/**

  *  @author : Paul Taylor

  *  @author : Eric Farng

  *

  *  Version @version:$Id: NumberFixedLength.java,v 1.12 2008/07/21 10:45:41 paultaylor Exp $

  *

  *  MusicTag Copyright (C)2003,2004

  *

  *  This library is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser

  *  General Public  License as published by the Free Software Foundation; either version 2.1 of the License,

  *  or (at your option) any later version.

  *

  *  This library 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.

  *

  *  You should have received a copy of the GNU Lesser General Public License along with this library; if not,

  *  you can get a copy from http://www.opensource.org/licenses/lgpl-license.php or write to the Free Software

  *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA

  *

  * Description:

  *  Represents a Number of a fixed number of decimal places.

  */

 package org.jaudiotagger.tag.datatype;

 import org.jaudiotagger.tag.InvalidDataTypeException;

 import org.jaudiotagger.tag.id3.AbstractTagFrameBody;

 import org.jaudiotagger.tag.id3.ID3Tags;

 /**

  * Represents a number held as a fixed number of digits.

  * <p/>

  * The bitorder in ID3v2 is most significant bit first (MSB). The byteorder in multibyte numbers is most significant

  * byte first (e.g. $12345678 would be encoded $12 34 56 78), also known as big endian and network byte order.

  * <p/>

  * In ID3Specification would be denoted as $xx xx this denotes exactly two bytes required

  */

 public class NumberFixedLength extends AbstractDataType

 {

     /**

      * Creates a new ObjectNumberFixedLength datatype.

      *

      * @param identifier

      * @param size       the number of significant places that the number is held to

      * @throws IllegalArgumentException

      */

     public NumberFixedLength(String identifier, AbstractTagFrameBody frameBody, int size)

     {

         super(identifier, frameBody);

         if (size < 0)

         {

             throw new IllegalArgumentException("Length is less than zero: " + size);

         }

         this.size = size;

     }

     public NumberFixedLength(NumberFixedLength copy)

     {

         super(copy);

         this.size = copy.size;

     }

     /**

      * Set Size in Bytes of this Object

      *

      * @param size in bytes that this number will be held as

      */

     public void setSize(int size)

     {

         if (size > 0)

         {

             this.size = size;

         }

     }

     /**

      * Return size

      *

      * @return the size of this number

      */

     public int getSize()

     {

         return size;

     }

     public void setValue(Object value)

     {

         if (!(value instanceof Number))

         {

             throw new IllegalArgumentException("Invalid value type for NumberFixedLength:" + value.getClass());

         }

         super.setValue(value);

     }

     /**

      * @param obj

      * @return true if obj equivalent to this

      */

     public boolean equals(Object obj)

     {

         if ((obj instanceof NumberFixedLength) == false)

         {

             return false;

         }

         NumberFixedLength object = (NumberFixedLength) obj;

         if (this.size != object.size)

         {

             return false;

         }

         return super.equals(obj);

     }

     /**

      * Read the number from the byte array

      *

      * @param arr

      * @param offset

      * @throws NullPointerException

      * @throws IndexOutOfBoundsException

      */

     public void readByteArray(byte[] arr, int offset) throws InvalidDataTypeException

     {

         if (arr == null)

         {

             throw new NullPointerException("Byte array is null");

         }

         if ((offset < 0) || (offset >= arr.length))

         {

             throw new InvalidDataTypeException("Offset to byte array is out of bounds: offset = " + offset + ", array.length = " + arr.length);

         }

         long lvalue = 0;

         for (int i = offset; i < (offset + size); i++)

         {

             lvalue <<= 8;

             lvalue += (arr[i] & 0xff);

         }

         value = lvalue;

         logger.info("Read NumberFixedlength:" + value);

     }

     /**

      * @return String representation of this datatype

      */

     public String toString()

     {

         if (value == null)

         {

             return "";

         }

         else

         {

             return value.toString();

         }

     }

     /**

      * Write data to byte array

      *

      * @return the datatype converted to a byte array

      */

     public byte[] writeByteArray()

     {

         byte[] arr;

         arr = new byte[size];

         if (value != null)

         {

             //Convert value to long

             long temp = ID3Tags.getWholeNumber(value);

             for (int i = size - 1; i >= 0; i--)

             {

                 arr[i] = (byte) (temp & 0xFF);

                 temp >>= 8;

             }

         }

         return arr;

     }

 }