Date.prototype.getWeek = function() {
  var date = new Date(this.getTime());
  date.setHours(0, 0, 0, 0);
  date.setDate(date.getDate() + 3 - (date.getDay() + 6) % 7);
  var week1 = new Date(date.getFullYear(), 0, 4);
  return 1 + Math.round(((date.getTime() - week1.getTime()) / 86400000 - 3 + (week1.getDay() + 6) % 7) / 7);
}
Date.prototype.getWeekYear = function() {
  var date = new Date(this.getTime());
  date.setDate(date.getDate() + 3 - (date.getDay() + 6) % 7);
  return date.getFullYear();
}

window.fm = (function() {
    this.headerBackground = null;
    this.originalHeaderBackground = null;
    this.defaultCoverImage = 'https://lastfm.freetls.fastly.net/i/u/174s/2a96cbd8b46e442fc41c2b86b821562f.png';
    this.indexPlayingContainer = null;
    this.indexPlayingCover = null;
    this.indexPlayingTitle = null;
    this.indexPlayingArtist = null;
    this.indexLastNp = null;

    if(sessionStorage.getItem('header-bgs') === null
        || sessionStorage.getItem('header-bgs-loaded') < Date.now() - 86400000) {
        var hXhr = new XMLHttpRequest;
        hXhr.onload = function() {
            sessionStorage.setItem('header-bgs', hXhr.responseText);
            sessionStorage.setItem('header-bgs-loaded', Date.now());
        };
        hXhr.open('GET', '/header-bgs.json');
        hXhr.send();
    }

    this.selectTextInElement = function(elem) {
        // MSIE
        if(document.body.createTextRange) {
            var range = document.body.createTextRange();
            range.moveToElementText(elem);
            range.select();
            return;
        }

        // Mozilla
        if(window.getSelection) {
            var select = window.getSelection(),
                range  = document.createRange();
            range.selectNodeContents(elem);
            select.removeAllRanges();
            select.addRange(range);
            return;
        }

        console.warn('Unable to select text.');
    };

    this.copySelectedText = function() {
        if(document.execCommand) {
            document.execCommand('copy');
            return;
        }

        console.warn('Unable to copy text.');
    };

    this.getNowListening = function(callback) {
        if(!callback)
            return;
        var xhr = new XMLHttpRequest;
        xhr.onreadystatechange = function() {
            if(xhr.readyState !== 4 || xhr.status !== 200)
                return;
            callback.call(this, JSON.parse(xhr.responseText));
        }.bind(this);
        xhr.open('GET', '/now-listening.json');
        xhr.send();
    };

    this.updateIndexNowListening = function() {
        window.fm.getNowListening(function(info) {
            if(this.indexLastNp === null
                || this.indexLastNp.url != info.url
                || this.indexLastNp.now_playing != info.now_playing) {
                if(this.indexLastNp !== null)
                    this.originalHeaderBackground = this.getRandomHeaderBackground();
                this.indexLastNp = info;
            } else return;

            this.indexPlayingContainer.classList[info.now_playing ? 'remove' : 'add']('header-now-playing-hidden');
            this.indexPlayingCover.alt = this.indexPlayingCover.src = (info.cover !== this.defaultCoverImage ? info.cover : '//now.flash.moe/resources/no-cover.png');
            this.indexPlayingTitle.textContent = this.indexPlayingTitle.title = info.name;
            this.indexPlayingTitle.href = info.url;
            this.indexPlayingArtist.textContent = this.indexPlayingArtist.title = info.artist.name;
            this.indexPlayingArtist.href = info.artist.url;
            this.switchHeaderBackground(
                info.now_playing && info.cover !== this.defaultCoverImage
                    ? this.indexPlayingCover.src
                    : this.originalHeaderBackground
            );
        });
    };

    this.getRandomHeaderBackground = function() {
        var set = JSON.parse(sessionStorage.getItem('header-bgs'));
        if(!set)
            return '/assets/errors/404.jpg';
        return set[parseInt(Math.random() * set.length)];
    };

