/*

 * Copyright 2007-2008 Sun Microsystems, Inc.  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.  Sun designates this

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

 * by Sun 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

 * CA 95054 USA or visit www.sun.com if you need additional information or

 * have any questions.

 */

package com.sun.tools.javac.file;

import java.io.File;

import java.io.FileNotFoundException;

import java.io.IOException;

import java.io.RandomAccessFile;

import java.lang.ref.SoftReference;

import java.util.ArrayList;

import java.util.Arrays;

import java.util.Calendar;

import java.util.Collections;

import java.util.HashMap;

import java.util.HashSet;

import java.util.Iterator;

import java.util.List;

import java.util.Map;

import java.util.Set;

import java.util.concurrent.locks.ReentrantLock;

import java.util.zip.DataFormatException;

import java.util.zip.Inflater;

import java.util.zip.ZipException;

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

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

/** This class implements building of index of a zip archive and access to it's context.

 *  It also uses prebuild index if available. It supports invocations where it will

 *  serialize an optimized zip index file to disk.

 *

 *  In oreder to use secondary index file make sure the option "usezipindex" is in the Options object,

 *  when JavacFileManager is invoked. (You can pass "-XDusezipindex" on the command line.

 *

 *  Location where to look for/generate optimized zip index files can be provided using

 *  "-XDcachezipindexdir=<directory>". If this flag is not provided, the dfault location is

 *  the value of the "java.io.tmpdir" system property.

 *

 *  If key "-XDwritezipindexfiles" is specified, there will be new optimized index file

 *  created for each archive, used by the compiler for compilation, at location,

 *  specified by "cachezipindexdir" option.

 *

 * If nonBatchMode option is specified (-XDnonBatchMode) the compiler will use timestamp

 * checking to reindex the zip files if it is needed. In batch mode the timestamps are not checked

 * and the compiler uses the cached indexes.

 *

 * <p><b>This is NOT part of any API supported by Sun Microsystems.

 * If you write code that depends on this, you do so at your own risk.

 * This code and its internal interfaces are subject to change or

 * deletion without notice.</b>

 */

public class ZipFileIndex {

    private static final String MIN_CHAR = String.valueOf(Character.MIN_VALUE);

    private static final String MAX_CHAR = String.valueOf(Character.MAX_VALUE);

    public final static long NOT_MODIFIED = Long.MIN_VALUE;

    private static Map<File, ZipFileIndex> zipFileIndexCache = new HashMap<File, ZipFileIndex>();

    private static ReentrantLock lock = new ReentrantLock();

    private static boolean NON_BATCH_MODE = System.getProperty("nonBatchMode") != null;// TODO: Use -XD compiler switch for this.

    private Map<RelativeDirectory, DirectoryEntry> directories = Collections.<RelativeDirectory, DirectoryEntry>emptyMap();

    private Set<RelativeDirectory> allDirs = Collections.<RelativeDirectory>emptySet();

    // ZipFileIndex data entries

    private File zipFile;

    private long zipFileLastModified = NOT_MODIFIED;

    private RandomAccessFile zipRandomFile;

    private Entry[] entries;

    private boolean readFromIndex = false;

    private File zipIndexFile = null;

    private boolean triedToReadIndex = false;

    final RelativeDirectory symbolFilePrefix;

    private int symbolFilePrefixLength = 0;

    private boolean hasPopulatedData = false;

    private long lastReferenceTimeStamp = NOT_MODIFIED;

    private boolean usePreindexedCache = false;

    private String preindexedCacheLocation = null;

    private boolean writeIndex = false;

    private Map <String, SoftReference<RelativeDirectory>> relativeDirectoryCache =

            new HashMap<String, SoftReference<RelativeDirectory>>();

    /**

     * Returns a list of all ZipFileIndex entries

     *

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

     */

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

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

        lock.lock();

        try {

            zipFileIndexes.addAll(zipFileIndexCache.values());

            if (openedOnly) {

                for(ZipFileIndex elem : zipFileIndexes) {

                    if (!elem.isOpen()) {

                        zipFileIndexes.remove(elem);

                    }

                }

            }

        }

        finally {

            lock.unlock();

        }

        return zipFileIndexes;

    }

    public boolean isOpen() {

        lock.lock();

        try {

            return zipRandomFile != null;

        }

        finally {

            lock.unlock();

