/*

 * Copyright (c) 2007, 2011, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * This code 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

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

package com.sun.tools.javac.file;

import com.sun.tools.javac.file.RelativePath.RelativeDirectory;

import com.sun.tools.javac.util.Context;

import java.io.File;

import java.io.IOException;

import java.util.ArrayList;

import java.util.HashMap;

import java.util.Iterator;

import java.util.List;

import java.util.Map;

/** A cache for ZipFileIndex objects. */

public class ZipFileIndexCache {

    private final Map<File, ZipFileIndex> map =

            new HashMap<File, ZipFileIndex>();

    /** Get a shared instance of the cache. */

    private static ZipFileIndexCache sharedInstance;

    public synchronized static ZipFileIndexCache getSharedInstance() {

        if (sharedInstance == null)

            sharedInstance = new ZipFileIndexCache();

        return sharedInstance;

    }

    /** Get a context-specific instance of a cache. */

    public static ZipFileIndexCache instance(Context context) {

        ZipFileIndexCache instance = context.get(ZipFileIndexCache.class);

        if (instance == null)

            context.put(ZipFileIndexCache.class, instance = new ZipFileIndexCache());

        return instance;

    }

    /**

     * Returns a list of all ZipFileIndex entries

     *

     * @return A list of ZipFileIndex entries, or an empty list

     */

    public List<ZipFileIndex> getZipFileIndexes() {

        return getZipFileIndexes(false);

    }

    /**

     * Returns a list of all ZipFileIndex entries

     *

     * @param openedOnly If true it returns a list of only opened ZipFileIndex entries, otherwise

     *                   all ZipFileEntry(s) are included into the list.

     * @return A list of ZipFileIndex entries, or an empty list

     */

    public synchronized List<ZipFileIndex> getZipFileIndexes(boolean openedOnly) {

        List<ZipFileIndex> zipFileIndexes = new ArrayList<ZipFileIndex>();

        zipFileIndexes.addAll(map.values());

        if (openedOnly) {

            for(ZipFileIndex elem : zipFileIndexes) {

                if (!elem.isOpen()) {

                    zipFileIndexes.remove(elem);

                }

            }

        }

        return zipFileIndexes;

    }

    public synchronized ZipFileIndex getZipFileIndex(File zipFile,

            RelativeDirectory symbolFilePrefix,

            boolean useCache, String cacheLocation,

            boolean writeIndex) throws IOException {

        ZipFileIndex zi = getExistingZipIndex(zipFile);

        if (zi == null || (zi != null && zipFile.lastModified() != zi.zipFileLastModified)) {

            zi = new ZipFileIndex(zipFile, symbolFilePrefix, writeIndex,

                    useCache, cacheLocation);

            map.put(zipFile, zi);

        }

        return zi;

    }

    public synchronized ZipFileIndex getExistingZipIndex(File zipFile) {

        return map.get(zipFile);

    }

    public synchronized void clearCache() {

        map.clear();

    }

    public synchronized void clearCache(long timeNotUsed) {

        Iterator<File> cachedFileIterator = map.keySet().iterator();

        while (cachedFileIterator.hasNext()) {

            File cachedFile = cachedFileIterator.next();

            ZipFileIndex cachedZipIndex = map.get(cachedFile);

            if (cachedZipIndex != null) {

                long timeToTest = cachedZipIndex.lastReferenceTimeStamp + timeNotUsed;

                if (timeToTest < cachedZipIndex.lastReferenceTimeStamp || // Overflow...

                        System.currentTimeMillis() > timeToTest) {

                    map.remove(cachedFile);

                }

            }

        }

    }

    public synchronized void removeFromCache(File file) {

        map.remove(file);

    }

    /** Sets already opened list of ZipFileIndexes from an outside client

      * of the compiler. This functionality should be used in a non-batch clients of the compiler.

      */

    public synchronized void setOpenedIndexes(List<ZipFileIndex>indexes) throws IllegalStateException {

        if (map.isEmpty()) {

            String msg =

                    "Setting opened indexes should be called only when the ZipFileCache is empty. "

                    + "Call JavacFileManager.flush() before calling this method.";

            throw new IllegalStateException(msg);

        }

        for (ZipFileIndex zfi : indexes) {

            map.put(zfi.zipFile, zfi);

        }

    }

}