(function () {
    "use strict";

    /* ------------------------------------------------------ small helpers */

    var root = document.documentElement;

    function remember(key, value) {
        try { localStorage.setItem(key, value); } catch (error) { /* private mode: never mind */ }
    }

    /* ------------------------------------------------------- the language */

    var description = document.querySelector('meta[name="description"]');
    var TITLE_EN = document.title;
    var TITLE_RU = "CursorLang — раскладка клавиатуры у курсора";
    var DESCRIPTION_EN = description.getAttribute("content");
    var DESCRIPTION_RU = description.getAttribute("data-content-ru");

    function applyLanguage(lang) {
        if (lang !== "ru") { lang = "en"; }

        root.setAttribute("data-lang", lang);
        root.setAttribute("lang", lang);
        document.title = lang === "ru" ? TITLE_RU : TITLE_EN;
        description.setAttribute("content", lang === "ru" ? DESCRIPTION_RU : DESCRIPTION_EN);

        var labelled = document.querySelectorAll("[data-label-en]");
        for (var i = 0; i < labelled.length; i++) {
            labelled[i].setAttribute("aria-label", labelled[i].getAttribute("data-label-" + lang));
        }

        var buttons = document.querySelectorAll("[data-set-lang]");
        for (var j = 0; j < buttons.length; j++) {
            buttons[j].setAttribute("aria-pressed",
                buttons[j].getAttribute("data-set-lang") === lang ? "true" : "false");
        }

        applyLook();
    }

    document.addEventListener("click", function (event) {
        var button = event.target.closest("[data-set-lang]");
        if (!button) { return; }

        var lang = button.getAttribute("data-set-lang");
        applyLanguage(lang);
        remember("cursorlang.lang", lang);
    });

    /* ---------------------------------------------------------- the theme */

    document.getElementById("themeBtn").addEventListener("click", function () {
        var pinned = root.getAttribute("data-theme");
        var dark = pinned
            ? pinned === "dark"
            : window.matchMedia("(prefers-color-scheme: dark)").matches;

        var next = dark ? "light" : "dark";
        root.setAttribute("data-theme", next);
        remember("cursorlang.theme", next);
    });

    /* ----------------------------------------------------- the menu button */

    var header = document.querySelector("header");
    var menuBtn = document.getElementById("menuBtn");

    function setMenu(open) {
        header.setAttribute("data-menu", open ? "open" : "closed");
        menuBtn.setAttribute("aria-expanded", open ? "true" : "false");
    }

    menuBtn.addEventListener("click", function () {
        setMenu(header.getAttribute("data-menu") !== "open");
    });

    document.addEventListener("click", function (event) {
        if (header.getAttribute("data-menu") !== "open") { return; }

        if (event.target.closest("nav.links a") || !event.target.closest("header")) {
            setMenu(false);
        }
    });

    document.addEventListener("keydown", function (event) {
        if (event.key !== "Escape" || header.getAttribute("data-menu") !== "open") { return; }

        setMenu(false);
        menuBtn.focus();
    });

    window.matchMedia("(min-width: 901px)").addEventListener("change", function (event) {
        if (event.matches) { setMenu(false); }
    });

    // Back to top, without leaving a fragment behind in the address bar
    document.addEventListener("click", function (event) {
        var back = event.target.closest('a[href="#top"]');
        if (!back) { return; }

        event.preventDefault();
        window.scrollTo({ top: 0 });
        history.replaceState(null, "", location.pathname + location.search);
    });

    /* ------------------------------------------- the border under the bar */

    var onScroll = function () {
        header.classList.toggle("scrolled", window.scrollY > 4);
    };
    window.addEventListener("scroll", onScroll, { passive: true });
    onScroll();

    /* ------------------------------------------------------- the demo above */

    var demoText = document.getElementById("demoText");
    var demoChip = document.getElementById("demoChip");
    var indicator = document.getElementById("demoIndicator");

