// JavaScript Document


function estimate (proType) {
	if (!isNumber(document.getElementById('w').value) || !isNumber(document.getElementById('h').value)) {
		alert ('Please input numeric value in both fields. Unit: inches.');
		document.getElementById('est').value = "invalid input";
		return;
	}
	
	var w = parseFloat(document.getElementById('w').value);
	var h = parseFloat(document.getElementById('h').value);
	
	if (proType == "banner" && w > 100 && h > 100) {
		alert ('We produce standard banners up to 100\" in width. For bigger sizes, please contact us for details.');
		document.getElementById('est').value = "invalid input";
		return;
	}
	
	var sqPrice;
	if (proType == "vinyl")
		sqPrice = 6;
	else if (proType == "banner" && (w*h > 4608))
		sqPrice = 8;
	else
		sqPrice = 10;
	
	var est = w * h / 144 * sqPrice;
	
	if (est <= 20) est = 20;
	
	document.getElementById('est').value = Math.round(est*100)/100;
}


function isNumber (str) {
	var validChars = "0123456789.";
	var isNum = true;
	var char;
	
	if (str.length < 1)
		return false;
	
	for (i = 0; i < str.length && isNum == true; i++) {
		char = str.charAt(i);
		if (validChars.indexOf(char) == -1)
			isNum = false;
	}
	
	return isNum;
}