/*
 * Entagged Audio Tag library
 * Copyright (c) 2003-2005 Rapha�l Slinckx <raphael@slinckx.net>
 * 
 * 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, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 */
package entagged.audioformats.generic;

import java.io.File;
import java.io.UnsupportedEncodingException;

/**
 * Contains various frequently used static functions in the different tag
 * formats
 * 
 * @author Raphael Slinckx
 */
public class Utils {

	/**
	 * Copies the bytes of <code>srd</code> to <code>dst</code> at the
	 * specified offset.
	 * 
	 * @param src
	 *            The byte do be copied.
	 * @param dst
	 *            The array to copy to
	 * @param dstOffset
	 *            The start offset for the bytes to be copied.
	 */
	public static void copy(byte[] src, byte[] dst, int dstOffset) {
		System.arraycopy(src, 0, dst, dstOffset, src.length);
	}

	/**
	 * Returns {@link String#getBytes()}.<br>
	 * 
	 * @param s
	 *            The String to call.
	 * @return The bytes.
	 */
	public static byte[] getDefaultBytes(String s) {
		return s.getBytes();
	}
	/*
	 * Returns the extension of the given file.
	 * The extension is empty if there is no extension
	 * The extension is the string after the last "."
	 * 
	 * @param f The file whose extension is requested
	 * @return The extension of the given file
	 */
	public static String getExtension(File f) {
		String name = f.getName().toLowerCase();
		int i = name.lastIndexOf( "." );
		if(i == -1)
			return "";
		
		return name.substring( i + 1 );
	}

	/*
	 * Returns the extension of the given file. The extension is empty if there
	 * is no extension The extension is the string after the last "."
	 * 
	 * @param f The file whose extension is requested @return The extension of
	 * the given file&&
	 * 
	 * public static String getExtension(File f) { String name =
	 * f.getName().toLowerCase(); int i = name.lastIndexOf("."); if (i == -1)
	 * return "";
	 * 
	 * return name.substring(i + 1); }
	 *  /* Computes a number composed of (end-start) bytes in the b array.
	 * 
	 * @param b The byte array @param start The starting offset in b
	 * (b[offset]). The less significant byte @param end The end index
	 * (included) in b (b[end]). The most significant byte @return a long number
	 * represented by the byte sequence.
	 */
	public static long getLongNumber(byte[] b, int start, int end) {
		long number = 0;
		for (int i = 0; i < (end - start + 1); i++) {
			number += ((b[start + i] & 0xFF) << i * 8);
		}

		return number;
	}

	public static long getLongNumberBigEndian(byte[] b, int start, int end) {
		int number = 0;
		for (int i = 0; i < (end - start + 1); i++) {
			number += ((b[end - i] & 0xFF) << i * 8);
		}

		return number;
	}

	/*
	 * same as above, but returns an int instead of a long @param b The byte
	 * array @param start The starting offset in b (b[offset]). The less
	 * significant byte @param end The end index (included) in b (b[end]). The
	 * most significant byte @return a int number represented by the byte
	 * sequence.
	 */
	public static int getNumber(byte[] b, int start, int end) {
		return (int) getLongNumber(b, start, end);
	}

	public static int getNumberBigEndian(byte[] b, int start, int end) {
		return (int) getLongNumberBigEndian(b, start, end);
	}

	public static byte[] getSizeBigEndian(int size) {
		byte[] b = new byte[4];
		b[0] = (byte) ((size >> 24) & 0xFF);
		b[1] = (byte) ((size >> 16) & 0xFF);
		b[2] = (byte) ((size >> 8) & 0xFF);
		b[3] = (byte) (size & 0xFF);
		return b;
	}

	public static String getString(byte[] b, int offset, int length) {
		return new String(b, offset, length);
	}

	public static String getString(byte[] b, int offset, int length,
			String encoding) throws UnsupportedEncodingException {
		return new String(b, offset, length, encoding);
	}

	/*
	 * Tries to convert a string into an UTF8 array of bytes If the conversion
	 * fails, return the string converted with the default encoding.
	 * 
	 * @param s The string to convert @return The byte array representation of
	 * this string in UTF8 encoding
	 */
	public static byte[] getUTF8Bytes(String s)
			throws UnsupportedEncodingException {
		return s.getBytes("UTF-8");
	}
}