/*
 * 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} that gets its
 * input from a {@code File} or {@code RandomAccessFile}.
 * 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} that will read
     * from a given {@code File}.
     *
     * <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} to read from.
     *
     * @exception IllegalArgumentException if {@code f} is
     * {@code null}.
     * @exception SecurityException if a security manager exists
     * and does not allow read access to the file.
     * @exception FileNotFoundException if {@code f} 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} that will read
     * from a given {@code RandomAccessFile}.
     *
     * <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} to read from.
     *
     * @exception IllegalArgumentException if {@code raf} is
     * {@code null}.
     */
    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}
     * if it is unknown.
     *
     * @return the file length as a {@code long}, or
     * {@code -1}.
     */
    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
    }
}