// This Source Code is in the Public Domain per: http://unlicense.org
package org.litesoft.sequences;

public interface SequenceSource {
    public void clearAllGroups();

    public void clear( String pGroup );

    public void preallocateNextSequenceNumbers( String pGroup, int pBlockSize, Long pRestartAt );

    public long getNextSequenceNumber( String pGroup, Long pRestartAt );

    public long getNextSequenceNumber( String pGroup );

    public long getNextSequenceNumber( Class pGroup );

    public static class Restart {
        public static boolean at( long pRetVal, Long pRestartAt ) {
            return (pRestartAt != null) && LLat( pRetVal, pRestartAt );
        }

        private static boolean LLat( long pRetVal, long pRestartAt ) {
            return (pRestartAt > 1) && (pRestartAt <= pRetVal);
        }
    }

    public static final SequenceSource NULL = new SequenceSource() {
        private long mLastNumber = 0;

        public void clearAllGroups() {
        }

        public void clear( String pGroup ) {
        }

        public void preallocateNextSequenceNumbers( String pGroup, int pBlockSize, Long pRestartAt ) {
        }

        public synchronized long getNextSequenceNumber( String pGroup, Long pRestartAt ) {
            long rv = ++mLastNumber;
            if ( Restart.at( rv, pRestartAt ) ) {
                rv = mLastNumber = 1;
            }
            return rv;
        }

        public long getNextSequenceNumber( String pGroup ) {
            return getNextSequenceNumber( pGroup, null );
        }

        public long getNextSequenceNumber( Class pGroup ) {
            return getNextSequenceNumber( pGroup.getName() );
        }
    };
}