var cm		= 1.00;
var inch	= 0.0254;
var foot 	= 30.48;
var meter 	= 100.0;
var unit_ft	= " ft";
var unit_mt = " m";
var mode	= 'MET';

function recalculateArea() {


	var metrc 	= document.getElementById('rada').checked;
	var imper 	= document.getElementById('radb').checked;
	var x 		= parseFloat(document.getElementById('fw').value);
	var y 		= parseFloat(document.getElementById('fl').value);

	if(mode == 'MET' || !mode) {
		unitstring  = unit_mt;
		finalval	= Math.round((x * y) * 100) / 100;;
	}
	else {
		var xi 		= parseFloat(document.getElementById('fwi').value);
		var yi 		= parseFloat(document.getElementById('fli').value);
		
		blobby_x	= inch * ((x * 12) + xi);
		blobby_y	= inch * ((y * 12) + yi);
		
		unitstring 	= unit_ft;
		finalval	= Math.round((blobby_x * blobby_y) * 100) / 100;
	}
			
	document.getElementById('calc').innerHTML = addCommas(finalval) + " " + unit_mt + "²";
	document.getElementById('hidv').value = finalval;
}

function addCommas(nStr) {

	nStr += '';
	x = nStr.split('.');
	x1 = x[0];
	x2 = x.length > 1 ? '.' + x[1] : '';
	var rgx = /(\d+)(\d{3})/;
	while (rgx.test(x1)) {
		x1 = x1.replace(rgx, '$1' + ',' + '$2');
	}

	return x1 + x2;
}

function changeMode(modestr) {
	
	mode = modestr.value;

	if(mode == 'IMP') {
		// show inches
		document.getElementById('fwi').style.visibility = 'visible';
		document.getElementById('fli').style.visibility = 'visible';
		
		document.getElementById('unitw').innerHTML 	 = unit_ft;
		document.getElementById('unitl').innerHTML 	 = unit_ft;
		
		document.getElementById('unitwi').innerHTML	 = '"';
		document.getElementById('unitli').innerHTML	 = '"';
		
	}
	else {
		document.getElementById('fwi').style.visibility = 'hidden';
		document.getElementById('fli').style.visibility = 'hidden';
		
		document.getElementById('unitw').innerHTML 	 = unit_mt;
		document.getElementById('unitl').innerHTML 	 = unit_mt;
		
		document.getElementById('unitwi').innerHTML	 = ' ';
		document.getElementById('unitli').innerHTML	 = ' ';
	}
	
	recalculateArea();
}