function setTransition(div, n){
    div.style.filter = "blur("+n+"px)"
}

var fading = false

function switchTheme(){
    if(fading)return;
    fading = true;

    if(currentTheme=="today"){
        currentTheme="2000";
    }else{
        currentTheme="today";
    }

    let LOOP_TIMES = 100;

    for(let i=0;i<=LOOP_TIMES;++i){
        setTimeout(() => {setTransition(div, i*2)}, i*5);
    }

    let div = document.getElementsByTagName("body")[0];

    setTimeout(()=>{
        setTheme(currentTheme);
    
        for(let i=0;i<=LOOP_TIMES;++i){
            setTimeout(() => {setTransition(div, (LOOP_TIMES-i)*2)}, i*5);
        }

        setTimeout(()=>fading=false, LOOP_TIMES*10)
    }, LOOP_TIMES*5)

}

function setTheme(themeName){
    for(let i of document.getElementsByClassName("css")){
        if(i.rel=="stylesheet"){
            let styleName = i.href.split("/").pop();
            i.href = "styles/"+themeName+"/"+styleName;
        }
    }
}

var currentTheme = "today";
setTheme(currentTheme);