function Validator(frmname){
   this.formobj=document.forms[frmname];
    if(!this.formobj)
    {
      alert("BUG: couldnot get Form object "+frmname);
         return;
    }
    if(this.formobj.onsubmit)
    {
     this.formobj.old_onsubmit = this.formobj.onsubmit;
     this.formobj.onsubmit=null;
    }
    else
    {
     this.formobj.old_onsubmit = null;
    }
    this.formobj.onsubmit=form_submit_handler;
    this.addV = add_validation;
    this.setAddnlValidationFunction=set_addnl_vfunction;
    this.clearAllValidations = clear_all_validations;
}
function set_addnl_vfunction(functionname)
{
 this.formobj.addnlvalidation = functionname;
}
function clear_all_validations()
{
    for(var itr=0;itr < this.formobj.elements.length;itr++)
    {
         this.formobj.elements[itr].validationset = null;
    }
}
var errMsg;
function form_submit_handler(){
    errMsg = "";
    var retVal = true;
    for(var itr=0;itr < this.elements.length;itr++)
    {
         if(this.elements[itr].validationset &&
       !this.elements[itr].validationset.validate())
         {
           retVal = false;
         }
    }
   if(errMsg>""){
     alert("Correct these errors:"+errMsg);
     return false;
   }
   if(retVal && this.addnlvalidation)
    {
      str =" var ret = "+this.addnlvalidation+"()";
      eval(str);
   if(retVal && !ret) return ret;
   }
   return retVal;
}
function add_validation(itemname,descriptor,errstr)
{
    if(!this.formobj)
    {
         alert("BUG: the form object is not set properly");
         return;
    }//if
    var itemobj = this.formobj[itemname];

   if(itemobj.length && isNaN(itemobj.selectedIndex) )
   //for radio button; don't do for 'select' item
    {
         itemobj = itemobj[0];
    }    
     if(!itemobj)
    {
         alert("BUG: Couldnot get the input object named: "+itemname);
         return;
    }
   
     if(!itemobj.validationset)
    {
         itemobj.validationset = new ValidationSet(itemobj);
    }
    itemobj.validationset.add(descriptor,errstr);
}
function ValidationDesc(inputitem,desc,error)
{
   this.desc=desc;
    this.error=error;
    this.itemobj = inputitem;
    this.validate=vdesc_validate;
}
function vdesc_validate(){
  if(!validateInput(this.desc,this.itemobj,this.error)){
    this.itemobj.oldColor = this.itemobj.style.backgroundColor;
    this.itemobj.style.backgroundColor="yellow"
    this.itemobj.focus();
    this.itemobj.onkeydown = function(){this.style.backgroundColor=this.oldColor};
    this.itemobj.onclick = this.itemobj.onkeydown;
    return false;
  } else {
    this.itemobj.style.backgroundColor=this.itemobj.oldColor;
    return true;
  }
}
function ValidationSet(inputitem)
{
   this.vSet=new Array();
    this.add= add_validationdesc;
    this.validate= vset_validate;
    this.itemobj = inputitem;
}
function add_validationdesc(desc,error)
{
 this.vSet[this.vSet.length]=
  new ValidationDesc(this.itemobj,desc,error);
}
function vset_validate()
{
   for(var itr=0;itr<this.vSet.length;itr++)
      {
        if(!this.vSet[itr].validate())
           {
             return false;
           }
      }
      return true;
}

