/*

 * Copyright 2000-2008 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 javax.imageio.stream;

import java.io.DataInputStream;

import java.io.EOFException;

import java.io.IOException;

import java.nio.ByteOrder;

import java.util.Stack;

import javax.imageio.IIOException;

/**

 * An abstract class implementing the <code>ImageInputStream</code> interface.

 * This class is designed to reduce the number of methods that must

 * be implemented by subclasses.

 *

 * <p> In particular, this class handles most or all of the details of

 * byte order interpretation, buffering, mark/reset, discarding,

 * closing, and disposing.

 */

public abstract class ImageInputStreamImpl implements ImageInputStream {

    private Stack markByteStack = new Stack();

    private Stack markBitStack = new Stack();

    private boolean isClosed = false;

    // Length of the buffer used for readFully(type[], int, int)

    private static final int BYTE_BUF_LENGTH = 8192;

    /**

     * Byte buffer used for readFully(type[], int, int).  Note that this

     * array is also used for bulk reads in readShort(), readInt(), etc, so

     * it should be large enough to hold a primitive value (i.e. >= 8 bytes).

     * Also note that this array is package protected, so that it can be

     * used by ImageOutputStreamImpl in a similar manner.

     */

    byte[] byteBuf = new byte[BYTE_BUF_LENGTH];

    /**

     * The byte order of the stream as an instance of the enumeration

     * class <code>java.nio.ByteOrder</code>, where

     * <code>ByteOrder.BIG_ENDIAN</code> indicates network byte order

     * and <code>ByteOrder.LITTLE_ENDIAN</code> indicates the reverse

     * order.  By default, the value is

     * <code>ByteOrder.BIG_ENDIAN</code>.

     */

    protected ByteOrder byteOrder = ByteOrder.BIG_ENDIAN;

    /**

     * The current read position within the stream.  Subclasses are

     * responsible for keeping this value current from any method they

     * override that alters the read position.

     */

    protected long streamPos;

    /**

     * The current bit offset within the stream.  Subclasses are

     * responsible for keeping this value current from any method they

     * override that alters the bit offset.

     */

    protected int bitOffset;

    /**

     * The position prior to which data may be discarded.  Seeking

     * to a smaller position is not allowed.  <code>flushedPos</code>

     * will always be >= 0.

     */

    protected long flushedPos = 0;

    /**

     * Constructs an <code>ImageInputStreamImpl</code>.

     */

    public ImageInputStreamImpl() {

    }

    /**

     * Throws an <code>IOException</code> if the stream has been closed.

     * Subclasses may call this method from any of their methods that

     * require the stream not to be closed.

     *

     * @exception IOException if the stream is closed.

     */

    protected final void checkClosed() throws IOException {

        if (isClosed) {

            throw new IOException("closed");

        }

    }

    public void setByteOrder(ByteOrder byteOrder) {

        this.byteOrder = byteOrder;

    }

    public ByteOrder getByteOrder() {

        return byteOrder;

    }

    /**

     * Reads a single byte from the stream and returns it as an

     * <code>int</code> between 0 and 255.  If EOF is reached,

     * <code>-1</code> is returned.

     *

     * <p> Subclasses must provide an implementation for this method.

     * The subclass implementation should update the stream position

     * before exiting.

     *

     * <p> The bit offset within the stream must be reset to zero before

     * the read occurs.

     *

     * @return the value of the next byte in the stream, or <code>-1</code>

     * if EOF is reached.

     *

     * @exception IOException if the stream has been closed.

     */

    public abstract int read() throws IOException;

    /**

     * A convenience method that calls <code>read(b, 0, b.length)</code>.

     *

     * <p> The bit offset within the stream is reset to zero before

     * the read occurs.

     *

     * @return the number of bytes actually read, or <code>-1</code>

     * to indicate EOF.

     *

     * @exception NullPointerException if <code>b</code> is

     * <code>null</code>.

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

     */

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

        return read(b, 0, b.length);

    }

    /**

     * Reads up to <code>len</code> bytes from the stream, and stores

     * them into <code>b</code> starting at index <code>off</code>.

     * If no bytes can be read because the end of the stream has been

     * reached, <code>-1</code> is returned.

     *

     * <p> The bit offset within the stream must be reset to zero before

     * the read occurs.

     *

     * <p> Subclasses must provide an implementation for this method.

     * The subclass implementation should update the stream position

     * before exiting.

     *

     * @param b an array of bytes to be written to.

     * @param off the starting position within <code>b</code> to write to.

     * @param len the maximum number of bytes to read.

     *

     * @return the number of bytes actually read, or <code>-1</code>

     * to indicate EOF.

     *

     * @exception IndexOutOfBoundsException if <code>off</code> is

     * negative, <code>len</code> is negative, or <code>off +

     * len</code> is greater than <code>b.length</code>.

     * @exception NullPointerException if <code>b</code> is

     * <code>null</code>.

