// JavaScript Document
var MONTH_ACTIVE = 1;

function changeMonth(type){
	var index = -1;
	
	if(type == 'prev'){
		index = MONTH_ACTIVE-1;
		if(index < 1){
			index = document.getElementById("number_months").value;
		}
	} else if(type == 'next'){
		index = MONTH_ACTIVE+1;
		if(index > document.getElementById("number_months").value){
			index = 1;
		}
	}
	
	(document.getElementById("calendar_"+MONTH_ACTIVE)).className = "hide";
	(document.getElementById("calendar_"+index)).className = "show";
	MONTH_ACTIVE = index;
}