function switchView(ID) {
	switch(ID) {
		case 'BMI':
			window.document.getElementById('bmiKalkulackaResult').style.display = 'none';
			window.document.getElementById('bmiKalkulacka').style.display = 'block';
			break;
		case 'CAL':
			window.document.getElementById('calKalkulackaResult').style.display = 'none';
			window.document.getElementById('calKalkulacka').style.display = 'block';
			break;
		case 'ALC':
			window.document.getElementById('alcKalkulackaResult').style.display = 'none';
			window.document.getElementById('alcKalkulacka').style.display = 'block';
			break;
	}
}

function checkBMI(form) {
	document.getElementById('BMIheightError').style.display = 'none';
	document.getElementById('BMIgravityError').style.display = 'none';
	
	var height = form.height.value;
	var gravity = form.gravity.value;

	var error = false;

	height = parseInt(height);
	gravity = parseInt(gravity);

	if((height < 100 || height > 250) || isNaN(height)) {
		error = true;
		document.getElementById('BMIheightError').style.display = 'block';
	}

	if((gravity < 30 || gravity > 300) || isNaN(gravity)) {
		error = true;
		document.getElementById('BMIgravityError').style.display = 'block';
	}

	return(!error);
}

function checkCAL(form) {
	document.getElementById('CALheightError').style.display = 'none';
	document.getElementById('CALgravityError').style.display = 'none';
	document.getElementById('CALageError').style.display = 'none';
	document.getElementById('CALactivityError').style.display = 'none';
	
	var height = form.height.value;
	var gravity = form.gravity.value;
	var age = form.age.value;
	var activity = form.activity.value;

	var error = false;

	height = parseInt(height);
	gravity = parseInt(gravity);
	age = parseInt(age);

	if((height < 100 || height > 250) || isNaN(height)) {
		error = true;
		document.getElementById('CALheightError').style.display = 'block';
	}

	if((gravity < 30 || gravity > 300) || isNaN(gravity)) {
		error = true;
		document.getElementById('CALgravityError').style.display = 'block';
	}
	
	if((age < 5 || age > 120) || isNaN(age)) {
		error = true;
		document.getElementById('CALageError').style.display = 'block';
	}
	
	if(activity == 0) {
		error = true;
		document.getElementById('CALactivityError').style.display = 'block';
	}

	return(!error);
}

function checkALC(form) {
	document.getElementById('ALCgravityError').style.display = 'none';
	document.getElementById('ALCpercentError').style.display = 'none';
	document.getElementById('ALCdclError').style.display = 'none';
	document.getElementById('ALChoursError').style.display = 'none';
	
	var gravity = form.gravity.value;
	var percent = form.percent.value;
	var dcl = form.dcl.value;
	var hours = form.hours.value;

	var error = false;

	gravity = parseInt(gravity);
	percent = parseInt(percent);
	dcl = parseInt(dcl);
	hours = parseInt(hours);

	if((gravity < 30 || gravity > 300) || isNaN(gravity)) {
		error = true;
		document.getElementById('ALCgravityError').style.display = 'block';
	}
	
	if((percent < 1 || percent > 100) || isNaN(percent)) {
		error = true;
		document.getElementById('ALCpercentError').style.display = 'block';
	}
	
	if((dcl < 0 || dcl > 100) || isNaN(dcl)) {
		error = true;
		document.getElementById('ALCdclError').style.display = 'block';
	}
	
	if((hours < 1 || hours > 24) || isNaN(hours)) {
		error = true;
		document.getElementById('ALChoursError').style.display = 'block';
	}

	return(!error);
}