var errormsg="";


function clearError()//goi ham` nay truoc
{
   errormsg="";
}
function checkEmail(email)
{
   var at1      =  email.indexOf("@");
   var at2      =  email.lastIndexOf("@");
   var dot     =  email.indexOf(".");
   var space   =  email.indexOf(" ");
   if((at1!=-1)&&
      (at1!=0)&&
      (at2==at1)&&
      (dot!=-1)&&
      (dot>at1+1)&&
      (dot<email.length-1)&&
      (space==-1))
   {
      return true;
   }
   else
   {
      errormsg=errormsg+"- e-mail invalid.\n";
      return false;
   }
}
function checkDate(dd,mm,yyyy,name)
{
   result=true;
   if(!isNaN(yyyy)&&(yyyy!="")&&(yyyy<10000))	
   {
      if( (mm=="02") && ((dd=="30")||(dd=="31")) )
         result=false;
      if( (mm=="02") && (dd=="29") && (yyyy%4>0) )
         result=false;
      if( ((mm=="04")||(mm=="06")||(mm=="09")||(mm=="11")) && (dd=="31") )
         result=false;
   }
   else
   {
      result=false;
   }
   if(result==false)
      errormsg=errormsg+"- "+name+" mauvais format.\n"	
   return result;
}
function checkInterval(dstart,mstart,ystart,names,dend,mend,yend,namee)
{
   var re=true;
   re=checkDate(dstart,mstart,ystart,names)&&checkDate(dend,mend,yend,namee);   
   if(re)
   {
      var yyyy=yend-ystart;
      if(yyyy>0)
	 re=true;
      else if(yyyy==0)
      {
         var mm=mend-mstart;
         if(mm>0)
            re=true;
         else if(mm==0)
         {
            var dd=dend-dstart;
	    if(dd>0)
	       re=true;
            else
               re=false; 		 
         }
         else
	    re=false; 
      }
      else
         re=false; 	
   }
   if(re==false)
      errormsg=errormsg+"- Interval time is illegal .\n";
   
   return re; 
}
function checkTextField(str,name)
{
	if(str=="")
		errormsg=errormsg+"- "+name+" cannot be empty.\n";
}

function checkChoice(val,name)
{
	if(val=="")
		errormsg=errormsg+"- "+name+" must select one .\n"; 
}

function checkIsNum(val,name)
{
	if((val!="")&&(!isNaN(val)))
		return true;
	else
	{	
		errormsg=errormsg+"- "+name+" phai nhap bang con so. \n";
	}
}

function checkPasswordLength(pass, len)
{
	if (pass.length < len)
	{
		errormsg=errormsg+"- M?t kh?u ph?i t? " + len + " ký t? tr? lên. \n";
		return false;
	}
	return true;
}
// check pass and retype pass is the same?
function checkDupPass(pass,retypepass)
{
	if((pass!="")&&(retypepass!="")&&(retypepass == pass) )
		return true;
	else
	{	
		errormsg=errormsg+"- password invalid. \n";
		return false;
	}

}
function checkAll()
{
	if(errormsg!="")
	{
		alert(" \n\n"+errormsg);
		return false;
	}
	else
		return true;
}