var newwindow;

function popup(url)
{
	newwindow=window.open(url,'GK Tools Location','height=450,width=425');
	if (window.focus) {newwindow.focus()}
	
}

//Utility function courtesy of http://www.php-mysql-tutorial.com
function trim(str)
{
   return str.replace(/^\s+|\s+$/g,'');
}

//Regex function to validate email address courtesy of http://www.php-mysql-tutorial.com
function isEmail(str){
   var regex = /^[-_.a-z0-9]+@(([-_a-z0-9]+\.)+(ad|ae|aero|af|ag|ai|al|am|an|ao|aq|ar|arpa|as|at|au|aw|az|ba|bb|bd|be|bf|bg|bh|bi|biz|bj|bm|bn|bo|br|bs|bt|bv|bw|by|bz|ca|cc|cd|cf|cg|ch|ci|ck|cl|cm|cn|co|com|coop|cr|cs|cu|cv|cx|cy|cz|de|dj|dk|dm|do|dz|ec|edu|ee|eg|eh|er|es|et|eu|fi|fj|fk|fm|fo|fr|ga|gb|gd|ge|gf|gh|gi|gl|gm|gn|gov|gp|gq|gr|gs|gt|gu|gw|gy|hk|hm|hn|hr|ht|hu|id|ie|il|in|info|int|io|iq|ir|is|it|jm|jo|jp|ke|kg|kh|ki|km|kn|kp|kr|kw|ky|kz|la|lb|lc|li|lk|lr|ls|lt|lu|lv|ly|ma|mc|md|mg|mh|mil|mk|ml|mm|mn|mo|mp|mq|mr|ms|mt|mu|museum|mv|mw|mx|my|mz|na|name|nc|ne|net|nf|ng|ni|nl|no|np|nr|nt|nu|nz|om|org|pa|pe|pf|pg|ph|pk|pl|pm|pn|pr|pro|ps|pt|pw|py|qa|re|ro|ru|rw|sa|sb|sc|sd|se|sg|sh|si|sj|sk|sl|sm|sn|so|sr|st|su|sv|sy|sz|tc|td|tf|tg|th|tj|tk|tm|tn|to|tp|tr|tt|tv|tw|tz|ua|ug|uk|um|us|uy|uz|va|vc|ve|vg|vi|vn|vu|wf|ws|ye|yt|yu|za|zm|zw)|(([0-9][0-9]?|[0-1][0-9][0-9]|[2][0-4][0-9]|[2][5][0-5])\.){3}([0-9][0-9]?|[0-1][0-9][0-9]|[2][0-4][0-9]|[2][5][0-5]))$/i;

	return regex.test(str);
}

//Validates contact form info before allowing submission
function checkForm(){
				 var emailerror;
				 var commenterror;
				 
				 //Check email address entered is valid and not empty 
				 var email = document.getElementById("email").value;
				 
				 if(trim(email) == "" || trim(email) == null || !isEmail(trim(email))){
				 					emailerror = true;
									
				 }
				 //Check message entered is not empty
				 var comment = document.getElementById("comment").value;
				 if(trim(comment) == "" || trim(comment) == null){
				 						commenterror = true;
				 }
				 
				 //determine error msg to show
				 if(emailerror && commenterror){			 				
							alert("Please check your email address is correct and enter a message before clicking the Submit Comment button.");
				 			return false;
				 }
				 else if(emailerror){
				 			alert("Please check your email address is correct and try again.");
				 			return false;
				 }
				 else if(commenterror){
				 			alert("Please enter a comment before clicking the Submit Comment button.");
				 			return false;
				 }
				 else{
				 			return true;
				 }
				
}