var go_url="http://www.eeviewpoint.com/energy.jsp";
var co2lev = new CO2Levels();
var cacheHash = new Object();
var CacheDecider=Class.create();
CacheDecider.prototype = {
    initialize: function(rng){
        this.secondsToCache=rng;
        this.lastFetched=new Date();

    },
    keepData: function(){
        var now = new Date();
        var secondsDif = parseInt((now.getTime() - this.lastFetched.getTime()) / 1000);
        if (secondsDif < this.secondsToCache)  { return true;}
        //the data in the cache will be refreshed or re-fetched,
        //so change the lastFetched value to the current time
        this.lastFetched=new Date();
        return false;
    }
}
//http://www.parkerriver.com/energy.jsp
//http://localhost:8080/parkerriver/energy.jsp
//http://www.eeviewpoint.com/energy.jsp
window.onload=function(){
    generatePrice("oil","oilprice");
    generatePrice("fuel","fuelprice");
    generatePrice("propane",
            "propaneprice");
    $("refresh_oil").onclick=function(){ generatePrice("oil","oilprice"); }
    $("refresh_fuel").onclick=function(){ generatePrice("fuel","fuelprice"); }
    $("refresh_propane").onclick=function(){ generatePrice("propane",
            "propaneprice"); }
    $("co2_select").onchange=function(){
        $("co2ppm").
                innerHTML= co2lev.getYear($F("co2_select")); }

};

function generatePrice(energyType, elementID){
    var cacher = cacheHash[energyType];
    if(! cacher) {
        cacher = new  CacheDecider(60*60*24);    //60*60*24
        cacheHash[energyType]=cacher;
        getEnergyPrice(energyType, elementID);
        return;
    }
    if(! cacher.keepData()) { getEnergyPrice(energyType, elementID);}
}
function getEnergyPrice(energyType, elementID){

    new Ajax.Request(go_url, {method: "get",
        parameters: "priceTyp="+energyType,
        onLoading:function(){ $(elementID).innerHTML=
                              "waiting...";},
        onComplete:function(request){
            if(request.status != 200) {
                $(elementID).innerHTML="Unavailable."}   else {
                $(elementID).innerHTML=
                request.responseText;}
        }});

}