/*  checks the validity of an email address entered
*   returns true or false
*/
function validateEmail(email)
{
   var splitted = email.match("^(.+)@(.+)$");
   if(splitted == null) return false;
   if(splitted[1] != null )
   {
     var regexp_user=/^\"?[\w-_\.]*\"?$/;
     if(splitted[1].match(regexp_user) == null) return false;
   }
   if(splitted[2] != null)
   {
     var regexp_domain=/^[\w-\.]*\.[A-Za-z]{2,4}$/;
     if(splitted[2].match(regexp_domain) == null)
      {
        var regexp_ip =/^\[\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}\]$/;
        if(splitted[2].match(regexp_ip) == null) return false;
     }// if
     return true;
   }
return false;
}

function TestComparison(objValue,strCompareElement,strvalidator,strError)
{
  var bRet=true;
  var objCompare=null;
  if(!objValue.form)
  {
     alert("BUG: No Form object!");
      return false
  }
  objCompare = objValue.form.elements[strCompareElement];
  if(!objCompare)
  {
    alert("BUG: Element with name"+strCompareElement+" not found !");
    return false;
  }
  if(strvalidator != "eqelmnt" &&
         strvalidator != "neelmnt")
  {
     if(isNaN(objValue.value))
      {
        errMsg += "\n\t"+objValue.name+": Should be a number ";
        return false;
      }//if
      if(isNaN(objCompare.value))
      {
        errMsg += "\n\t"+objCompare.name+": Should be a number ";
        return false;
      }//if        
  }//if
  var cmpstr="";
  switch(strvalidator)
  {
      case "eqelmnt":
               {
                 if(objValue.value != objCompare.value)
                 {
                      cmpstr = " should be equal to ";
                    bRet = false;
                 }//if
                 break;
              }//case
         case "ltelmnt":
              {
              if(eval(objValue.value) >= eval(objCompare.value))
                    {
                     cmpstr =  " should be less than ";
                      bRet = false;                        
                    }
                break;
              }//case
         case "leelmnt":
              {
                   if(eval(objValue.value) >  eval(objCompare.value))
                    {
                     cmpstr =  " should be less than or equal to";
                      bRet = false;                        
                    }
                break;
              }//case          
         case "gtelmnt":
              {
                   if(eval(objValue.value) <=  eval(objCompare.value))
                    {
                     cmpstr =  " should be greater than";
                      bRet = false;                        
                    }
                break;
              }//case
         case "geelmnt":
              {
                   if(eval(objValue.value) < eval(objCompare.value))
                    {
                     cmpstr =  " should be greater than or equal to";
                      bRet = false;                        
                    }
                break;
              }//case
         case "neelmnt":
              {
                 if(objValue.value.length > 0 &&
                   objCompare.value.length > 0 &&
                   objValue.value == objCompare.value)
                 {
                      cmpstr = " should be different from ";
                    bRet = false;
                 }//if
                 break;              
               }              
   }//switch
  if(bRet==false)
  {
     if(!strError || strError.length==0)
      {
        strError = objValue.name + cmpstr + objCompare.value;
       }//if
      errMsg += "\n\t"+strError;
  }//if
  return bRet;
}
function TestSelMin(objValue,strMinSel,strError)
{
   var bret = true;
    var objcheck = objValue.form.elements[objValue.name];
    var chkcount =0;
    if(objcheck.length)
    {
         for(var c=0;c < objcheck.length;c++)
         {
            if(objcheck[c].checked == "1")
            {
              chkcount++;
            }//if
         }//for
    }
    else
    {
      chkcount = (objcheck.checked == "1")?1:0;
    }
    var minsel = eval(strMinSel);
    if(chkcount < minsel)
    {
         if(!strError || strError.length ==0)
          {
               strError = "Please Select atleast"+minsel+" check boxes for"+objValue.name;  
         }//if                                                              
          errMsg += "\n\t"+strError;
          bret = false;
    }
    return bret;
}

function TestDontSelectChk(objValue,chkValue,strError)
{
   var pass=true;
    var objcheck = objValue.form.elements[objValue.name];
   if(objcheck.length)
    {
         var idxchk=-1;
         for(var c=0;c < objcheck.length;c++)
         {
            if(objcheck[c].value == chkValue)
            {
              idxchk=c;
               break;
            }//if
         }//for
         if(idxchk>= 0)
         {
           if(objcheck[idxchk].checked=="1")
           {
             pass=false;
           }
         }//if
    }
    else
    {
         if(objValue.checked == "1")
         {
              pass=false;
         }//if
    }//else
    if(pass==false)
    {
    if(!strError || strError.length ==0)
        {
             strError = "Can't Proceed as you selected "+objValue.name;  
       }//if                
       errMsg += "\n\t"+strError;
     