        }

    }

    public static ZipFileIndex getZipFileIndex(File zipFile,

            RelativeDirectory symbolFilePrefix,

            boolean useCache, String cacheLocation,

            boolean writeIndex) throws IOException {

        ZipFileIndex zi = null;

        lock.lock();

        try {

            zi = getExistingZipIndex(zipFile);

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

                zi = new ZipFileIndex(zipFile, symbolFilePrefix, writeIndex,

                        useCache, cacheLocation);

                zipFileIndexCache.put(zipFile, zi);

            }

        }

        finally {

            lock.unlock();

        }

        return zi;

    }

    public static ZipFileIndex getExistingZipIndex(File zipFile) {

        lock.lock();

        try {

            return zipFileIndexCache.get(zipFile);

        }

        finally {

            lock.unlock();

        }

    }

    public static void clearCache() {

        lock.lock();

        try {

            zipFileIndexCache.clear();

        }

        finally {

            lock.unlock();

        }

    }

    public static void clearCache(long timeNotUsed) {

        lock.lock();

        try {

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

            while (cachedFileIterator.hasNext()) {

                File cachedFile = cachedFileIterator.next();

                ZipFileIndex cachedZipIndex = zipFileIndexCache.get(cachedFile);

                if (cachedZipIndex != null) {

                    long timeToTest = cachedZipIndex.lastReferenceTimeStamp + timeNotUsed;

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

                            System.currentTimeMillis() > timeToTest) {

                        zipFileIndexCache.remove(cachedFile);

                    }

                }

            }

        }

        finally {

            lock.unlock();

        }

    }

    public static void removeFromCache(File file) {

        lock.lock();

        try {

            zipFileIndexCache.remove(file);

        }

        finally {

            lock.unlock();

        }

    }

    /** 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 static void setOpenedIndexes(List<ZipFileIndex>indexes) throws IllegalStateException {

        lock.lock();

        try {

            if (zipFileIndexCache.isEmpty()) {

                throw new IllegalStateException("Setting opened indexes should be called only when the ZipFileCache is empty. Call JavacFileManager.flush() before calling this method.");

            }

            for (ZipFileIndex zfi : indexes) {

                zipFileIndexCache.put(zfi.zipFile, zfi);

            }

        }

        finally {

            lock.unlock();

        }

    }

    private ZipFileIndex(File zipFile, RelativeDirectory symbolFilePrefix, boolean writeIndex,

            boolean useCache, String cacheLocation) throws IOException {

        this.zipFile = zipFile;

        this.symbolFilePrefix = symbolFilePrefix;

        this.symbolFilePrefixLength = (symbolFilePrefix == null ? 0 :

            symbolFilePrefix.getPath().getBytes("UTF-8").length);

        this.writeIndex = writeIndex;

        this.usePreindexedCache = useCache;

        this.preindexedCacheLocation = cacheLocation;

        if (zipFile != null) {

            this.zipFileLastModified = zipFile.lastModified();

        }

        // Validate integrity of the zip file

        checkIndex();

    }

    public String toString() {

        return "ZipFileIndex[" + zipFile + "]";

    }

    // Just in case...

    protected void finalize() {

        closeFile();

    }

    private boolean isUpToDate() {

        if (zipFile != null &&

                ((!NON_BATCH_MODE) || zipFileLastModified == zipFile.lastModified()) &&

                hasPopulatedData) {

            return true;

        }

        return false;

    }

    /**

     * Here we need to make sure that the ZipFileIndex is valid. Check the timestamp of the file and

     * if its the same as the one at the time the index was build we don't need to reopen anything.

     */

    private void checkIndex() throws IOException {

        boolean isUpToDate = true;

        if (!isUpToDate()) {

            closeFile();

            isUpToDate = false;

        }

        if (zipRandomFile != null || isUpToDate) {

            lastReferenceTimeStamp = System.currentTimeMillis();

            return;

        }

        hasPopulatedData = true;

        if (readIndex()) {

            lastReferenceTimeStamp = System.currentTimeMillis();

            return;

        }

        directories = Collections.<RelativeDirectory, DirectoryEntry>emptyMap();

        allDirs = Collections.<RelativeDirectory>emptySet();

        try {

            openFile();

            long totalLength = zipRandomFile.length();

            ZipDirectory directory = new ZipDirectory(zipRandomFile, 0L, totalLength, this);

            directory.buildIndex();

        } finally {

            if (zipRandomFile != null) {

                closeFile();

            }

        }

        lastReferenceTimeStamp = System.currentTimeMillis();

