/*
 * This program is free software; you can redistribute it and/or modify it under the
 * terms of the GNU Lesser General Public License, version 2.1 as published by the Free Software
 * Foundation.
 *
 * You should have received a copy of the GNU Lesser General Public License along with this
 * program; if not, you can obtain a copy at http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html
 * or from the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * This program 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 Lesser General Public License for more details.
 *
 * Copyright (c) 2000 - 2009 Pentaho Corporation, Object Refinery Limited and Contributors.  All rights reserved.
 */

package org.pentaho.reporting.libraries.pixie.wmf;

import java.io.ByteArrayInputStream;
import java.io.EOFException;
import java.io.IOException;
import java.io.InputStream;

/**
 * A block of raw mmeory. This is used to store various metafile objects as they are read
 * in from file.
 */
public class Buffer
{
  /**
   * The memory itself.
   */
  private byte[] bytes;

  /**
   * The current length of the memory.
   */
  private int length;

  /**
   * Default Constructor. Defines a buffer without an initial size.
   */
  protected Buffer()
  {
  }

  /**
   * Defines a new buffer with the given initial size in bytes.
   *
   * @param length the length of the buffer in bytes.
   */
  protected Buffer(final int length)
  {
    setCapacity(length);
  }

  /**
   * The size of the stored data in the memory.
   */
  public final int getLength()
  {
    return length;
  }

  /**
   * Extends the length to the given new size.
   *
   * @param len the new length.
   * @throws IllegalArgumentException if the length is shorter than the used storage in
   *                                  memory.
   */
  protected void setLength(final int len)
  {
    if (len > bytes.length)
    {
      throw new IllegalArgumentException();
    }

    this.length = len;
  }

  /**
   * Ensures that the buffer has enough space for the given number of bytes.
   *
   * @param capacity the new capacity that should be ensured.
   * @throws IllegalArgumentException if the capacity is smaller than the buffers length.
   */
  protected void setCapacity(final int capacity)
  {
    if (capacity < getLength())
    {
      throw new IllegalArgumentException();
    }

    if (bytes == null || bytes.length == 0)
    {
      bytes = new byte[capacity];
    }
    else if (capacity != bytes.length)
    {
      final byte[] old = bytes;
      bytes = new byte[capacity];
      System.arraycopy(old, 0, bytes, 0, Math.min(old.length, capacity));
    }
  }

  /**
   * Read <code>len</code> bytes into the memory from a stream and stores the read bytes
   * at the given offset.
   *
   * @param in     the input stream that should be used
   * @param offset the offset
   * @param len    the number bytes that should be read.
   */
  public void read(final InputStream in, int offset, int len)
      throws IOException
  {
    // make sure, that all bytes can be read and create the buffer if needed.
    if (bytes == null || offset + len > bytes.length)
    {
      setCapacity(offset + len);
    }

    //in.readFully( bytes, offset, len );
    while (len > 0)
    {
      final int blockSize = in.read(bytes, offset, len);
      if (blockSize <= 0)
      {
        throw new EOFException();
      }
      offset += blockSize;
      len -= blockSize;
      setLength(offset);
    }
  }

  /**
   * Moves the buffer contents from the source offset to the target offset, the areas
   * should not overlap.
   *
   * @param sourceoffset
   * @param length
   * @param targetoffset
   */
  protected void move(final int sourceoffset, final int length, final int targetoffset)
  {
    System.arraycopy(bytes, sourceoffset, bytes, targetoffset, length);
  }

  /**
   * Set the int value as big-endian.
   *
   * @param offset the offset where to set the int value.
   * @param value  the integer value that should be set.
   */
  public void setInt(final int offset, final int value)
  {
    if (offset > (getLength() - 4))
    {
      throw new IndexOutOfBoundsException();
    }

    setShort(offset, value & 0x0ffff);
    setShort(offset + 2, value >> 16);
  }

  /**
   * Return the 32-bit int at the given byte offset.
   *
   * @param offset the offset where the integer value is stored in the memory
   * @return the integer.
   */
  public int getInt(final int offset)
  {
    if (offset > (getLength() - 4))
    {
      throw new IndexOutOfBoundsException();
    }

    return (getShort(offset) & 0x0ffff) | (getShort(offset + 2) << 16);
  }

  /**
   * Stores the given short as BigEndian value.
   *
   * @param offset   the offset.
   * @param shortval the shortvalue.
   */
  public void setShort(final int offset, final int shortval)
  {
    if (offset > (getLength() - 2))
    {
      throw new IndexOutOfBoundsException();
    }

    bytes[offset] = (byte) (shortval & 0x0ff);
    bytes[offset + 1] = (byte) (shortval >> 8);
  }

  /**
   * Return the 16-bit int at the given byte offset.
   *
   * @param offset the offset from where to read the short.
   * @return the short.
   */
  public int getShort(final int offset)
  {
    if (offset > (getLength() - 2))
    {
      throw new IndexOutOfBoundsException
          ("Offset " + offset + " is out of limit. " +
              "Max length is " + (getLength() - 2));
    }

    return (bytes[offset] & 0x0ff) | (bytes[offset + 1] << 8);
  }

  /**
   * Sets the byte at the given offset.
   *
   * @param offset the offset.
   * @param value  the byte that should be set.
   */
  public void setByte(final int offset, final int value)
  {
    if (offset > (getLength() - 1))
    {
      throw new IndexOutOfBoundsException();
    }

    bytes[offset] = (byte) (value & 0x0ff);
  }

  /**
   * Return the 8-bit int at the given byte offset.
   *
   * @param offset the offset from where to read the byte
   * @return the byte read.
   */
  public int getByte(final int offset)
  {
    if (offset > (getLength() - 1))
    {
      throw new IndexOutOfBoundsException();
    }

    return bytes[offset] & 0x0ff;
  }

  /**
   * Writes the given string as byte stream using the plattforms default encoding.
   *
   * @param offset the offset, where to store the string.
   * @param str    the string that should be stored in the Wmf.
   */
  public void setString(final int offset, final String str)
  {
    if ((offset + str.length()) > (getLength() - 1))
    {
      throw new IndexOutOfBoundsException();
    }

    final byte[] b = str.getBytes();

    final int len = getLength() - offset;

    for (int i = 0; i < len; i++)
    {
      bytes[offset + i] = b[offset];
    }
    if ((offset + len) < getLength())
    {
      bytes[offset + len] = 0;
    }
  }

  /**
   * Return the null-terminated string at the given byte offset with the given maximum
   * length.
   *
   * @param offset the offset where the string starts
   * @param len    the maximum length of the string
   * @return the null-terminated string read.
   */
  public String getString(final int offset, final int len)
  {
    int i;
    for (i = 0; i < len; i++)
    {
      if (bytes[offset + i] == 0)
      {
        break;
      }
    }
    return new String(bytes, offset, i);
  }

  /**
   * Gets an input stream to read from the memory buffer.
   *
   * @param offset the offse, from where to read.
   * @return the InputStream.
   */
  public InputStream getInputStream(final int offset)
  {
    return new ByteArrayInputStream(bytes, offset, bytes.length - offset);
  }
}