/*

 * Copyright (c) 2007, 2012, 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 java.io.File;

import java.io.FileNotFoundException;

import java.io.IOException;

import java.io.RandomAccessFile;

import java.lang.ref.Reference;

import java.lang.ref.SoftReference;

import java.util.ArrayList;

import java.util.Arrays;

import java.util.Calendar;

import java.util.Collections;

import java.util.LinkedHashMap;

import java.util.HashMap;

import java.util.List;

import java.util.Map;

import java.util.Set;

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 the building of index of a zip archive and access to

 * its context. It also uses a prebuilt index if available.

 * It supports invocations where it will serialize an optimized zip index file

 * to disk.

 *

 * In order to use a secondary index file, set "usezipindex" 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 "{@code -XDcachezipindexdir=<directory>}". If this flag is not

 * provided, the default location is the value of the "java.io.tmpdir" system

 * property.

 *

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

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

 * location specified by the "cachezipindexdir" option.

 *

 * If system property nonBatchMode option is specified 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 supported API.

 * 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 final 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

    final File zipFile;

    private Reference<File> absFileRef;

    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 final int symbolFilePrefixLength;

    private boolean hasPopulatedData = false;

    long lastReferenceTimeStamp = NOT_MODIFIED;

    private final boolean usePreindexedCache;

    private final String preindexedCacheLocation;

    private boolean writeIndex = false;

    public synchronized boolean isOpen() {

        return (zipRandomFile != null);

    }

    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();

    }

    @Override

    public String toString() {

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

    }

    // Just in case...

    @Override

    protected void finalize() throws Throwable {

        closeFile();

        super.finalize();

    }

    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 synchronized void close() {

        writeIndex();

        closeFile();

    }

    private void closeFile() {

        if (zipRandomFile != null) {

            try {

                zipRandomFile.close();

            } catch (IOException ex) {

            }

            zipRandomFile = null;

        }

    }

    /**

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

     */

    synchronized Entry getZipIndexEntry(RelativePath path) {

        try {

            checkIndex();

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

            String lookFor = path.basename();

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

        }

        catch (IOException e) {

            return null;

        }

    }

    /**

     * Returns a javac List of filenames within a directory in the ZipFileIndex.

     */

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

        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();

        }

    }

    public synchronized List<String> getDirectories(RelativeDirectory path) {

        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();

        }

    }

    public synchronized Set<RelativeDirectory> getAllDirectories() {

        try {

            checkIndex();

            if (allDirs == Collections.EMPTY_SET) {

            }

            return allDirs;

        }

        catch (IOException e) {

            return Collections.<RelativeDirectory>emptySet();

        }

    }

    /**

     * 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 synchronized boolean contains(RelativePath path) {

        try {

            checkIndex();

            return getZipIndexEntry(path) != null;

        }

        catch (IOException e) {

            return false;

        }

    }

    public synchronized boolean isDirectory(RelativePath path) throws IOException {

        // 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;

    }

    public synchronized long getLastModified(RelativeFile path) throws IOException {

        Entry entry = getZipIndexEntry(path);

        if (entry == null)

            throw new FileNotFoundException();

        return entry.getLastModified();

    }

    public synchronized int length(RelativeFile path) throws IOException {

        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;

        }

    }

    public synchronized byte[] read(RelativeFile path) throws IOException {

        Entry entry = getZipIndexEntry(path);

        if (entry == null)

            throw new FileNotFoundException("Path not found in ZIP: " + path.path);

        return read(entry);

    }

    synchronized byte[] read(Entry entry) throws IOException {

        openFile();

        byte[] result = readBytes(entry);

        closeFile();

        return result;

    }

    public synchronized int read(RelativeFile path, byte[] buffer) throws IOException {

        Entry entry = getZipIndexEntry(path);

        if (entry == null)

            throw new FileNotFoundException();

        return read(entry, buffer);

    }

    synchronized int read(Entry entry, byte[] buffer)

            throws IOException {

        int result = readBytes(entry, buffer);

        return  result;

    }

    private byte[] readBytes(Entry entry) throws IOException {

        byte[] header = getHeader(entry);

        int csize = entry.compressedSize;

        byte[] cbuf = new byte[csize];

        zipRandomFile.skipBytes(get2ByteLittleEndian(header, 26) + get2ByteLittleEndian(header, 28));

        zipRandomFile.readFully(cbuf, 0, csize);

        // is this compressed - offset 8 in the ZipEntry header

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

            return cbuf;

        int size = entry.size;

        byte[] buf = new byte[size];

        if (inflate(cbuf, buf) != size)

            throw new ZipException("corrupted zip file");

        return buf;

    }

    /**

     *

     */

    private int readBytes(Entry entry, byte[] buffer) throws IOException {

        byte[] header = getHeader(entry);

        // entry is not compressed?

