/*
 * #%L
 * Alfresco Repository
 * %%
 * Copyright (C) 2005 - 2016 Alfresco Software Limited
 * %%
 * This file is part of the Alfresco software. 
 * If the software was purchased under a paid Alfresco license, the terms of 
 * the paid license agreement will prevail.  Otherwise, the software is 
 * provided under the following open source license terms:
 * 
 * Alfresco 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 3 of the License, or
 * (at your option) any later version.
 * 
 * Alfresco 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 Alfresco. If not, see <http://www.gnu.org/licenses/>.
 * #L%
 */
package org.alfresco.repo.search.impl.lucene.index;

import java.io.IOException;
import java.util.Map;

import org.springframework.context.ApplicationListener;

/**
 * An interface that exposes information about a Lucene Index and that allows registration of a listener for event
 * notifications.
 * 
 * @author dward
 */
public interface IndexMonitor
{
    /**
     * Gets the relative path of the index directory.
     * 
     * @return the relative path
     */
    public String getRelativePath();

    /**
     * Gets a snapshot of the statuses of the individual entries in this index.
     * 
     * @return a map of entry status names to entry counts
     */
    public Map<String, Integer> getStatusSnapshot();

    /**
     * Gets the actual size of the index in bytes.
     * 
     * @return the actual size in bytes
     * @throws IOException
     *             Signals that an I/O exception has occurred.
     */
    public long getActualSize() throws IOException;

    /**
     * Gets the size used on disk by the index directory. A large discrepancy from the value returned by
     * {@link #getActualSize()} may indicate that there are unused data files.
     * 
     * @return the size on disk in bytes
     * @throws IOException
     *             Signals that an I/O exception has occurred.
     */
    public long getUsedSize() throws IOException;

    /**
     * Gets the number of documents in the index.
     * 
     * @return the number of documents
     * @throws IOException
     *             Signals that an I/O exception has occurred.
     */
    public int getNumberOfDocuments() throws IOException;

    /**
     * Gets the number of fields known to the index.
     * 
     * @return the number of fields
     * @throws IOException
     *             Signals that an I/O exception has occurred.
     */
    public int getNumberOfFields() throws IOException;

    /**
     * Gets the number of indexed fields.
     * 
     * @return the number of indexed fields
     * @throws IOException
     *             Signals that an I/O exception has occurred.
     */
    public int getNumberOfIndexedFields() throws IOException;

    /**
     * Registers a listener for events on this index.
     * 
     * @param listener
     *            the listener
     */
    public void addApplicationListener(ApplicationListener listener);
}