    this.setRandomHeaderBackground = function() {
        this.switchHeaderBackground(this.getRandomHeaderBackground());
    };

    this.getCurrentHeaderBackground = function() {
        return this.headerBackground.querySelector('img').src;
    };

    this.switchHeaderBackground = function(url) {
        if(this.getCurrentHeaderBackground() === url)
            return;
        var newImg = document.createElement('img'),
            oldImg = this.headerBackground.querySelector('img');
        newImg.alt = newImg.src = url;
        newImg.style.opacity = '0';
        oldImg.style.zIndex = '-1';
        newImg.style.zIndex = '0';
        this.headerBackground.appendChild(newImg);
        newImg.onload = function() {
            setTimeout(function() {
                newImg.style.opacity = null;
                setTimeout(function() {
                    newImg.style.zIndex = null;
                    this.headerBackground.removeChild(oldImg);
                }.bind(this), 500);
            }.bind(this), 50);
        }.bind(this);
        newImg.onerror = function() {
            this.switchHeaderBackground(this.originalHeaderBackground);
        }.bind(this);
    };

    this.headerBackground = document.querySelector('.header-background');
    this.originalHeaderBackground = this.headerBackground.querySelector('img').src;

    this.initIndex = function(npInterval) {
        this.indexPlayingContainer = document.querySelector('.header-now-playing');
        this.indexPlayingCover = window.fm.indexPlayingContainer.querySelector('.header-now-playing-cover img');
        this.indexPlayingCover.onerror = function() {
            this.indexPlayingCover.src = '//now.flash.moe/resources/no-cover.png';
        }.bind(this);
        this.indexPlayingTitle = window.fm.indexPlayingContainer.querySelector('.header-now-playing-title a');
        this.indexPlayingArtist = window.fm.indexPlayingContainer.querySelector('.header-now-playing-artist a');
        this.updateIndexNowListening();
        setInterval(this.updateIndexNowListening, (npInterval || 30) * 1000);
    };

    this.initClock = function() {
        var digitalClock = document.querySelector('.php-time-digital'),
            analogClock  = document.querySelector('.php-time-analog'),
            dateZone     = document.querySelector('.php-time-date'),
            digHours     = digitalClock.querySelector('.php-time-digital-hours'),
            digSeparator = digitalClock.querySelector('.php-time-digital-separator'),
            digMinutes   = digitalClock.querySelector('.php-time-digital-minutes'),
            angHours     = analogClock.querySelector('.clock-hand-hours'),
            angMinutes   = analogClock.querySelector('.clock-hand-minutes'),
            angSeconds   = analogClock.querySelector('.clock-hand-seconds')
            dateWeek     = dateZone.querySelector('.php-date-week'),
            dateDay      = dateZone.querySelector('.php-date-day'),
            dateMonth    = dateZone.querySelector('.php-date-month'),
            dateYear     = dateZone.querySelector('.php-date-year');

        setInterval(function() {
            var time = new Date;

            var dHour = time.getHours(),
                dMin  = time.getMinutes();

            if(dHour < 10)
                dHour = '0' + dHour;
            if(dMin < 10)
                dMin = '0' + dMin;

            dateWeek.textContent = time.getWeek();
            dateDay.textContent = time.getDate();
            dateMonth.textContent = time.getMonth() + 1;
            dateYear.textContent = time.getFullYear();

            digHours.textContent = dHour;
            digMinutes.textContent = dMin;
            digSeparator.classList[time.getSeconds() % 2 ? 'add' : 'remove']('php-time-digital-separator-hidden');

            var rSec  = time.getSeconds() / 60,
                rMin  = (time.getMinutes() + Math.min(.99, rSec)) / 60,
                rHour = (time.getHours() + Math.min(.99, rMin)) / 12;

            angHours.style.setProperty('--hand-rotation', (rHour * 360).toString() + 'deg');
            angMinutes.style.setProperty('--hand-rotation', (rMin * 360).toString() + 'deg');
            angSeconds.style.setProperty('--hand-rotation', (rSec * 360).toString() + 'deg');
        }, 200);
    };

    return this;
}).call(window.fm || {});