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

     */

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

    public void readBytes(IIOByteBuffer buf, int len) throws IOException {

        if (len < 0) {

            throw new IndexOutOfBoundsException("len < 0!");

        }

        if (buf == null) {

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

        }

        byte[] data = new byte[len];

        len = read(data, 0, len);

        buf.setData(data);

        buf.setOffset(0);

        buf.setLength(len);

    }

    public boolean readBoolean() throws IOException {

        int ch = this.read();

        if (ch < 0) {

            throw new EOFException();

        }

        return (ch != 0);

    }

    public byte readByte() throws IOException {

        int ch = this.read();

        if (ch < 0) {

            throw new EOFException();

        }

        return (byte)ch;

    }

    public int readUnsignedByte() throws IOException {

        int ch = this.read();

        if (ch < 0) {

            throw new EOFException();

        }

        return ch;

    }

    public short readShort() throws IOException {

        if (read(byteBuf, 0, 2) < 0) {

            throw new EOFException();

        }

        if (byteOrder == ByteOrder.BIG_ENDIAN) {

            return (short)

                (((byteBuf[0] & 0xff) << 8) | ((byteBuf[1] & 0xff) << 0));

        } else {

            return (short)

                (((byteBuf[1] & 0xff) << 8) | ((byteBuf[0] & 0xff) << 0));

        }

    }

    public int readUnsignedShort() throws IOException {

        return ((int)readShort()) & 0xffff;

    }

    public char readChar() throws IOException {

        return (char)readShort();

    }

    public int readInt() throws IOException {

        if (read(byteBuf, 0, 4) < 0) {

            throw new EOFException();

        }

        if (byteOrder == ByteOrder.BIG_ENDIAN) {

            return

                (((byteBuf[0] & 0xff) << 24) | ((byteBuf[1] & 0xff) << 16) |

                 ((byteBuf[2] & 0xff) <<  8) | ((byteBuf[3] & 0xff) <<  0));

        } else {

            return

                (((byteBuf[3] & 0xff) << 24) | ((byteBuf[2] & 0xff) << 16) |

                 ((byteBuf[1] & 0xff) <<  8) | ((byteBuf[0] & 0xff) <<  0));

        }

    }

    public long readUnsignedInt() throws IOException {

        return ((long)readInt()) & 0xffffffffL;

    }

    public long readLong() throws IOException {

        // REMIND: Once 6277756 is fixed, we should do a bulk read of all 8

        // bytes here as we do in readShort() and readInt() for even better

        // performance (see 6347575 for details).

        int i1 = readInt();

        int i2 = readInt();

        if (byteOrder == ByteOrder.BIG_ENDIAN) {

            return ((long)i1 << 32) + (i2 & 0xFFFFFFFFL);

        } else {

            return ((long)i2 << 32) + (i1 & 0xFFFFFFFFL);

        }

    }

    public float readFloat() throws IOException {

        return Float.intBitsToFloat(readInt());

    }

    public double readDouble() throws IOException {

        return Double.longBitsToDouble(readLong());

    }

    public String readLine() throws IOException {

        StringBuffer input = new StringBuffer();

        int c = -1;

        boolean eol = false;

        while (!eol) {

            switch (c = read()) {

            case -1:

            case '\n':

                eol = true;

                break;

            case '\r':

                eol = true;

                long cur = getStreamPosition();

                if ((read()) != '\n') {

                    seek(cur);

                }

                break;

            default:

                input.append((char)c);

                break;

            }

        }

        if ((c == -1) && (input.length() == 0)) {

            return null;

        }

        return input.toString();

    }

    public String readUTF() throws IOException {

        this.bitOffset = 0;

        // Fix 4494369: method ImageInputStreamImpl.readUTF()

        // does not work as specified (it should always assume

        // network byte order).

        ByteOrder oldByteOrder = getByteOrder();

        setByteOrder(ByteOrder.BIG_ENDIAN);

        String ret;

        try {

            ret = DataInputStream.readUTF(this);

        } catch (IOException e) {

            // Restore the old byte order even if an exception occurs

            setByteOrder(oldByteOrder);

            throw e;

        }

        setByteOrder(oldByteOrder);

        return ret;

    }

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

        // Fix 4430357 - if off + len < 0, overflow occurred

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

            throw new IndexOutOfBoundsException

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

        }

        while (len > 0) {

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

            if (nbytes == -1) {

                throw new EOFException();

            }

            off += nbytes;

            len -= nbytes;

        }

    }

    public void readFully(byte[] b) throws IOException {

        readFully(b, 0, b.length);

    }

    public void readFully(short[] s, int off, int len) throws IOException {

        // Fix 4430357 - if off + len < 0, overflow occurred

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

            throw new IndexOutOfBoundsException

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

        }

        while (len > 0) {

            int nelts = Math.min(len, byteBuf.length/2);

            readFully(byteBuf, 0, nelts*2);

            toShorts(byteBuf, s, off, nelts);

            off += nelts;

            len -= nelts;

