/**
 * A plugin which enables rendering of math equations inside
 * of reveal.js slides. Essentially a thin wrapper for MathJax.
 *
 * @author Hakim El Hattab
 */
var RevealMath =
    window.RevealMath ||
    (function () {
        var options = Reveal.getConfig().math || {};
        var mathjax = options.mathjax || "https://cdnjs.cloudflare.com/ajax/libs/mathjax/2.7.0/MathJax.js";
        var config = options.config || "TeX-AMS_HTML-full";
        var url = mathjax + "?config=" + config;

        var defaultOptions = {
            messageStyle: "none",
            tex2jax: {
                inlineMath: [
                    ["$", "$"],
                    ["\\(", "\\)"],
                ],
                skipTags: ["script", "noscript", "style", "textarea", "pre"],
            },
            skipStartupTypeset: true,
        };

        function defaults(options, defaultOptions) {
            for (var i in defaultOptions) {
                if (!options.hasOwnProperty(i)) {
                    options[i] = defaultOptions[i];
                }
            }
        }

        function loadScript(url, callback) {
            var head = document.querySelector("head");
            var script = document.createElement("script");
            script.type = "text/javascript";
            script.src = url;

            // Wrapper for callback to make sure it only fires once
            var finish = function () {
                if (typeof callback === "function") {
                    callback.call();
                    callback = null;
                }
            };

            script.onload = finish;

            // IE
            script.onreadystatechange = function () {
                if (this.readyState === "loaded") {
                    finish();
                }
            };

            // Normal browsers
            head.appendChild(script);
        }

        return {
            init: function () {
                defaults(options, defaultOptions);
                defaults(options.tex2jax, defaultOptions.tex2jax);
                options.mathjax = options.config = null;

                loadScript(url, function () {
                    MathJax.Hub.Config(options);

                    // Typeset followed by an immediate reveal.js layout since
                    // the typesetting process could affect slide height
                    MathJax.Hub.Queue(["Typeset", MathJax.Hub]);
                    MathJax.Hub.Queue(Reveal.layout);

                    // Reprocess equations in slides when they turn visible
                    Reveal.addEventListener("slidechanged", function (event) {
                        MathJax.Hub.Queue(["Typeset", MathJax.Hub, event.currentSlide]);
                    });
                });
            },
        };
    })();

Reveal.registerPlugin("math", RevealMath);