function validateLogin(f){
	if(isBlank(f.elements['walker_id'].value)){
		alert("Please enter your private code");
		document.fm.walker_id.focus();
		return false;
	}
	if(!isNumeric(f.elements['walker_id'].value, false, false)){
		alert("Your private code must be all numbers");
		document.fm.walker_id.focus();
		return false;
	}
	if(f.elements['walker_id'].value.length != 6){
		alert("Your private code must be 6 numbers long");
		document.fm.walker_id.focus();
		return false;
	}
	return true;
}

function validateStepsUpdate(f){
	if(isBlank(f.elements['steps'].value) || !isNumeric(f.elements['steps'].value, false, true)){
		alert("You must enter a number of steps");
		document.fm.steps.focus();
		return false;
	}
	return true;
}

function validateFamilyMember(f){
	if(isBlank(f.elements['family_member'].value) || isBlank(f.elements['email'].value) || isBlank(f.elements['your_name'].value)){
		alert("Please complete all three fields");
		return false;
	}
	if(!validEmail(f.elements['email'].value)){
		alert("Sorry. The email address you entered does not appear to be valid.");
		return false;
	}
	return true;
}

function changelamp(l, c, bgColor){
	var e = document.getElementById(l);
	if (c == 'R') e.src = "images/lamp_r_" + bgColor + ".gif"; else e.src="images/lamp_g_" + bgColor + ".gif";
}

function launchSlideshow(n){
	brwWindowOpen("slideshow.asp?s=" + n, returnUniqueWinId(), 720, 460, 10, 10, false, false, false, false)
}

function validateStrideLength(f){
	if(isBlank(f.elements['stride_length'].value)){
		alert("Please enter your stride length");
		return false;
	}
	
	if(f.elements['stride_length'].value < 30 || f.elements['stride_length'].value > 150){
		alert("Sorry.\n\nStride length must be between 30 and 150 centimeters");
		return false;
	}
	
	if(!isNumeric(f.elements['stride_length'].value, false, false)){
		alert("Sorry.\n\nYou must enter a numeric value for stride length");
		return false;
	}
	return true;
}
			
function isBlank(s) {
	if (s.length < 1) return true;
	for (var i = 0; i < s.length; i++) {
		var c = s.charAt(i);
		if ((c != " ") && (c != "\n") && (c != "\t")) return false;
	}
	return true;
}


function isNumeric(sText, decimalOK, signOK) {
	var validChars = "0123456789";
	if (decimalOK) validChars += ".";
	if (signOK) validChars += "+-";
	var c;
	for (i = 0; i < sText.length; i++) {
		c = sText.charAt(i);
		if (validChars.indexOf(c) == -1) return false;
	}
	return true;
}

function validEmail(s) {
	var atSymbol = s.indexOf('@')
	var dot = s.lastIndexOf('.')
	var space = s.indexOf(' ')
	var length = s.length - 1
	if ((atSymbol < 1) || (dot <= atSymbol + 1) || (dot == length ) || (space != -1)) {
		return false
	}
	return true
}

function brwWindowOpen(winURL, winName, width, height, top, left, scrollbars, menubar, toolbar, resizable){
	var properties = ""
	if (width > 0) properties += 'WIDTH=' + width + ',';
	if (height > 0) properties += 'HEIGHT=' + height + ',';
	if (top > -1) properties += 'TOP=' + top + ',';
	if (left > -1) properties += 'LEFT=' + left + ',';
	if (scrollbars) properties += 'scrollbars' + ',';
	if (menubar) properties += 'menubar' + ',';
	if (toolbar) properties += 'toolbar' + ',';
	if (resizable) properties += 'resizable';
	var newWindow = window.open(winURL, winName, properties);
	newWindow.focus();
}

function returnUniqueWinId(){
	return new Date().getTime().toString();
}