        }

    }

    public void readFully(char[] c, int off, int len) throws IOException {

        // Fix 4430357 - if off + len < 0, overflow occurred

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

            throw new IndexOutOfBoundsException

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

        }

        while (len > 0) {

            int nelts = Math.min(len, byteBuf.length/2);

            readFully(byteBuf, 0, nelts*2);

            toChars(byteBuf, c, off, nelts);

            off += nelts;

            len -= nelts;

        }

    }

    public void readFully(int[] i, int off, int len) throws IOException {

        // Fix 4430357 - if off + len < 0, overflow occurred

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

            throw new IndexOutOfBoundsException

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

        }

        while (len > 0) {

            int nelts = Math.min(len, byteBuf.length/4);

            readFully(byteBuf, 0, nelts*4);

            toInts(byteBuf, i, off, nelts);

            off += nelts;

            len -= nelts;

        }

    }

    public void readFully(long[] l, int off, int len) throws IOException {

        // Fix 4430357 - if off + len < 0, overflow occurred

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

            throw new IndexOutOfBoundsException

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

        }

        while (len > 0) {

            int nelts = Math.min(len, byteBuf.length/8);

            readFully(byteBuf, 0, nelts*8);

            toLongs(byteBuf, l, off, nelts);

            off += nelts;

            len -= nelts;

        }

    }

    public void readFully(float[] f, int off, int len) throws IOException {

        // Fix 4430357 - if off + len < 0, overflow occurred

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

            throw new IndexOutOfBoundsException

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

        }

        while (len > 0) {

            int nelts = Math.min(len, byteBuf.length/4);

            readFully(byteBuf, 0, nelts*4);

            toFloats(byteBuf, f, off, nelts);

            off += nelts;

            len -= nelts;

        }

    }

    public void readFully(double[] d, int off, int len) throws IOException {

        // Fix 4430357 - if off + len < 0, overflow occurred

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

            throw new IndexOutOfBoundsException

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

        }

        while (len > 0) {

            int nelts = Math.min(len, byteBuf.length/8);

            readFully(byteBuf, 0, nelts*8);

            toDoubles(byteBuf, d, off, nelts);

            off += nelts;

            len -= nelts;

        }

    }

    private void toShorts(byte[] b, short[] s, int off, int len) {

        int boff = 0;

        if (byteOrder == ByteOrder.BIG_ENDIAN) {

            for (int j = 0; j < len; j++) {

                int b0 = b[boff];

                int b1 = b[boff + 1] & 0xff;

                s[off + j] = (short)((b0 << 8) | b1);

                boff += 2;

            }

        } else {

            for (int j = 0; j < len; j++) {

                int b0 = b[boff + 1];

                int b1 = b[boff] & 0xff;

                s[off + j] = (short)((b0 << 8) | b1);

                boff += 2;

            }

        }

    }

    private void toChars(byte[] b, char[] c, int off, int len) {

        int boff = 0;

        if (byteOrder == ByteOrder.BIG_ENDIAN) {

            for (int j = 0; j < len; j++) {

                int b0 = b[boff];

                int b1 = b[boff + 1] & 0xff;

                c[off + j] = (char)((b0 << 8) | b1);

                boff += 2;

            }

        } else {

            for (int j = 0; j < len; j++) {

                int b0 = b[boff + 1];

                int b1 = b[boff] & 0xff;

                c[off + j] = (char)((b0 << 8) | b1);

                boff += 2;

            }

        }

    }

    private void toInts(byte[] b, int[] i, int off, int len) {

        int boff = 0;

        if (byteOrder == ByteOrder.BIG_ENDIAN) {

            for (int j = 0; j < len; j++) {

                int b0 = b[boff];

                int b1 = b[boff + 1] & 0xff;

                int b2 = b[boff + 2] & 0xff;

                int b3 = b[boff + 3] & 0xff;

                i[off + j] = (b0 << 24) | (b1 << 16) | (b2 << 8) | b3;

                boff += 4;

            }

        } else {

            for (int j = 0; j < len; j++) {

                int b0 = b[boff + 3];

                int b1 = b[boff + 2] & 0xff;

                int b2 = b[boff + 1] & 0xff;

                int b3 = b[boff] & 0xff;

                i[off + j] = (b0 << 24) | (b1 << 16) | (b2 << 8) | b3;

                boff += 4;

            }

        }

    }

    private void toLongs(byte[] b, long[] l, int off, int len) {

        int boff = 0;

        if (byteOrder == ByteOrder.BIG_ENDIAN) {

            for (int j = 0; j < len; j++) {

                int b0 = b[boff];

                int b1 = b[boff + 1] & 0xff;

                int b2 = b[boff + 2] & 0xff;

                int b3 = b[boff + 3] & 0xff;