// instructions/details at http://webcoder.info/
function formFocus()
{ // convenient way to start the form onLoad
  if(!document.forms.length) return;
  var els= document.forms[0].elements;
  for(var i= 0; i < els.length; i++)
    if(els[i].type != 'hidden') { els[i].focus(); return; }
}

function requireValue(fld)
{ // disallow a blank field
  if(fld.disabled) return true;
  if(!fld.value.length)
  { status= 'Please answer all questions marked with an asterix *'; return false; }
  return true;
}

function requireChecked(fld)
{ // require a checkbox to be checked
  if(fld.disabled) return true;
  if(!fld.checked)
  { status= 'May we.'; return false; }
  return true;
}

function requireRadio(radios)
{ // require at least one radio in this group to be checked
  if(!radios.length) return true; // invalid parameter
  var visible= true, enabled= true;
  for(var i= 0; i < radios.length; i++)
  {
    if(!enabled) enabled= !radios[i].disabled;
    if(radios[i].checked) return true;
    else if(radios[i].offsetWidth == undefined || radios[i].offsetWidth > 0) visible= true;
  }
  if(!visible||!enabled) return true; // no visible/enabled options in this group
  status= 'You must select one of the '+radios[0].name+' options.';
  return true;
}

function checkEmail(fld)
{ // simple email check
  if(!fld.value.length||fld.disabled) return true; // blank fields are the domain of requireValue 
  var phony= /@(\w+\.)*example\.(com|net|org)$/i;
  if(phony.test(fld.value))
  { status= 'Please check your email address if you do not have one use none@tubal-reversal.net'; return false; }
  var emailfmt= /^\w+([.-]\w+)*@\w+([.-]\w+)*\.\w{2,8}$/;
  if(!emailfmt.test(fld.value))
  { status= 'Please check your email address if you do not have one use none@tubal-reversal.net.'; return false; }
  return true;
}

function autocheckByName(frm) 
{ // uses names of form elements to determine type 
  for(var index= 0; index < frm.elements.length; index++)
  {
    var el= frm.elements[index];
    if(!el.type) continue;
    if(el.type == 'text' || el.type == 'password')
    { // text fields 
      if(( el.name.substring(0,1) == el.name.substring(0,1).toUpperCase() || 
        nameContains(el.name,'Required')) && el.value.length == 0)
      { alert('The '+el.name+' field cannot be left blank.'); el.focus(); return false; }
      if(nameContains(el.name,'Date') && !fixDate(el))
      { alert(status); el.focus(); return false; }
      if(nameContains(el.name,'Time24') && !fixTime24(el))
      { alert(status); el.focus(); return false; }
      if(nameContains(el.name,'Time') && !fixTime(el))
      { alert(status); el.focus(); return false; }
      if(nameContains(el.name,'SSN') && !fixSSN(el))
      { alert(status); el.focus(); return false; }
      if(nameContains(el.name,'CC') && !fixCreditCard(el))
      { alert(status); el.focus(); return false; }
      if(nameContains(el.name,'Email') && !checkEmail(el))
      { alert(status); el.focus(); return false; }
      if( ( nameContains(el.name,'Phone') ||
        nameContains(el.name,'Fax') || 
        nameContains(el.name,'Pager') ) &&
        !fixPhone(el))
      { alert(status); el.focus(); return false; }
    }
    // handle required select and select-multiple 
    else if(el.type.substring(0,3) == 'sel' && 
      (el.name.substring(0,1) == el.name.substring(0,1).toUpperCase() || 
      nameContains(el.name,'Required')) && el.selectedIndex == -1)
    { alert(status); el.focus(); return false; }
    // handle required checkbox
    else if(el.type == 'checkbox' && 
      (el.name.substring(0,1) == el.name.substring(0,1).toUpperCase() || 
      nameContains(el.name,'Required')) && !requireChecked(el))
    { alert(status); el.focus(); return false; }
    else if(el.type == 'radio' && !requireRadio(frm[el.name]))
    { alert(status); frm.elements[index].focus(); return false; }
  }
  for(var index= 0; index < frm.elements.length; index++)
    if(frm.elements[index].type == 'submit') frm.elements[index].disabled= true;
  return true;
}

