/*************************************************************************/
function isNum(argvalue) {
argvalue = argvalue.toString();

if (argvalue.length == 0)
return false;

for (var n = 0; n < argvalue.length; n++)
if (argvalue.substring(n, n+1) < "0" || argvalue.substring(n, n+1) > "9")
return false;

return true;
}

/*************************************************************************/
function ValidateFields(ObjForm){
  
  if (isNum(ObjForm.Days.value) == false ) {
	ObjForm.Days.value = 1;				   
  }
  
  if (isNum(ObjForm.NumWords.value) == false ) {
	ObjForm.NumWords.value = 0;				   
  }

  if (ObjForm.Days.value == 0){
    ObjForm.Days.value = 1;
  }
  
  if ( ObjForm.NumWords.value / ObjForm.Days.value > 5000){   
	if ( (ObjForm.NumWords.value / 5000) > ObjForm.Days.value ){
	  ObjForm.Days.value = parseInt(ObjForm.Days.value) + 1 ;
	}  
  }
}				 


function CalculatePrice(ObjForm){   
  var N;
  var P;
  var MinTariff;
  var LimitDay;
  
  ValidateFields(ObjForm);
  
  
  /* ---- Min Tariff ---- */
  MinTariff = 150;
  /* -------------------- */				   				   
  
  /* ---- Day Limit  ---- */
  LimitDay = 7;
  /* -------------------- */
  
 
  if (ObjForm.Days.value < LimitDay){
	N = ObjForm.NumWords.value / ObjForm.Days.value;    
  }else{
    N = ObjForm.NumWords.value / LimitDay;	
  }
  				   				  	   
  P = ObjForm.W.value * ObjForm.NumWords.value;				   
				   
  if (N <= 3500){
    T = 0;
  }else if (N > 3500 && N < 4000){
    T = P / 5; // 20%
  }else{
    T = P / 2; // 50%
  } 
			       
  P = P + T;
  P = P.toFixed(2);				   		   
				   
  if ( P >= MinTariff ){
    ObjForm.Price.value = P;
  }else{
	ObjForm.Price.value = MinTariff.toFixed(2);
  }
				   
}