/**
 * @author Tomasz Lubinski
 * (c)2007 algorytm.org
 *
 *  MSI Bar Code
 */
public class BarCode {
	
	  private static final char mod10values[] = {0, 1, 4, 3, 8, 5, 3, 7, 7, 9, 2, 11, 6, 13, 10, 15};
	
	  private static final char MSIsigns[] = {
		  '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F'};

	  private static final char code11bars[][] = {
	        {1, 0, 0, 1, 0, 0, 1, 0, 0, 1, 0, 0},
	        {1, 0, 0, 1, 0, 0, 1, 0, 0, 1, 1, 0},
	        {1, 0, 0, 1, 0, 0, 1, 1, 0, 1, 0, 0},
	        {1, 0, 0, 1, 0, 0, 1, 1, 0, 1, 1, 0},
	        {1, 0, 0, 1, 1, 0, 1, 0, 0, 1, 0, 0},
	        {1, 0, 0, 1, 1, 0, 1, 0, 0, 1, 1, 0},
	        {1, 0, 0, 1, 1, 0, 1, 1, 0, 1, 0, 0},
	        {1, 0, 0, 1, 1, 0, 1, 1, 0, 1, 1, 0},
	        {1, 1, 0, 1, 0, 0, 1, 0, 0, 1, 0, 0},
	        {1, 1, 0, 1, 0, 0, 1, 0, 0, 1, 1, 0},
	        {1, 1, 0, 1, 0, 0, 1, 1, 0, 1, 0, 0},
	        {1, 1, 0, 1, 0, 0, 1, 1, 0, 1, 1, 0},
	        {1, 1, 0, 1, 1, 0, 1, 0, 0, 1, 0, 0},
	        {1, 1, 0, 1, 1, 0, 1, 0, 0, 1, 1, 0},
	        {1, 1, 0, 1, 1, 0, 1, 1, 0, 1, 0, 0},
	        {1, 1, 0, 1, 1, 0, 1, 1, 0, 1, 1, 0}
	  };

	  private static final char start[] = {
		  1, 1, 0
	  };
	  
	  private static final char stop[] = {
		  1, 0, 0, 1
	  };
	  

	  public boolean check(String txt) {
	      for (int i=0; i<txt.length(); i++) {
              if (checkLetter(txt.charAt(i)) == false)
              		return false;
          }
		  return true;
	  }

	  private boolean checkLetter(char ch) {
	        for (int i=0; i<MSIsigns.length; i++) {
                if (MSIsigns[i] == ch)
                	return true;
	        }
	        return false;
	  }
	  
	  public char[] getBars(char ch) {
	        for (int i=0; i<MSIsigns.length; i++) {
                if (MSIsigns[i] == ch)
                	return code11bars[i];
	        }		  
		  return null;
	  }
	  
	  public char[] getStartBars() {
		  return start;
	  }
	  
	  public char[] getStopBars() {
		  return stop;
	  }
	  
	    
	  //returns letter value for check digit
	  private int getLetterValue(char ch) {
	          for (int i=0; i<MSIsigns.length; i++)
	                  if (MSIsigns[i] == ch)
	                          return i;

	          return 0;
	  }
	  
	  public boolean checkCheckDigit(String txt, int checkDigitType) {
		    int len = txt.length();
		    
	        // check check digits
		    switch (checkDigitType) {
		    		case 1:
	                if (getLetterValue(txt.charAt(len-1)) != mod10checkDigit(txt, len-1))
	                {
	                        return false;
	                }
	                break;
	                
		    		case 2:
	                if (getLetterValue(txt.charAt(len-2)) != mod10checkDigit(txt, len-2) ||
	                    getLetterValue(txt.charAt(len-1)) != mod10checkDigit(txt, len-1))
	                {
	                        return false;
	                }
	                break;
	                
		    		case 3:
	                if (getLetterValue(txt.charAt(len-1)) != mod11checkDigit(txt, len-1))
	                {
	                        return false;
	                }
	                break;
	                
		    		case 4:
	                if (getLetterValue(txt.charAt(len-2)) != mod11checkDigit(txt, len-2) ||
	                    getLetterValue(txt.charAt(len-1)) != mod10checkDigit(txt, len-1))
	                {
	                        return false;
	                }
	                break;
	        }

	        return true;		  
	  }
	  
	  //calculate modulo 10 check digit
	  private int mod10checkDigit (String code, int length)
	  {
	          int sum = 0;
	          for (int i=0; i<length; i++)
	          {
	                  sum += mod10values[getLetterValue(code.charAt(i))];
	          }
	          sum %= 10;
	          sum = 10-sum;
	          sum %= 10;

	          return sum;
	  }

	  //calculate modulo 11 check digit
	  private int mod11checkDigit (String code, int length)
	  {
	          int sum = 0;
	          int w = 0;

	          for (int i=length-1; i>=0; i--)
	          {
	                  sum += getLetterValue(code.charAt(i)) * (w + 2);
	                  w++;
	                  w %= 6;
	          }
	          sum %= 11;
	          sum = 11-sum;
	          sum %= 11;

	          return sum;
	  }	  
}