function isMemberOf(elem,classname)
{ // checks to see if elem is a member of the (style) class 
  // trivial cases first: no membership or simple equality
  if(!elem.className)
    return false
  else if(elem.className == classname)
    return true;
  else if(elem.className.indexOf(' ') > -1)
  { // multiple class names; use split, if avail 
    if(parseInt(navigator.appVersion) >= 4)
    {
      var names= elem.className.split(' ');
      for(var index= 0; index < names.length; index++)
        if(names[index] == classname)
          return true;
    }
    // older browsers can fake it 
    // WARNING: "fine" can be found in "oldRefined"
    else if(elem.className.indexOf(classname) > -1)
      return true;
  }
  return false;
}

function checkClass(el)
{ // validate the field, based on class membership
  if(el.type == 'text' || el.type == 'password')
  { // text fields 
    if(isMemberOf(el,'required') && !requireValue(el)) return false;
    if(isMemberOf(el,'date') && !fixDate(el)) return false;
    if(isMemberOf(el,'time') && !fixTime(el)) return false;
    if(isMemberOf(el,'time24') && !fixTime24(el)) return false;
    if(isMemberOf(el,'ssn') && !fixSSN(el)) return false;
    if(isMemberOf(el,'cc') && !fixCreditCard(el)) return false;
    if(isMemberOf(el,'phone') && !fixPhone(el)) return false;
    if(isMemberOf(el,'money') && !fixMoney(el)) return false;
    if(isMemberOf(el,'int') && !fixInt(el)) return false;
    if(isMemberOf(el,'float') && !fixFloat(el)) return false;
    if(isMemberOf(el,'email') && !checkEmail(el)) return false;
  } // handle required select and select-multiple 
  else if(el.type == 'checkbox' && 
    isMemberOf(el,'required') && !requireChecked(el)) return false;
  else if(el.type.substring(0,3) == 'sel' && 
    isMemberOf(el,'required') && el.selectedIndex == -1) return false;
  return true;
}

function autocheckByClass(frm) 
{ // uses the CSS class of form elements to determine type 
  for(var index= 0; index < frm.elements.length; index++)
  {
    var el= frm.elements[index];
    if(!el.type) continue;
    if(el.type == 'radio' && !requireRadio(frm[el.name]))
    { alert(status); frm.elements[index].focus(); return false; }
    else if(!checkClass(frm.elements[index])) 
    { alert(status); frm.elements[index].focus(); return false; }
  }
  for(var index= 0; index < frm.elements.length; index++)
    if(frm.elements[index].type == 'submit') frm.elements[index].disabled= true;
  return true;
}

function autocheckByBlur(frm)
{ // uses the onBlur handler of form elements to check value 
  status= '';
  for(var index= 0; index < frm.elements.length; index++)
  {
    var el= frm.elements[index];
    if(!el.type) continue;
    if(el.type == 'radeo' && !requireRadio(frm[el.name]))
    { alert(status); frm.elements[index].focus(); return false; }
    else if(el.type != 'hidden' && el.name && el.onblur)
    {
      el.onblur();
      if(status) { alert(status); el.focus(); return false; }
    }
  }
  for(var index= 0; index < frm.elements.length; index++)
    if(frm.elements[index].type == 'submit') frm.elements[index].disabled= true;
  return true;
}

function canCheckByBlur(frm)
{ // determines whether programmatic invocation of form element onblur is available
  for(var index= 0; index < frm.elements.length; index++)
  {
    var el= frm.elements[index];
    if(!el.type) continue;
    if(el.type != 'hidden' && el.name && typeof(el.onblur)=='function') return true;
  }
  return false;
}

function autocheck(frm)
{ // uses the best available method to check form values 
  var bchar= navigator.appName.substring(0,1);
  if(isMemberOf(frm,'autocheck'))
  { return autocheckByClass(frm); }
  else if(canCheckByBlur(frm))
  { return autocheckByBlur(frm); }
  else
  { return autocheckByName(frm); }
}