import { withPluginApi } from "discourse/lib/plugin-api";
import loadScript from "discourse/lib/load-script";

function ensureKaTeX() {
  return loadScript("/plugins/discourse-math/katex/katex.min.js").then(() => {
    return loadScript("/plugins/discourse-math/katex/katex.min.css", { css: true }).then(() => {
      return loadScript("/plugins/discourse-math/katex/mhchem.min.js")
    })
  })
}

function decorate(elem, isPreview) {
  const $elem = $(elem);
  const displayMode = elem.tagName === 'DIV';

  if ($elem.data("applied-katex")) {
    return;
  }
  $elem.data("applied-katex", true);

  if ($elem.hasClass("math")) {
    const text = $elem.text();
    $elem.text('');
    window.katex.render(text, elem, { displayMode });
  }
}

function katex($elem) {
  if (!$elem || !$elem.find) {
    return;
  }

  const mathElems = $elem.find(".math");

  if (mathElems.length > 0) {
    const isPreview = $elem.hasClass("d-editor-preview");

    ensureKaTeX().then(() => {
      mathElems.each((idx, elem) => decorate(elem, isPreview));
    });
  }
}

function initializeMath(api) {
  api.decorateCooked(function(elem) {
    katex(elem);
  });
}

export default {
  name: "apply-math-katex",
  initialize(container) {
    const siteSettings = container.lookup("site-settings:main");
    if (siteSettings.discourse_math_enabled && siteSettings.discourse_math_provider === 'katex') {
      withPluginApi("0.5", function(api) {
        initializeMath(api);
      });
    }
  }
};