/*

 * 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

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

 *

 * 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.

 *

 */

package javax.imageio.stream;

import java.io.File;

import java.io.IOException;

import java.io.OutputStream;

import java.io.RandomAccessFile;

import com.sun.imageio.stream.StreamCloser;

/**

 * An implementation of <code>ImageOutputStream</code> that writes its

 * output to a regular <code>OutputStream</code>.  A file is used to

 * cache data until it is flushed to the output stream.

 *

 */

public class FileCacheImageOutputStream extends ImageOutputStreamImpl {

    private OutputStream stream;

    private File cacheFile;

    private RandomAccessFile cache;

    // Pos after last (rightmost) byte written

    private long maxStreamPos = 0L;

    /** The CloseAction that closes the stream in

     *  the StreamCloser's shutdown hook                     */

    private final StreamCloser.CloseAction closeAction;

    /**

     * Constructs a <code>FileCacheImageOutputStream</code> that will write

     * to a given <code>outputStream</code>.

     *

     * <p> A temporary file is used as a cache.  If

     * <code>cacheDir</code>is non-<code>null</code> and is a

     * directory, the file will be created there.  If it is

     * <code>null</code>, the system-dependent default temporary-file

     * directory will be used (see the documentation for

     * <code>File.createTempFile</code> for details).

     *

     * @param stream an <code>OutputStream</code> to write to.

     * @param cacheDir a <code>File</code> indicating where the

     * cache file should be created, or <code>null</code> to use the

     * system directory.

     *

     * @exception IllegalArgumentException if <code>stream</code>

     * is <code>null</code>.

     * @exception IllegalArgumentException if <code>cacheDir</code> is

     * non-<code>null</code> but is not a directory.

     * @exception IOException if a cache file cannot be created.

     */

    public FileCacheImageOutputStream(OutputStream stream, File cacheDir)

        throws IOException {

        if (stream == null) {

            throw new IllegalArgumentException("stream == null!");

        }

        if ((cacheDir != null) && !(cacheDir.isDirectory())) {

            throw new IllegalArgumentException("Not a directory!");

        }

        this.stream = stream;

        this.cacheFile =

            File.createTempFile("imageio", ".tmp", cacheDir);

        this.cache = new RandomAccessFile(cacheFile, "rw");

        this.closeAction = StreamCloser.createCloseAction(this);

        StreamCloser.addToQueue(closeAction);

    }

    public int read() throws IOException {

        checkClosed();

        bitOffset = 0;

        int val =  cache.read();

        if (val != -1) {

            ++streamPos;

        }

        return val;

    }

    public int read(byte[] b, int off, int len) throws IOException {

        checkClosed();

        if (b == null) {

            throw new NullPointerException("b == null!");

        }

        if (off < 0 || len < 0 || off + len > b.length || off + len < 0) {

            throw new IndexOutOfBoundsException

                ("off < 0 || len < 0 || off+len > b.length || off+len < 0!");

        }

        bitOffset = 0;

        if (len == 0) {

            return 0;

        }

        int nbytes = cache.read(b, off, len);

        if (nbytes != -1) {

            streamPos += nbytes;

        }

        return nbytes;

    }

    public void write(int b) throws IOException {

        flushBits(); // this will call checkClosed() for us

        cache.write(b);

        ++streamPos;

        maxStreamPos = Math.max(maxStreamPos, streamPos);

    }

    public void write(byte[] b, int off, int len) throws IOException {

        flushBits(); // this will call checkClosed() for us

        cache.write(b, off, len);

        streamPos += len;

        maxStreamPos = Math.max(maxStreamPos, streamPos);

    }

    public long length() {

        try {

            checkClosed();

            return cache.length();

        } catch (IOException e) {

            return -1L;

        }

    }

    /**

     * Sets the current stream position and resets the bit offset to

     * 0.  It is legal to seek past the end of the file; an

     * <code>EOFException</code> will be thrown only if a read is

     * performed.  The file length will not be increased until a write

     * is performed.

     *

     * @exception IndexOutOfBoundsException if <code>pos</code> is smaller

     * than the flushed position.

     * @exception IOException if any other I/O error occurs.

     */

    public void seek(long pos) throws IOException {

        checkClosed();

        if (pos < flushedPos) {

            throw new IndexOutOfBoundsException();

        }

        cache.seek(pos);

        this.streamPos = cache.getFilePointer();

        maxStreamPos = Math.max(maxStreamPos, streamPos);

        this.bitOffset = 0;

    }

    /**

     * Returns <code>true</code> since this

     * <code>ImageOutputStream</code> caches data in order to allow

     * seeking backwards.

     *

     * @return <code>true</code>.

     *

     * @see #isCachedMemory

     * @see #isCachedFile

     */

    public boolean isCached() {

        return true;

    }

    /**

     * Returns <code>true</code> since this

     * <code>ImageOutputStream</code> maintains a file cache.

     *

     * @return <code>true</code>.

     *

     * @see #isCached

     * @see #isCachedMemory

     */

    public boolean isCachedFile() {

        return true;

    }

    /**

     * Returns <code>false</code> since this

     * <code>ImageOutputStream</code> does not maintain a main memory

     * cache.

     *

     * @return <code>false</code>.

     *

     * @see #isCached

     * @see #isCachedFile

     */

    public boolean isCachedMemory() {

        return false;

    }

    /**

     * Closes this <code>FileCacheImageOututStream</code>.  All

     * pending data is flushed to the output, and the cache file

     * is closed and removed.  The destination <code>OutputStream</code>

     * is not closed.

     *

     * @exception IOException if an error occurs.

     */

    public void close() throws IOException {

        maxStreamPos = cache.length();

        seek(maxStreamPos);

        flushBefore(maxStreamPos);

        super.close();

        cache.close();

        cache = null;

        cacheFile.delete();

        cacheFile = null;

        stream.flush();

        stream = null;

        StreamCloser.removeFromQueue(closeAction);

    }

    public void flushBefore(long pos) throws IOException {

        long oFlushedPos = flushedPos;

        super.flushBefore(pos); // this will call checkClosed() for us

        long flushBytes = flushedPos - oFlushedPos;

        if (flushBytes > 0) {

            int bufLen = 512;

            byte[] buf = new byte[bufLen];

            cache.seek(oFlushedPos);

            while (flushBytes > 0) {

                int len = (int)Math.min(flushBytes, bufLen);

                cache.readFully(buf, 0, len);

                stream.write(buf, 0, len);

                flushBytes -= len;

            }

            stream.flush();

        }

    }

}