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

            zipRandomFile.skipBytes(get2ByteLittleEndian(header, 26) + get2ByteLittleEndian(header, 28));

            int offset = 0;

            int size = buffer.length;

            while (offset < size) {

                int count = zipRandomFile.read(buffer, offset, size - offset);

                if (count == -1)

                    break;

                offset += count;

            }

            return entry.size;

        }

        int csize = entry.compressedSize;

        byte[] cbuf = new byte[csize];

        zipRandomFile.skipBytes(get2ByteLittleEndian(header, 26) + get2ByteLittleEndian(header, 28));

        zipRandomFile.readFully(cbuf, 0, csize);

        int count = inflate(cbuf, buffer);

        if (count == -1)

            throw new ZipException("corrupted zip file");

        return entry.size;

    }

    //----------------------------------------------------------------------------

    // Zip utilities

    //----------------------------------------------------------------------------

    private byte[] getHeader(Entry entry) throws IOException {

        zipRandomFile.seek(entry.offset);

        byte[] header = new byte[30];

        zipRandomFile.readFully(header);

        if (get4ByteLittleEndian(header, 0) != 0x04034b50)

            throw new ZipException("corrupted zip file");

        if ((get2ByteLittleEndian(header, 6) & 1) != 0)

            throw new ZipException("encrypted zip file"); // offset 6 in the header of the ZipFileEntry

        return header;

    }

  /*

   * Inflate using the java.util.zip.Inflater class

   */

    private SoftReference<Inflater> inflaterRef;

    private int inflate(byte[] src, byte[] dest) {

        Inflater inflater = (inflaterRef == null ? null : inflaterRef.get());

        // construct the inflater object or reuse an existing one

        if (inflater == null)

        inflater.reset();

        inflater.setInput(src);

        try {

            return inflater.inflate(dest);

        } catch (DataFormatException ex) {

            return -1;

        }

    }

    /**

     * return the two bytes buf[pos], buf[pos+1] as an unsigned integer in little

     * endian format.

     */

    private static int get2ByteLittleEndian(byte[] buf, int pos) {

        return (buf[pos] & 0xFF) + ((buf[pos+1] & 0xFF) << 8);

    }

    /**

     * return the 4 bytes buf[i..i+3] as an integer in little endian format.

     */

    private static int get4ByteLittleEndian(byte[] buf, int pos) {

        return (buf[pos] & 0xFF) + ((buf[pos + 1] & 0xFF) << 8) +

                ((buf[pos + 2] & 0xFF) << 16) + ((buf[pos + 3] & 0xFF) << 24);

    }

    /* ----------------------------------------------------------------------------

     * ZipDirectory

     * ----------------------------------------------------------------------------*/

    private class ZipDirectory {

        private RelativeDirectory lastDir;

        private int lastStart;

        private int lastLen;

        byte[] zipDir;

        RandomAccessFile zipRandomFile = null;

        ZipFileIndex zipFileIndex = null;

        public ZipDirectory(RandomAccessFile zipRandomFile, long start, long end, ZipFileIndex index) throws IOException {

            this.zipRandomFile = zipRandomFile;

            this.zipFileIndex = index;

            hasValidHeader();

            findCENRecord(start, end);

        }

        /*

         * the zip entry signature should be at offset 0, otherwise allow the

         * calling logic to take evasive action by throwing ZipFormatException.

         */

        private boolean hasValidHeader() throws IOException {

            final long pos = zipRandomFile.getFilePointer();

            try {

                if (zipRandomFile.read() == 'P') {

                    if (zipRandomFile.read() == 'K') {