    // A sentence typed in two layouts, the way one is
    var SCRIPT = [
        { layout: "EN", indicator: "ENG", text: "Deploy is green, " },
        { layout: "RU", indicator: "РУС", text: "можно мержить" }
    ];

    var stillMotion = window.matchMedia("(prefers-reduced-motion: reduce)");
    var timers = [];
    var typing = false;
    var onScreen = true;

    function later(fn, delay) {
        timers.push(setTimeout(fn, delay));
    }

    function stopTyping() {
        for (var i = 0; i < timers.length; i++) { clearTimeout(timers[i]); }
        timers = [];
        typing = false;
    }

    function showStill() {
        demoText.textContent = SCRIPT[0].text + SCRIPT[1].text;
        demoChip.textContent = SCRIPT[1].layout;
        demoChip.classList.remove("out");
        demoChip.hidden = false;
        indicator.textContent = SCRIPT[1].indicator;
    }

    function showChip(text) {
        demoChip.textContent = text;
        demoChip.classList.remove("out");
        demoChip.hidden = false;

        later(function () { demoChip.classList.add("out"); }, 1100);
        later(function () { demoChip.hidden = true; }, 1260);
    }

    function typeSegment(index, done) {
        if (index >= SCRIPT.length) { done(); return; }

        var segment = SCRIPT[index];
        indicator.textContent = segment.indicator;
        showChip(segment.layout);

        var position = 0;
        var step = function () {
            if (position >= segment.text.length) {
                later(function () { typeSegment(index + 1, done); }, 420);
                return;
            }

            demoText.textContent += segment.text.charAt(position);
            position++;
            later(step, 52 + Math.random() * 58);
        };

        later(step, 620);
    }

    function run() {
        demoText.textContent = "";
        demoChip.hidden = true;

        typeSegment(0, function () {
            later(run, 2600);
        });
    }

    function renderDemo() {
        if (stillMotion.matches) {
            stopTyping();
            showStill();
            return;
        }

        if (document.hidden || !onScreen) {
            stopTyping();
            return;
        }

        if (typing) { return; }

        typing = true;
        run();
    }

    stillMotion.addEventListener("change", renderDemo);
    document.addEventListener("visibilitychange", renderDemo);

    new IntersectionObserver(function (entries) {
        onScreen = entries[0].isIntersecting;
        renderDemo();
    }).observe(document.querySelector(".stage"));

    renderDemo();

    /* ------------------------------------------------ the preview below */

    var chip = document.getElementById("previewChip");
    var offset = document.getElementById("offset");
    var fontSize = document.getElementById("fontSize");
    var opacity = document.getElementById("opacity");
    var bgColor = document.getElementById("bgColor");
    var fgColor = document.getElementById("fgColor");
    var duration = document.getElementById("duration");

    var offsetVal = document.getElementById("offsetVal");
    var fontSizeVal = document.getElementById("fontSizeVal");
    var opacityVal = document.getElementById("opacityVal");
    var durationVal = document.getElementById("durationVal");

    function applyLook() {
        var onTheLeft = chip.classList.contains("left");

        chip.style.fontSize = fontSize.value + "px";
        chip.style.opacity = (opacity.value / 100).toFixed(2);
        chip.style.background = bgColor.value;
        chip.style.color = fgColor.value;
        chip.style.marginLeft = onTheLeft ? "0px" : offset.value + "px";
        chip.style.marginRight = onTheLeft ? offset.value + "px" : "0px";

        offsetVal.textContent = offset.value;
        fontSizeVal.textContent = fontSize.value;
        opacityVal.textContent = opacity.value + "%";
        durationVal.textContent = duration.value + (root.getAttribute("data-lang") === "ru" ? " мс" : " ms");
    }

    var inputs = [offset, fontSize, opacity, bgColor, fgColor, duration];
    for (var k = 0; k < inputs.length; k++) {
        inputs[k].addEventListener("input", applyLook);
    }

    document.getElementById("lookForm").addEventListener("submit", function (event) {
        event.preventDefault();
    });

    document.getElementById("side").addEventListener("click", function (event) {
        var button = event.target.closest("[data-side]");
        if (!button) { return; }

        var buttons = this.querySelectorAll("[data-side]");
        for (var i = 0; i < buttons.length; i++) {
            buttons[i].setAttribute("aria-pressed", buttons[i] === button ? "true" : "false");
        }

        var left = button.getAttribute("data-side") === "left";
        chip.classList.toggle("left", left);
        chip.classList.toggle("right", !left);
        applyLook();
    });

    var previewTimers = [];
    document.getElementById("previewBtn").addEventListener("click", function () {
        for (var i = 0; i < previewTimers.length; i++) { clearTimeout(previewTimers[i]); }
        previewTimers = [];

        chip.classList.add("out");

        previewTimers.push(setTimeout(function () {
            chip.classList.remove("out");

            previewTimers.push(setTimeout(function () {
                chip.classList.add("out");

                previewTimers.push(setTimeout(function () {
                    chip.classList.remove("out");
                }, 900));
            }, Number(duration.value)));
        }, 420));
    });

    /* ------------------------------------------------------------ the start */
    
    applyLanguage(root.getAttribute("data-lang"));
}());