    }

    private void openFile() throws FileNotFoundException {

        if (zipRandomFile == null && zipFile != null) {

            zipRandomFile = new RandomAccessFile(zipFile, "r");

        }

    }

    private void cleanupState() {

        // Make sure there is a valid but empty index if the file doesn't exist

        entries = Entry.EMPTY_ARRAY;

        directories = Collections.<RelativeDirectory, DirectoryEntry>emptyMap();

        zipFileLastModified = NOT_MODIFIED;

        allDirs = Collections.<RelativeDirectory>emptySet();

    }

    public void close() {

        lock.lock();

        try {

            writeIndex();

            closeFile();

        }

        finally {

            lock.unlock();

        }

    }

    private void closeFile() {

        if (zipRandomFile != null) {

            try {

                zipRandomFile.close();

            } catch (IOException ex) {

            }

            zipRandomFile = null;

        }

    }

    /**

     * Returns the ZipFileIndexEntry for an absolute path, if there is one.

     */

    Entry getZipIndexEntry(RelativePath path) {

        lock.lock();

        try {

            checkIndex();

            DirectoryEntry de = directories.get(path.dirname());

            String lookFor = path.basename();

            return de == null ? null : de.getEntry(lookFor);

        }

        catch (IOException e) {

            return null;

        }

        finally {

            lock.unlock();

        }

    }

    /**

     * Returns a javac List of filenames within an absolute path in the ZipFileIndex.

     */

    public com.sun.tools.javac.util.List<String> getFiles(RelativeDirectory path) {

        lock.lock();

        try {

            checkIndex();

            DirectoryEntry de = directories.get(path);

            com.sun.tools.javac.util.List<String> ret = de == null ? null : de.getFiles();

            if (ret == null) {

                return com.sun.tools.javac.util.List.<String>nil();

            }

            return ret;

        }

        catch (IOException e) {

            return com.sun.tools.javac.util.List.<String>nil();

        }

        finally {

            lock.unlock();

        }

    }

    public List<String> getDirectories(RelativeDirectory path) {

        lock.lock();

        try {

            checkIndex();

            DirectoryEntry de = directories.get(path);

            com.sun.tools.javac.util.List<String> ret = de == null ? null : de.getDirectories();

            if (ret == null) {

                return com.sun.tools.javac.util.List.<String>nil();

            }

            return ret;

        }

        catch (IOException e) {

            return com.sun.tools.javac.util.List.<String>nil();

        }

        finally {

            lock.unlock();

        }

    }

    public Set<RelativeDirectory> getAllDirectories() {

        lock.lock();

        try {

            checkIndex();

            if (allDirs == Collections.EMPTY_SET) {

                allDirs = new HashSet<RelativeDirectory>(directories.keySet());

            }

            return allDirs;

        }

        catch (IOException e) {

            return Collections.<RelativeDirectory>emptySet();

        }

        finally {

            lock.unlock();

        }

    }

    /**

     * Tests if a specific path exists in the zip.  This method will return true

     * for file entries and directories.

     *

     * @param path A path within the zip.

     * @return True if the path is a file or dir, false otherwise.

     */

    public boolean contains(RelativePath path) {

        lock.lock();

        try {

            checkIndex();

            return getZipIndexEntry(path) != null;

        }

        catch (IOException e) {

            return false;

        }

        finally {

            lock.unlock();

        }

    }

    public boolean isDirectory(RelativePath path) throws IOException {

        lock.lock();

        try {

            // The top level in a zip file is always a directory.

            if (path.getPath().length() == 0) {

                lastReferenceTimeStamp = System.currentTimeMillis();

                return true;

            }

            checkIndex();

            return directories.get(path) != null;

        }

        finally {

            lock.unlock();

        }

    }

    public long getLastModified(RelativeFile path) throws IOException {

        lock.lock();

        try {

            Entry entry = getZipIndexEntry(path);

            if (entry == null)

                throw new FileNotFoundException();

            return entry.getLastModified();

        }

        finally {

            lock.unlock();

        }

    }

    public int length(RelativeFile path) throws IOException {

        lock.lock();

        try {

            Entry entry = getZipIndexEntry(path);

            if (entry == null)

                throw new FileNotFoundException();

            if (entry.isDir) {

                return 0;

            }

            byte[] header = getHeader(entry);

            // entry is not compressed?

            if (get2ByteLittleEndian(header, 8) == 0) {

                return entry.compressedSize;

            } else {

                return entry.size;

            }

        }

        finally {

            lock.unlock();