function validateOrderForm(form) { 
        var shipping = form.elements['shipping'];
        var checkedShipping = false;
        for (var j = 0 ; j< shipping.length ; ++j) {
            if (shipping[j].checked == true) {
                checkedShipping = true;
                break;
            }
        }
        if (!checkedShipping) {
            alert("Zvolte způsob dopravy!");
            return false;
        }
        
        var customer = form.elements['customer'];
        if (customer[1].checked == true) {                                                                      
            return validateRequired(form) && validateEmail(form); 
        } else {			
            return true;
        }
    }
      
   function handleShippingEvent(price, priceWithTaxes, freeShippingLimit) {
       var shipping_price = document.getElementById('shipping_price');
       var shipping_price_taxes = document.getElementById('shipping_price_taxes');
       var total_price_field = document.getElementById('total_price_field');
       var total_price_field_taxes = document.getElementById('total_price_field_taxes');              
       if (items_price>=freeShippingLimit) {
			price = 0;
			priceWithTaxes = 0;
	   }
       shipping_price.innerHTML = price + currency;
       shipping_price_taxes.innerHTML = priceWithTaxes + currency;
       total_price_field.innerHTML = items_price + price + currency;
       total_price_field_taxes.innerHTML = items_price_taxes + priceWithTaxes + currency;
   }
   
   function validateRequired(form) {
                var bValid = true;
                var focusField = null;
                var i = 0;
                var fields = new Array();
                oRequired = new required();
                for (x in oRequired) {
                	var field = form[oRequired[x][0]];
                	
                    if (field.type == 'text' ||
                        field.type == 'textarea' ||
                        field.type == 'select-one' ||
                        field.type == 'radio' ||
                        field.type == 'password') {
                        
                        var value;
						// get field's value
						if (field.type == "select-one") {
							var si = field.selectedIndex;
							value = field.options[si].value;
						} else {
							value = field.value;
						}
                        
                        if (value == '') {                 
	                        if (i == 0) {
	                            focusField = field;
	                        }
	                        fields[i++] = oRequired[x][1];
	                        bValid = false;
                        }
                    }
                }
                if (fields.length > 0) {
                   focusField.focus();
                   alert(fields.join('\n'));
                }                
                return bValid;                
            }
            
            function validateEmail(form) {
                var bValid = true;
                var focusField = null;
                var i = 0;
                var fields = new Array();
                oEmail = new email();
                for (x in oEmail) {
                    if ((form[oEmail[x][0]].type == 'text' ||
                         form[oEmail[x][0]].type == 'textarea') &&
                        (form[oEmail[x][0]].value.length > 0)) {
                        if (!checkEmail(form[oEmail[x][0]].value)) {
                            if (i == 0) {
                                focusField = form[oEmail[x][0]];
                            }
                            fields[i++] = oEmail[x][1];
                            bValid = false;
                        }
                    }
                }
                if (fields.length > 0) {
                    focusField.focus();
                    alert(fields.join('\n'));
                }                
                return bValid;
            }

       
            function checkEmail(emailStr) {
               if (emailStr.length == 0) {
                   return true;
               }
               var emailPat=/^(.+)@(.+)$/;
               var specialChars="\\(\\)<>@,;:\\\\\\\"\\.\\[\\]";
               var validChars="\[^\\s" + specialChars + "\]";
               var quotedUser="(\"[^\"]*\")";
               var ipDomainPat=/^(\d{1,3})[.](\d{1,3})[.](\d{1,3})[.](\d{1,3})$/;
               var atom=validChars + '+';
               var word="(" + atom + "|" + quotedUser + ")";
               var userPat=new RegExp("^" + word + "(\\." + word + ")*$");
               var domainPat=new RegExp("^" + atom + "(\\." + atom + ")*$");
               var matchArray=emailStr.match(emailPat);
               if (matchArray == null) {
                   return false;
               }
               var user=matchArray[1];
               var domain=matchArray[2];
               if (user.match(userPat) == null) {
                   return false;
               }
               var IPArray = domain.match(ipDomainPat);
               if (IPArray != null) {
                   for (var i = 1; i <= 4; i++) {
                      if (IPArray[i] > 255) {
                         return false;
                      }
                   }
                   return true;
               }
               var domainArray=domain.match(domainPat);
               if (domainArray == null) {
                   return false;
               }
               var atomPat=new RegExp(atom,"g");
               var domArr=domain.match(atomPat);
               var len=domArr.length;
               if ((domArr[domArr.length-1].length < 2) ||
                   (domArr[domArr.length-1].length > 3)) {
                   return false;
               }
               if (len < 2) {
                   return false;
               }
               return true;
            }
            
            function validateMask(form) {
                var bValid = true;
                var focusField = null;
                var i = 0;
                var fields = new Array();
                oMasked = new mask();
                for (x in oMasked) {
                    if ((form[oMasked[x][0]].type == 'text' ||
                         form[oMasked[x][0]].type == 'textarea' ||
                         form[oMasked[x][0]].type == 'password') &&
                        (form[oMasked[x][0]].value.length > 0)) {
                        if (!matchPattern(form[oMasked[x][0]].value, oMasked[x][2]("mask"))) {
                            if (i == 0) {
                                focusField = form[oMasked[x][0]];
                            }
                            fields[i++] = oMasked[x][1];
                            bValid = false;
                        }
                    }
                }
                if (fields.length > 0) {
                   focusField.focus();
                   alert(fields.join('\n'));
                }
                return bValid;
            }

            function matchPattern(value, mask) {
               var bMatched = mask.exec(value);
               if (!bMatched) {
                   return false;
               }
               return true;
            }