/*
 * 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.tracing;

import org.neo4j.kernel.impl.transaction.log.LogPosition;

/**
 * Represents the process of turning the state of a committing transaction into a sequence of commands, and appending
 * them to the transaction log.
 */
public interface LogAppendEvent extends LogForceEvents, LogRotateEvents, AutoCloseable {
    LogAppendEvent NULL = new Empty();

    /**
     * Notify about append of data into the current log file.
     * New data is appended to the end of the log file and located between {@code logPositionBeforeAppend} and {@code logPositionAfterAppend}
     * @param logPositionBeforeAppend start position
     * @param logPositionAfterAppend end position
     */
    void appendToLogFile(LogPosition logPositionBeforeAppend, LogPosition logPositionAfterAppend);

    /**
     * Mark the end of the process of appending a transaction to the transaction log.
     */
    @Override
    void close();

    /**
     * Note whether or not the log was rotated by the appending of this transaction to the log.
     */
    void setLogRotated(boolean logRotated);

    /**
     * Begin serializing and writing out the commands for this transaction.
     * @param appendItems number of items we desire to append
     */
    AppendTransactionEvent beginAppendTransaction(int appendItems);

    class Empty implements LogAppendEvent {
        @Override
        public void appendToLogFile(LogPosition logPositionBeforeAppend, LogPosition logPositionAfterAppend) {}

        @Override
        public void close() {}

        @Override
        public void setLogRotated(boolean logRotated) {}

        @Override
        public LogRotateEvent beginLogRotate() {
            return LogRotateEvent.NULL;
        }

        @Override
        public AppendTransactionEvent beginAppendTransaction(int appendItems) {
            return AppendTransactionEvent.NULL;
        }

        @Override
        public LogForceWaitEvent beginLogForceWait() {
            return LogForceWaitEvent.NULL;
        }

        @Override
        public LogForceEvent beginLogForce() {
            return LogForceEvent.NULL;
        }
    }
}
