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/*
 * eXist-db Open Source Native XML Database
 * Copyright (C) 2001 The eXist-db Authors
 *
 * [email protected]
 * http://www.exist-db.org
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 */
package org.exist.util;

import org.apache.logging.log4j.Logger;

import java.util.ArrayList;
import java.util.List;

/**
 * Represents a traceable history of state changes
 *
 * @param  Information about the state which was modified
 * @param  the change which was applied to the state
 *
 * @author Adam Retter
 */
public class TraceableStateChanges {
    private List> stateChangeTrace = new ArrayList<>();

    /**
     * Add a state change to the tail.
     *
     * @param stateChange the state change
     */
    public void add(final TraceableStateChange stateChange) {
        stateChangeTrace.add(stateChange);
    }

    /**
     * Clear all state changes
     */
    public void clear() {
        stateChangeTrace.clear();
    }

    /**
     * Makes a copy of the list of state changes
     * useful for archival purposes
     *
     * @return A copy of the state changes
     */
    @Override
    public Object clone() throws CloneNotSupportedException {
        final TraceableStateChanges copy = new TraceableStateChanges<>();
        copy.stateChangeTrace = new ArrayList<>(stateChangeTrace);
        return copy;
    }

    /**
     * Writes the history fo state changes to the
     * provided logger at TRACE level
     *
     * @param logger The logger to write the changes to
     */
    public final void logTrace(final Logger logger) {
        if (!logger.isTraceEnabled()) {
            throw new IllegalStateException("This is only enabled at TRACE level logging");
        }

        for (int i = 0; i < stateChangeTrace.size(); i++) {
            final TraceableStateChange traceableStateChange = stateChangeTrace.get(i);
            logger.trace("{}: {}: {}({}) from: {}({})",
                    i + 1,
                    traceableStateChange.getId(),
                    traceableStateChange.getChange(),
                    traceableStateChange.describeState(),
                    traceableStateChange.getThread(),
                    Stacktrace.asString(traceableStateChange.getTrace()));
        }
    }
}