     }
   return pass;
}

function TestRequiredInput(objValue,strError)
{
var ret = true;
   if(eval(objValue.value.length) == 0)
    {
       if(!strError || strError.length ==0)
       {
         strError = objValue.name + " : Required Field";
       }//if
       errMsg += "\n\t"+strError;
       ret=false;
    }//if
return ret;
}

function TestMaxLen(objValue,strMaxLen,strError)
{
var ret = true;
   if(eval(objValue.value.length) > eval(strMaxLen))
    {
      if(!strError || strError.length ==0)
      {
        strError = objValue.name + " : "+ strMaxLen +" characters maximum ";
      }//if
      errMsg += "\n\t"+strError + "\n\t[Current length = " + objValue.value.length + " ]";
      ret = false;
    }//if
return ret;
}

function TestMinLen(objValue,strMinLen,strError)
{
var ret = true;
   if(eval(objValue.value.length) <  eval(strMinLen))
    {
      if(!strError || strError.length ==0)
      {
        strError = objValue.name + " : " + strMinLen + " characters minimum  ";
      }//if              
      errMsg += "\n\t"+strError + "\n\t[Current length = " + objValue.value.length + " ]";
      ret = false;  
    }//if
return ret;
}

function TestInputType(objValue,strRegExp,strError,strDefaultError)
{
  var ret = true;

   var charpos = objValue.value.search(strRegExp);
    if(objValue.value.length > 0 &&  charpos >= 0)
    {
     if(!strError || strError.length ==0)
      {
        strError = strDefaultError;
     }//if
      errMsg += "\n\t"+strError + "\n\t [Error character position " + eval(charpos+1)+"]";
      ret = false;
    }//if
 return ret;
}

function TestEmail(objValue,strError)
{
var ret = true;
    if(objValue.value.length > 0 && !validateEmail(objValue.value)      )
     {
       if(!strError || strError.length ==0)
       {
          strError = objValue.name+": Enter a valid Email address ";
       }//if                                              
       errMsg += "\n\t"+strError;
       ret = false;
     }//if
return ret;
}

function TestLessThan(objValue,strLessThan,strError)
{
var ret = true;
      if(isNaN(objValue.value))
       {
         errMsg += "\n\t"+objValue.name+": Should be a number ";
         ret = false;
       }//if
       else
      if(eval(objValue.value) >=  eval(strLessThan))
       {
         if(!strError || strError.length ==0)
         {
           strError = objValue.name + " : value should be less than "+ strLessThan;
         }//if              
         errMsg += "\n\t"+strError;
         ret = false;                
        }//if  
return ret;          
}

function TestGreaterThan(objValue,strGreaterThan,strError)
{
var ret = true;
    if(isNaN(objValue.value))
     {
       errMsg += "\n\t"+objValue.name+": Should be a number ";
       ret = false;
     }//if
      else
    if(eval(objValue.value) <=  eval(strGreaterThan))
      {
        if(!strError || strError.length ==0)
        {
          strError = objValue.name + " : value should be greater than "+ strGreaterThan;
        }//if              
        errMsg += "\n\t"+strError;  
       ret = false;
     }//if  
return ret;          
}

function TestRegExp(objValue,strRegExp,strError)
{
var ret = true;
   if( objValue.value.length > 0 &&
        !objValue.value.match(strRegExp) )
    {
      if(!strError || strError.length ==0)
      {
        strError = objValue.name+": Invalid characters found ";
      }//if                                                              
      errMsg += "\n\t"+strError;
      ret = false;                  
    }//if
return ret;
}
function TestDontSelect(objValue,index,strError)
{
var ret = true;
    if(objValue.selectedIndex == null)
     {
       alert("BUG: dontselect command for non-select Item");
       ret = false;
     }
      else
    if(objValue.selectedIndex == eval(index))
     {
      if(!strError || strError.length ==0)
       {
       strError = objValue.name+": Please Select one option ";
       }//if                                                              
       errMsg += "\n\t"+strError;
       ret =  false;                                  
      }
return ret;
}

