function IsEmpty(aTextField) 
{
   if ((aTextField.value.length==0) || (aTextField.value==null)) 
   {
      return true;
   }
   else 
   { 
       return false; 
       }
}    

function IsInteger(aTextField)
{
   var ValidChars = "0123456789";
   var IsNumber=true;
   var Char;
   var aText = aTextField.value;
  for (i = 0; i < aText.length && IsNumber == true; i++) 
      { 
          Char = aText.charAt(i); 
          if (ValidChars.indexOf(Char) == -1) 
          {
             IsNumber = false;
          }
      }
   return IsNumber;
   
}

function emailcheck(aTextField) 
{
        var aText = aTextField.value;
        var at="@";
        var dot=".";
        var lat=aText.indexOf(at);
        var lstr=aText.length ;
        var ldot=aText.indexOf(dot);
        if (aText.indexOf(at)==-1)
        {
           return false;
        }
        if (aText.indexOf(at)==-1 || aText.indexOf(at)==0 || aText.indexOf(at)==lstr)
        {
           return false;
        }
        if (aText.indexOf(dot)==-1 || aText.indexOf(dot)==0 || aText.indexOf(dot)==lstr)
        {
            return false;
        }
        if (aText.indexOf(at,(lat+1))!=-1)
        {
            return false;
        }
        if (aText.substring(lat-1,lat)==dot || aText.substring(lat+1,lat+2)==dot)
        {
            return false;
        }
        if (aText.indexOf(dot,(lat+2))==-1)
        {
           return false;
        }
        if (aText.indexOf(" ")!=-1)
        {
           return false;
        }
        return true;
}   
    
    function trimTxt(aText) 
    {  
        var res = "";
        var c = 0;
        for (i=0; i<aText.length; i++) 
        {
          if (aText.charAt(i) != " " || c > 0) 
          {
            res += aText.charAt(i);
            if (aText.charAt(i) != " ") 
                c = res.length;
         }
      }
        return res.substr(0,c);
   }

    function validateChecker( email, sendersname, message, checker )
    {   /*
        var emailValue = email.value;
        var sendersnameValue = sendersname.value;
        var messageValue = message.value;
        var firsts = emailValue.substring(0,1) + sendersnameValue.substring(0,1) + messageValue.substring(0,1);
        if (firsts.toUpperCase() != checker.value.toUpperCase())
            return false;
            */
        if (checker.value == "172")
            return true;
        return false;
    }
    
function ValidateForm( contactForm )
{ 
     elementId = document.getElementById('emailErr');
     elementId.innerHTML = '<div id="emailErr" align="left" >&nbsp;</div>'; 
     elementId = document.getElementById('sendersnameErr');
     elementId.innerHTML = '<div id="sendersnameErr" align="left" >&nbsp;</div>'; 
     elementId = document.getElementById('messageErr');
     elementId.innerHTML = '<div id="emailErr" align="left" >&nbsp;</div>'; 

     if(IsEmpty(contactForm.email)) 
      { 
		 elementId = document.getElementById('emailErr');
         elementId.innerHTML = '<div id="emailErr" align="left" >You have not entered an Email address</div>'; 
         contactForm.email.focus(); 
         return false; 
      } 
      if (!emailcheck(contactForm.email)) 
      {
         elementId = document.getElementById('emailErr');
         elementId.innerHTML = '<div id="emailErr" align="left" >Invalid Email address entered</div>'; 
         contactForm.email.focus(); 
         return false; 
      }
      if (IsEmpty(contactForm.sendersname)) 
      { 
         elementId = document.getElementById('sendersnameErr');
         elementId.innerHTML = '<div id="sendersnameErr" align="left" >You have not entered your name</div>'; 
         contactForm.sendersname.focus(); 
         return false; 
      } 

      if (IsEmpty(contactForm.message)) 
      { 
         elementId = document.getElementById('messageErr');
         elementId.innerHTML = '<div id="messageErr" align="left" >You have not entered a message</div>'; 
         contactForm.message.focus(); 
         return false;
      } 
      if (!validateChecker( contactForm.email, contactForm.sendersname, contactForm.message, contactForm.checker )) 
      { 
         elementId = document.getElementById('checkerErr');
         elementId.innerHTML = '<div id="checkerErr" align="left" >Incorrect entry in the spam check field</div>'; 
         contactForm.checker.focus(); 
         return false; 
       }
   return true;
}