//BC412
//(c) 2019 by Tomasz Lubinski
//www.algorytm.org

   var bc412chars = [
       '0', 'R', '9', 'G', 'L', 'V', 'H', 'A', '8', 'E',
       'Z', '4', 'N', 'T', 'S', '1', 'J', '2', 'Q', '6', 
       'C', '7', 'D', 'Y', 'K', 'B', 'U', 'I', 'X', '3', 
       'F', 'W', 'P', '5', 'M' ];

   var bc412spaces = [
      [1, 1, 1, 5],
      [3, 1, 2, 2],
      [1, 3, 1, 3],
      [2, 1, 2, 3],
      [2, 2, 3, 1],
      [3, 3, 1, 1],
      [2, 1, 3, 2],
      [1, 3, 2, 2],
      [1, 2, 4, 1],
      [1, 5, 1, 1],
      [5, 1, 1, 1],
      [1, 1, 5, 1],
      [2, 3, 2, 1],
      [3, 2, 1, 2],
      [3, 1, 2, 2],
      [1, 1, 2, 4],
      [2, 2, 1, 3],
      [1, 1, 3, 3],
      [3, 1, 1, 3],
      [1, 2, 2, 3],
      [1, 4, 1, 2],
      [1, 2, 3, 2],
      [1, 4, 2, 1],
      [4, 2, 1, 1],
      [2, 2, 2, 2],
      [1, 3, 3, 1],
      [3, 2, 2, 1],
      [2, 1, 4, 1],
      [4, 1, 2, 1],
      [1, 1, 4, 2],
      [2, 1, 1, 4],
      [4, 1, 1, 2],
      [2, 4, 1, 1],
      [1, 2, 1, 4],
      [2, 3, 1, 2]
   ];

   var start = 2;
   var stop = 1;
	  
/* Check if code is correct */
function check(bc412)
{
   for (var i=0; i<bc412.length; i++) 
   {
      if (getLetterIndex(bc412[i]) == -1)
         return false;
   }
   return true;
}

/* Return letter index, or -1 if not correct */
function getLetterIndex(ch) 
{
   for (var i=0; i<bc412chars.length; i++) 
   {
      if (bc412chars[i] == ch)
         return i;
   }
   return -1;
}

function checkDigit(bc412)
{
   var sum = 0;
   for (var i = 0; i < bc412.length; i++)
   {
      sum += getLetterIndex(bc412[i]);
   }
      
   return (sum % 35);
}
	  
/* Convert code to bars */
function convert(bc412) {

   /* inccorect code return null */
   if (check(bc412) == false) 
   {
      return null;
   }

   var bars = new Array(4*(bc412.length+1) + 2);

   /* add start bars */
   bars[0] = start;

   /* add character codes */
   for (var i=0; i<bc412.length; i++) 
   {
      var toCopy = bc412spaces[getLetterIndex(bc412[i])];
      for (var j=0; j<4; j++) 
      {
          bars[i * 4 + 1 + j] = toCopy[j];
      }
   }
   
   /* add check digit*/
   var toCopy = bc412spaces[checkDigit(bc412)];
   for (var j = 0; j < 4; j++)
   {
      bars[4 * bc412.length + 1 + j] = toCopy[j];
   }

   /* add stop bars */
   bars[4 * (bc412.length + 1) + 1] = stop
   
   return bars;
}

//initialize data
function generate(bc412)
{
   var canvas = document.getElementById("canvas");
   var ctx = canvas.getContext("2d");

   /* clear canvas and set its width */
   canvas.width = bc412.length*24+50;

   /* prepare style */
   ctx.fillStyle    = "rgb(0,0,0)";
   ctx.font         = "10pt Arial";
   ctx.textBaseline = "top";
   ctx.textAlign    = "left";

   bc412 = bc412.toUpperCase();
   bc412 = bc412.replace(/O/g, "0")
   var bars = convert(bc412);
   if (bars != null)
   {
      var pos = 10;
      for (i=0; i<bars.length; i++) 
      {
         /* Draw a bar and shift by requested space */
         ctx.fillRect(pos, 10, 2, 70);
         pos += 2 + bars[i]*2;
      }
    
      for (i=0; i<bc412.length; i++) 
      {
         ctx.fillText(bc412[i], i*24+20, 90);
      }
   }
   else
   {
      ctx.fillText("Nieprawidłowy", 10, 10);
      ctx.fillText("kod", 10, 25);
      ctx.fillText("Incorrect", 10, 50);
      ctx.fillText("code", 10, 65);
   }
}