function TestSelectOneRadio(objValue,strError)
{
    var objradio = objValue.form.elements[objValue.name];
    var one_selected=false;
    for(var r=0;r < objradio.length;r++)
    {
      if(objradio[r].checked == "1")
      {
           one_selected=true;
         break;
      }
    }
    if(false == one_selected)
    {
     if(!strError || strError.length ==0)
       {
        strError = "Please select one option from "+objValue.name;
       }    
       errMsg += "\n\t"+strError;
    }
return one_selected;
}

//*  Checks each field in a form
function validateInput(strValidateStr,objValue,strError)
{
    var ret = true;
   var epos = strValidateStr.search("=");
    var  command  = "";
    var  cmdvalue = "";
    if(epos >= 0)
    {
     command  = strValidateStr.substring(0,epos);
     cmdvalue = strValidateStr.substr(epos+1);
    }
    else
    {
     command = strValidateStr;
    }

    switch(command)
    {
        case "req":
        case "required":
         {
             ret = TestRequiredInput(objValue,strError)
          break;            
         }
       case "maxlength":
        case "maxlen":
          {
                ret = TestMaxLen(objValue,cmdvalue,strError)
            break;
          }
       case "minlength":
        case "minlen":
           {
                ret = TestMinLen(objValue,cmdvalue,strError)
            break;
           }
       case "alnum":
        case "alphanumeric":
           {
                    ret = TestInputType(objValue,"[^A-Za-z0-9]",strError,
                              objValue.name+": Only alpha-numeric characters allowed ");
                   break;
           }
       case "alnum_s":
        case "alphanumeric_space":
           {
                    ret = TestInputType(objValue,"[^A-Za-z0-9\\s]",strError,
                              objValue.name+": Only alpha-numeric characters and space allowed ");
                   break;
           }            
        case "num":
        case "numeric":
           {
                ret = TestInputType(objValue,"[^0-9]",strError,
                              objValue.name+": Only digits allowed ");
               break;              
           }
       case "alphabetic":
        case "alpha":
           {
                ret = TestInputType(objValue,"[^A-Za-z]",strError,
                              objValue.name+": Only alphabetic characters allowed ");
               break;
           }
       case "alphabetic_space":
        case "alpha_s":
           {
                ret = TestInputType(objValue,"[^A-Za-z\\s]",strError,
                              objValue.name+": Only alphabetic characters and space allowed ");
               break;
           }
       case "email":
          {
                  ret = TestEmail(objValue,strError);
              break;
          }
       case "lt":
        case "lessthan":
         {
               ret = TestLessThan(objValue,cmdvalue,strError);
             break;
         }
       case "gt":
        case "greaterthan":
         {
               ret = TestGreaterThan(objValue,cmdvalue,strError);
           break;
         }
       case "regexp":
         {
               ret = TestRegExp(objValue,cmdvalue,strError);
          break;
         }
       case "dontselect":
         {
                ret = TestDontSelect(objValue,cmdvalue,strError)
            break;
         }
         case "dontselectchk":
         {
              ret = TestDontSelectChk(objValue,cmdvalue,strError)
              break;
         }
         case "selmin":
         {
              ret = TestSelMin(objValue,cmdvalue,strError);
              break;
         }
         case "selone":
         {
              ret = TestSelectOneRadio(objValue,strError);
             break;
         }          
          //Comparisons
         case "eqelmnt":
          case "ltelmnt":
         case "leelmnt":
         case "gtelmnt":
         case "geelmnt":
         case "neelmnt":
         {
             return TestComparison(objValue,cmdvalue,command,strError);
             break;
         }
   }//switch
    return ret;
}