegative(byteOffset);
    }

    public long getLogVersion() {
        return logVersion;
    }

    public long getByteOffset() {
        return byteOffset;
    }

    @Override
    public String toString() {
        return "LogPosition{" + "logVersion=" + logVersion + ", byteOffset=" + byteOffset + '}';
    }

    @Override
    public boolean equals(Object o) {
        if (this == o) {
            return true;
        }
        if (o == null || getClass() != o.getClass()) {
            return false;
        }

        LogPosition that = (LogPosition) o;
        return byteOffset == that.byteOffset && logVersion == that.logVersion;
    }

    @Override
    public int hashCode() {
        int result = (int) (logVersion ^ (logVersion >>> 32));
        result = 31 * result + (int) (byteOffset ^ (byteOffset >>> 32));
        return result;
    }

    @Override
    public int compareTo(LogPosition o) {
        if (logVersion != o.logVersion) {
            return Long.compare(logVersion, o.logVersion);
        }
        return Long.compare(byteOffset, o.byteOffset);
    }

    private static final class UnspecifiedLogPosition extends LogPosition {
        @Override
        public long getLogVersion() {
            throw new UnsupportedOperationException();
        }

        @Override
        public long getByteOffset() {
            throw new UnsupportedOperationException();
        }

        @Override
        public String toString() {
            return "UNSPECIFIED";
        }
    }
}
