var userAgent = navigator.userAgent.toLowerCase();
var is_opera = userAgent.indexOf('opera') != -1 && opera.version();
var is_moz = (navigator.product == 'Gecko') && userAgent.substr(userAgent.indexOf('firefox') + 8, 3);
var is_ie = (userAgent.indexOf('msie') != -1 && !is_opera) && userAgent.substr(userAgent.indexOf('msie') + 5, 3);

var $ = function (id) {
    return "string" == typeof id ? document.getElementById(id) : id;
};

var Class = {
  create: function() {
    return function() {
      this.initialize.apply(this, arguments);
    }
  }
}

Object.extend = function(destination, source) {
    for (var property in source) {
        destination[property] = source[property];
    }
    return destination;
}


var Calendar = Class.create();
Calendar.prototype = {
  initialize: function(container, options) {
	this.Container = $(container);//容器(table结构)
	this.Days = [];//日期对象列表
	
	this.SetOptions(options);
	
	this.Year = this.options.Year;
	this.Month = this.options.Month;
	this.SelectDay = this.options.SelectDay ? new Date(this.options.SelectDay) : null;
	this.onSelectDay = this.options.onSelectDay;
	this.onToday = this.options.onToday;
	this.onFinish = this.options.onFinish;	
	
	this.Draw();
  },
  //设置默认属性
  SetOptions: function(options) {
	this.options = {//默认值
		Year:			new Date().getFullYear(),//显示年
		Month:			new Date().getMonth() + 1,//显示月
		SelectDay:		null,//选择日期
		onSelectDay:	function(){},//在选择日期触发
		onToday:		function(){},//在当天日期触发
		onFinish:		function(){}//日历画完后触发
	};
	Object.extend(this.options, options || {});
  },
  //上一个月
  PreMonth: function() {
	//先取得上一个月的日期对象
	var d = new Date(this.Year, this.Month - 2, 1);
	//再设置属性
	this.Year = d.getFullYear();
	this.Month = d.getMonth() + 1;
	//重新画日历
	this.Draw();
  },  
  //下一个月
  NextMonth: function() {
	var d = new Date(this.Year, this.Month, 1);
	this.Year = d.getFullYear();
	this.Month = d.getMonth() + 1;
	this.Draw();
  },
  //画日历
  Draw: function() {
	//用来保存日期列表
	var arr = [];
	//用当月第一天在一周中的日期值作为当月离第一天的天数
	for(var i = 1, firstDay = new Date(this.Year, this.Month - 1, 1).getDay(); i <= firstDay; i++){ arr.push("&nbsp;"); }
	//用当月最后一天在一个月中的日期值作为当月的天数
	for(var i = 1, monthDay = new Date(this.Year, this.Month, 0).getDate(); i <= monthDay; i++){ arr.push(i); }
	
	var frag = document.createDocumentFragment();
	
	this.Days = [];
	
	while(arr.length > 0){
		//每个星期插入一个tr
		var row = document.createElement("tr");
		//每个星期有7天
		for(var i = 1; i <= 7; i++){
			var cell = document.createElement("td");
			cell.innerHTML = "&nbsp;";
			
			if(arr.length > 0){
				var d = arr.shift();
				cell.innerHTML = d;
				if(d > 0){
					this.Days[d] = cell;
					//判断是否今日
					if(this.IsSame(new Date(this.Year, this.Month - 1, d), new Date())){ this.onToday(cell); }
					//判断是否选择日期
					if(this.SelectDay && this.IsSame(new Date(this.Year, this.Month - 1, d), this.SelectDay)){ this.onSelectDay(cell); }
				}
			}
			row.appendChild(cell);
		}
		frag.appendChild(row);
	}
	
	//先清空内容再插入(ie的table不能用innerHTML)
	while(this.Container.hasChildNodes()){ this.Container.removeChild(this.Container.firstChild); }
	this.Container.appendChild(frag);
	
	this.onFinish();
  },
  //判断是否同一日
  IsSame: function(d1, d2) {
	return (d1.getFullYear() == d2.getFullYear() && d1.getMonth() == d2.getMonth() && d1.getDate() == d2.getDate());
  } 
};


//获取元素ID
function G(id){
    return document.getElementById(id);
};
//创建元素节点     
function GC(t){
    return document.createElement(t);
};


function closeTip(ids){ 
var ips = document.getElementById(ids); 
ips.style.display="none"; 
}

function showTip(ids,element){ 
    var ips = document.getElementById(ids); 
    var elem = document.getElementById(element); 
    var vals = fetchOffset(elem);
    if(is_moz)
    {
        ips.style.display="block"; 
        ips.style.left=vals[0]-85+"px"; 
        ips.style.top=vals[1] + elem.offsetHeight-8+"px";
    }
    else
    {
        ips.style.display="block";
        ips.style.left=event.clientX-246; 
        ips.style.top=event.clientY+document.documentElement.scrollTop+8+"px";
    }
}
function fetchOffset(obj) {
    var left_offset = obj.offsetLeft;
    var top_offset = obj.offsetTop;
    while((obj = obj.offsetParent) != null) {
        left_offset += obj.offsetLeft;
        top_offset += obj.offsetTop;
    }
    return [left_offset, top_offset];
}