/*

 * Copyright (c) 2000, 2007, 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 javax.imageio.stream;

import java.io.File;

import java.io.FileNotFoundException;

import java.io.IOException;

import java.io.RandomAccessFile;

import com.sun.imageio.stream.CloseableDisposerRecord;

import com.sun.imageio.stream.StreamFinalizer;

import sun.java2d.Disposer;

/**

 * An implementation of <code>ImageInputStream</code> that gets its

 * input from a <code>File</code> or <code>RandomAccessFile</code>.

 * The file contents are assumed to be stable during the lifetime of

 * the object.

 *

 */

public class FileImageInputStream extends ImageInputStreamImpl {

    private RandomAccessFile raf;

    /** The referent to be registered with the Disposer. */

    private final Object disposerReferent;

    /** The DisposerRecord that closes the underlying RandomAccessFile. */

    private final CloseableDisposerRecord disposerRecord;

    /**

     * Constructs a <code>FileImageInputStream</code> that will read

     * from a given <code>File</code>.

     *

     * <p> The file contents must not change between the time this

     * object is constructed and the time of the last call to a read

     * method.

     *

     * @param f a <code>File</code> to read from.

     *

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

     * <code>null</code>.

     * @exception SecurityException if a security manager exists

     * and does not allow read access to the file.

     * @exception FileNotFoundException if <code>f</code> is a

     * directory or cannot be opened for reading for any other reason.

     * @exception IOException if an I/O error occurs.

     */

    public FileImageInputStream(File f)

        throws FileNotFoundException, IOException {

        this(f == null ? null : new RandomAccessFile(f, "r"));

    }

    /**

     * Constructs a <code>FileImageInputStream</code> that will read

     * from a given <code>RandomAccessFile</code>.

     *

     * <p> The file contents must not change between the time this

     * object is constructed and the time of the last call to a read

     * method.

     *

     * @param raf a <code>RandomAccessFile</code> to read from.

     *

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

     * <code>null</code>.

     */

    public FileImageInputStream(RandomAccessFile raf) {

        if (raf == null) {

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

        }

        this.raf = raf;

        disposerRecord = new CloseableDisposerRecord(raf);

        if (getClass() == FileImageInputStream.class) {

            disposerReferent = new Object();

            Disposer.addRecord(disposerReferent, disposerRecord);

        } else {

            disposerReferent = new StreamFinalizer(this);

        }

    }

    public int read() throws IOException {

        checkClosed();

        bitOffset = 0;

        int val = raf.read();

        if (val != -1) {

            ++streamPos;

        }

        return val;

    }

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

        checkClosed();

        bitOffset = 0;

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

        if (nbytes != -1) {

            streamPos += nbytes;

        }

        return nbytes;

    }

    /**

     * Returns the length of the underlying file, or <code>-1</code>

     * if it is unknown.

     *

     * @return the file length as a <code>long</code>, or

     * <code>-1</code>.

     */

    public long length() {

        try {

            checkClosed();

            return raf.length();

        } catch (IOException e) {

            return -1L;

        }

    }

    public void seek(long pos) throws IOException {

        checkClosed();

        if (pos < flushedPos) {

            throw new IndexOutOfBoundsException("pos < flushedPos!");

        }

        bitOffset = 0;

        raf.seek(pos);

        streamPos = raf.getFilePointer();

    }

    public void close() throws IOException {

        super.close();

        disposerRecord.dispose(); // this closes the RandomAccessFile

        raf = null;

    }

    /**

     * {@inheritDoc}

     */

    protected void finalize() throws Throwable {

        // Empty finalizer: for performance reasons we instead use the

        // Disposer mechanism for ensuring that the underlying

        // RandomAccessFile is closed prior to garbage collection

    }

}