/**
 * @author Tomasz Lubinski
 * (c)2007 algorytm.org
 *
 *  UPCA Bar Code
 */
public class BarCode {

	private static final byte right[][] = {
	        {1, 1, 1, 0, 0, 1, 0},
	        {1, 1, 0, 0, 1, 1, 0},
	        {1, 1, 0, 1, 1, 0, 0},
	        {1, 0, 0, 0, 0, 1, 0},
	        {1, 0, 1, 1, 1, 0, 0},
	        {1, 0, 0, 1, 1, 1, 0},
	        {1, 0, 1, 0, 0, 0, 0},
	        {1, 0, 0, 0, 1, 0, 0},
	        {1, 0, 0, 1, 0, 0, 0},
	        {1, 1, 1, 0, 1, 0, 0}
	        };

	private static final byte left[][] = {
            {0, 0, 0, 1, 1, 0, 1},
            {0, 0, 1, 1, 0, 0, 1},
            {0, 0, 1, 0, 0, 1, 1},
            {0, 1, 1, 1, 1, 0, 1},
            {0, 1, 0, 0, 0, 1, 1},
            {0, 1, 1, 0, 0, 0, 1},
            {0, 1, 0, 1, 1, 1, 1},
            {0, 1, 1, 1, 0, 1, 1},
            {0, 1, 1, 0, 1, 1, 1},
            {0, 0, 0, 1, 0, 1, 1}
	        };
	
	public byte[] convert(byte UPCA[]) {
		
		/* inccorect length or check sum, return null */
		if ((UPCA == null) ||
			(UPCA.length != 12) || 
			(checkSum(UPCA) == false)) {
			return null;
		}
		
		byte bars[] = new byte[95];
        for (int i=0; i<95; i++) {
            bars[i] = 0;
        }
        

        bars[0] = 1;
        bars[1] = 0;
        bars[2] = 1;

        for (int i=0; i<6; i++) {
                for (int j=0; j<7; j++) {
                        bars[i*7 + 3 + j] = left[UPCA[i]][j];
                }
        }

        bars[45] = 0;
        bars[46] = 1;
        bars[47] = 0;
        bars[48] = 1;
        bars[49] = 0;

         for (int i=6; i<12; i++) {
                for (int j=0; j<7; j++) {
                        bars[i*7 + 8 + j] = right[UPCA[i]][j];
                }
        }

        bars[92] = 1;
        bars[93] = 0;
        bars[94] = 1;        
        
		return bars;
	}
	
	/**
	 * calculates checksum of UPCA
	 */
	private boolean checkSum(byte UPCA[]) {
		int sum = 3 * UPCA[0] +
				  1 * UPCA[1] +
				  3 * UPCA[2] +
				  1 * UPCA[3] +
				  3 * UPCA[4] +
				  1 * UPCA[5] +
				  3 * UPCA[6] +
				  1 * UPCA[7] +
				  3 * UPCA[8] +
				  1 * UPCA[9] +
				  3 * UPCA[10];
        sum %= 10;
        sum = 10 - sum;
        sum %= 10;
        
		if (sum == UPCA[11]) {
			return true;
		}
		else {
			return false;
		}
	}
}