/***
这是GreaseMonkey脚本的自动升级辅助用代码。详见http://npchen.blogspot.com/2008/12/greasemonkey.html
***/

Function.prototype.bind = function(object){
  var __method=this;
  return function(){__method.apply(object,arguments);}
};

function CGM_getValue(v, utf8_defaultV) {
    var t = GM_getValue(v);
    if (t==undefined) return utf8_defaultV;
    else return decodeURIComponent(t);
}

function CGM_setValue(n, v) {
    GM_setValue(n, encodeURIComponent(v));
}

var Updater = function (script) {
   this.script    = script;
   this.key = 'update_lastChecked'; //GM_setValue前面会自动添加namespace和script name, key可用常量
   this.lastCheck = CGM_getValue(this.key, 0); 
   this.dateTime  = Date.now()/1000;
   this.hoursToCheck = 10; 
   GM_registerMenuCommand("\u66F4\u65B0"+this.script.name+"\u811A\u672C", this.update.bind(this));
}   

//用这个方法修改默认的检查频率
Updater.prototype.setHoursToCheck = function(t){ 
   this.hoursToCheck = t;
}; 

Updater.prototype.getVersion = function(meta){
   var ver = meta.match(/\/\/\s*@version\s*(\d.*)/);
   return (ver===null) ? '0' : ver[1];
};

Updater.prototype.getReason = function(meta){
   var reason = meta.substring(meta.search(/\/\*\s*@reason/im));
   reason = reason.substring(0, reason.search(/@end\s*\*\//im));
   reason = reason.replace(/\/\*\s*@reason/, "");
   return reason;
};

Updater.prototype.versionCompare = function(v1, v2){
  var a1 = v1.split('.'); 
  var a2 = v2.split('.'); 
  do {
     var t1 = Number(a1.shift());
     var t2 = Number(a2.shift());
     if (t1 == t2) continue;
     return (t1>t2)
  } while((a1.length>0) && (a2.length>0))
  return (a1.length>0)
};

Updater.prototype.update = function( ){
   this.meta_js = "http://userscripts.org/scripts/source/"+this.script.id+".meta.js";
   this.user_js = "http://userscripts.org/scripts/source/"+this.script.id+".user.js";
   GM_xmlhttpRequest({
        method: 'GET',
        url: this.meta_js,
        onreadystatechange: this.process.bind(this)
    });
};

Updater.prototype.process = function(response){
   this.result=false;
   CGM_setValue(this.key, this.dateTime);
   if ((response.readyState == 4) && (response.status == 200)) {
      var ver = this.getVersion(response.responseText); 
      var reason = this.getReason(response.responseText); 
      if (this.versionCompare(ver, this.script.version)){
            alert(this.script.name+'\u66F4\u65B0\u81F3\u7248\u672Cv.'+ver+'\n\n'+reason); //更新至版本
            this.result=true;            
            window.status=this.script.name+'\u811A\u672C\u6709\u66F4\u65B0';     //脚本有更新           
            window.location.href = this.user_js;
      }
    }
    if (!this.result) window.status=this.script.name+'\u811A\u672C\u6CA1\u6709\u66F4\u65B0';
}
    
Updater.prototype.check = function( ){
   var dateDiff = this.dateTime - this.lastCheck;
   if ((dateDiff > (3600*this.hoursToCheck) ) || (dateDiff < 0)) {	//每隔hoursToCheck检查一次. 默认是10小时
      this.update();
   }
};