package aQute.lib.hex;

import java.io.*;


/*
 * Hex converter.
 * 
 * TODO Implement string to byte[]
 */
public class Hex {
	byte[]				data;
	final static char[] HEX = {'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F'};
	public final static byte[] toByteArray(String string) {
		string = string.trim();
		if ( (string.length() & 1) != 0)
			throw new IllegalArgumentException("a hex string must have an even length");

		byte[]out = new byte[ string.length()/2];
		for ( int i=0; i < out.length; i++) {
			out[i] = (byte) (nibble(string.charAt(i*2))<<4 + nibble(string.charAt(i*2+1)));
		}
		return out;
	}

	
	public final static int nibble( char c) {
		if (c >= '0' && c <= '9')
			return c - '0';
		
		if ( c>='A' && c<='F')
			return c - 'A' + 10;
		if ( c>='a' && c<='f')
			return c - 'a' + 10;
		
		throw new IllegalArgumentException("Not a hex digit: " + c);
	}
	
	public final static String toHexString(byte data[]) {
		StringBuilder sb = new StringBuilder();
		try {
			append(sb,data);
		} catch (IOException e) {
			// cannot happen with sb
		}
		return sb.toString();
	}
	
	public final static void append( Appendable sb, byte [] data ) throws IOException {
		for ( int i =0; i<data.length; i++) {
			sb.append( nibble( data[i] >> 4));
			sb.append( nibble( data[i]));
		}
	}

	private final static char nibble(int i) {	
		return HEX[i & 0xF];
	}
}