window.onload = function () {

	showHideFieldsets();
		  
	document.getElementById('input-num_of_recips').onchange = function () {
		num_of_recips = document.getElementById('input-num_of_recips').value; 
		showHideFieldsets();
	}	
}

function showHideFieldsets() {
	
	var arrFieldsets = document.getElementsByTagName('fieldset'); 
	var num; 
	
	for (var i=0; i < arrFieldsets.length; i++) {
		
		if (arrFieldsets[i].id.substring(0, 15) == 'fieldset-recip_') {
			num = arrFieldsets[i].id.substring(15);
			num = parseInt(num);
			
			if (num <= num_of_recips) {
				arrFieldsets[i].style.display = 'block';
			} else {
				arrFieldsets[i].style.display = 'none';
			}
			
			enableDisableInputs(arrFieldsets[i].id);
		}
	}
}

function enableDisableInputs(fieldset_id) {

	var arrInputs = document.getElementById(fieldset_id).getElementsByTagName('input');
	var arrTextareas = document.getElementById(fieldset_id).getElementsByTagName('textarea');
	var num; 
	
	for (var i=0; i < arrInputs.length; i++) {
	
		if (arrInputs[i].id.substring(0, 12) == 'input-recip-') {
			num = arrInputs[i].id.substring(12);
			num = parseInt(num);
			
			if (num <= num_of_recips) {
				arrInputs[i].disabled = false;
			} else {
				arrInputs[i].disabled = true;
			}
		}
	}
	
	for (var i=0; i < arrTextareas.length; i++) {
	
		if (arrTextareas[i].id.substring(0, 12) == 'input-recip-') {
			num = arrTextareas[i].id.substring(12);
			num = parseInt(num);
			
			if (num <= num_of_recips) {
				arrTextareas[i].disabled = false;
			} else {
				arrTextareas[i].disabled = true;
			}
		}
	}
}