// form validation
function validate(form) {
  var name = form.name.value;
  var email = form.email.value;
  var message = form.message.value;
  var nameRegex = /^[a-zA-Z]+(([\'\,\.\- ][a-zA-Z ])?[a-zA-Z]*)*$/;
  var emailRegex = /^[\w-\.]+@([\w-]+\.)+[\w-]{2,4}$/;
  var messageRegex = new RegExp(/<\/?\w+((\s+\w+(\s*=\s*(?:".*?"|'.*?'|[^'">\s]+))?)+\s*|\s*)\/?>/gim);
  
  // revert border colors back to original
  form.name.style.borderColor = '#888';
  form.email.style.borderColor = '#888';
  form.message.style.borderColor = '#888';
  
  if(name == "") {
    errorMsg('name','you must enter your name!');
    return false;
  }
  if(!name.match(nameRegex)) {
    errorMsg('name','you have entered an invalid name!');
    return false;
  }
  if(email == "") {
    errorMsg('email','you must enter your email!');
    return false;
  }
  if(!email.match(emailRegex)) {
    errorMsg('email','you have entered an invalid email!');
    return false;
  }
  if(message == "") {
    errorMsg('message','you must enter a message!');
    return false;
  }
  if(message.match(messageRegex)) {
    errorMsg('message','you have entered an invalid message!');
    return false;
  }

  return true;
}

function errorMsg(target,string)
{
	var errorbox;
	var targetbox;
	
	// change color of targetbox
	targetbox = document.getElementById(target);
	targetbox.style.borderColor = '#900000';
	
	errorbox = document.getElementById('error');
	errorbox.innerHTML = string;
	errorbox.style.display = 'inline';
}