// form validation function //
function validate(form) {

  var postal_code = form.postal_code.value;
  var supplier = form.supplier.value;
  var elec_usage = form.elec_usage.value;
  var gasmit = form.gasmit.value;
  var gasusage = form.gasusage.value;
  var gaskwh = form.gaskwh.value;
  var kwhshit = form.kwhshit.value;
  var postcodeRegEx = /[A-Z]{1,2}[0-9]{1,2} ?[0-9][A-Z]{2}/i;
  if(!postal_code) {
    inlineMsg('postal_code','You must enter a valid postcode.',3);
    return false;
  }
  if(!postal_code.match(postcodeRegEx)) {
    inlineMsg('postal_code','You have not typed a valid postcode.',3);
    return false;
  }
  if (!supplier) {
    inlineMsg('supplier','<strong>Error</strong><br />You must select your previous supplier',3);
	return false;
 }

if (elec_usage == "-- Select Your Energy Usage --") {
if (kwhshit == "e.g. 3300") {
    inlineMsg('elec_usage','<strong>Error</strong><br />You must select from this list<br /> or type your kWh in the field below.',3);
	return false;
	  }
 }

if (gasmit=="-- Select Supplier --") {
if (gasusage=="-- Select Your Energy Usage --") {

if (gaskwh == "e.g. 20500") {
    inlineMsg('gasusage','<strong>Error</strong><br />You must select from this list<br /> or type your kWh in the field below.',3);
	return false;
	  }
 }
}

  return true;
}


// START OF MESSAGE SCRIPT //

var MSGTIMER = 20;
var MSGSPEED = 5;
var MSGOFFSET = 3;
var MSGHIDE = 3;

// build out the divs, set attributes and call the fade function //
function inlineMsg(target,string,autohide) {
  var msg;
  var msgcontent;
  if(!document.getElementById('msg')) {
    msg = document.createElement('div');
    msg.id = 'msg';
    msgcontent = document.createElement('div');
    msgcontent.id = 'msgcontent';
    document.body.appendChild(msg);
    msg.appendChild(msgcontent);
    msg.style.filter = 'alpha(opacity=0)';
    msg.style.opacity = 0;
    msg.alpha = 0;
  } else {
    msg = document.getElementById('msg');
    msgcontent = document.getElementById('msgcontent');
  }
  msgcontent.innerHTML = string;
  msg.style.display = 'block';
  var msgheight = msg.offsetHeight;
  var targetdiv = document.getElementById(target);
  targetdiv.focus();
  var targetheight = targetdiv.offsetHeight;
  var targetwidth = targetdiv.offsetWidth;
  var topposition = topPosition(targetdiv) - ((msgheight - targetheight) / 2);
  var leftposition = leftPosition(targetdiv) + targetwidth + MSGOFFSET;
  msg.style.top = topposition + 'px';
  msg.style.left = leftposition + 'px';
  clearInterval(msg.timer);
  msg.timer = setInterval("fadeMsg(1)", MSGTIMER);
  if(!autohide) {
    autohide = MSGHIDE;  
  }
  window.setTimeout("hideMsg()", (autohide * 1000));
}

// hide the form alert //
function hideMsg(msg) {
  var msg = document.getElementById('msg');
  if(!msg.timer) {
    msg.timer = setInterval("fadeMsg(0)", MSGTIMER);
  }
}

// face the message box //
function fadeMsg(flag) {
  if(flag == null) {
    flag = 1;
  }
  var msg = document.getElementById('msg');
  var value;
  if(flag == 1) {
    value = msg.alpha + MSGSPEED;
  } else {
    value = msg.alpha - MSGSPEED;
  }
  msg.alpha = value;
  msg.style.opacity = (value / 100);
  msg.style.filter = 'alpha(opacity=' + value + ')';
  if(value >= 99) {
    clearInterval(msg.timer);
    msg.timer = null;
  } else if(value <= 1) {
    msg.style.display = "none";
    clearInterval(msg.timer);
  }
}

// calculate the position of the element in relation to the left of the browser //
function leftPosition(target) {
  var left = 0;
  if(target.offsetParent) {
    while(1) {
      left += target.offsetLeft;
      if(!target.offsetParent) {
        break;
      }
      target = target.offsetParent;
    }
  } else if(target.x) {
    left += target.x;
  }
  return left;
}

// calculate the position of the element in relation to the top of the browser window //
function topPosition(target) {
  var top = 0;
  if(target.offsetParent) {
    while(1) {
      top += target.offsetTop;
      if(!target.offsetParent) {
        break;
      }
      target = target.offsetParent;
    }
  } else if(target.y) {
    top += target.y;
  }
  return top;
}

// preload the arrow //
if(document.images) {
  arrow = new Image(7,80); 
  arrow.src = "images/msg_arrow.gif"; 
}