[mod] theme/simple: migrate codebase to TypeScript

TypeScript is a superset of JavaScript, converting the entire theme to
TypeScript allows us to receive much more feedback on possible issues made in
package updates or our own typos, furthermore, it allows to transpile properly
to lower specs. This PR couldn't be done in smaller commits, a lot of work
needed to make everything *work properly*:

- A browser baseline has been set that requires minimum **Chromium 93, Firefox
  92 and Safari 15** (proper visuals/operation on older browser versions is not
  guaranteed)
- LightningCSS now handles minification and prefix creation for CSS.
- All hardcoded polyfills and support for previous browser baseline versions
  have been removed.
- Convert codebase to TypeScript.
- Convert IIFE to ESM, handling globals with IIFE is cumbersome, ESM is the
  standard for virtually any use of JS nowadays.
- Vite now builds the theme without the need for `vite-plugin-static-copy`.
- `searxng.ready` now accepts an array of conditions for the callback to be
  executed.
- Replace `leaflet` with `ol` as there were some issues with proper Vite
  bundling.
- Merged `head` with `main` script, as head was too small now.
- Add `assertElement` to properly check the existence of critical DOM elements.
- `searxng.on` renamed to `searxng.listen` with some handling improvements.

client/simple/src/js/main/results.ts

@@ -0,0 +1,181 @@
+import "../../../node_modules/swiped-events/src/swiped-events.js";
+import { assertElement, searxng } from "./00_toolkit.ts";
+
+const loadImage = (imgSrc: string, onSuccess: () => void): void => {
+  // singleton image object, which is used for all loading processes of a detailed image
+  const imgLoader = new Image();
+
+  // set handlers in the on-properties
+  imgLoader.onload = () => {
+    onSuccess();
+  };
+
+  imgLoader.src = imgSrc;
+};
+
+searxng.ready(
+  () => {
+    const imageThumbnails = document.querySelectorAll<HTMLImageElement>("#urls img.image_thumbnail");
+    for (const thumbnail of imageThumbnails) {
+      if (thumbnail.complete && thumbnail.naturalWidth === 0) {
+        thumbnail.src = `${searxng.settings.theme_static_path}/img/img_load_error.svg`;
+      }
+
+      thumbnail.onerror = () => {
+        thumbnail.src = `${searxng.settings.theme_static_path}/img/img_load_error.svg`;
+      };
+    }
+
+    const copyUrlButton = document.querySelector<HTMLButtonElement>("#search_url button#copy_url");
+    copyUrlButton?.style.setProperty("display", "block");
+
+    searxng.listen("click", ".btn-collapse", function (this: HTMLElement) {
+      const btnLabelCollapsed = this.getAttribute("data-btn-text-collapsed");
+      const btnLabelNotCollapsed = this.getAttribute("data-btn-text-not-collapsed");
+      const target = this.getAttribute("data-target");
+
+      if (!target || !btnLabelCollapsed || !btnLabelNotCollapsed) return;
+
+      const targetElement = document.querySelector<HTMLElement>(target);
+      assertElement(targetElement);
+
+      const isCollapsed = this.classList.contains("collapsed");
+      const newLabel = isCollapsed ? btnLabelNotCollapsed : btnLabelCollapsed;
+      const oldLabel = isCollapsed ? btnLabelCollapsed : btnLabelNotCollapsed;
+
+      this.innerHTML = this.innerHTML.replace(oldLabel, newLabel);
+      this.classList.toggle("collapsed");
+
+      targetElement.classList.toggle("invisible");
+    });
+
+    searxng.listen("click", ".media-loader", function (this: HTMLElement) {
+      const target = this.getAttribute("data-target");
+      if (!target) return;
+
+      const iframeLoad = document.querySelector<HTMLIFrameElement>(`${target} > iframe`);
+      assertElement(iframeLoad);
+
+      const srctest = iframeLoad.getAttribute("src");
+      if (!srctest) {
+        const dataSrc = iframeLoad.getAttribute("data-src");
+        if (dataSrc) {
+          iframeLoad.setAttribute("src", dataSrc);
+        }
+      }
+    });
+
+    searxng.listen("click", "#copy_url", async function (this: HTMLElement) {
+      const target = this.parentElement?.querySelector<HTMLPreElement>("pre");
+      assertElement(target);
+
+      await navigator.clipboard.writeText(target.innerText);
+      const copiedText = this.dataset.copiedText;
+      if (copiedText) {
+        this.innerText = copiedText;
+      }
+    });
+
+    searxng.selectImage = (resultElement: Element): void => {
+      // add a class that can be evaluated in the CSS and indicates that the
+      // detail view is open
+      const resultsElement = document.getElementById("results");
+      resultsElement?.classList.add("image-detail-open");
+
+      // add a hash to the browser history so that pressing back doesn't return
+      // to the previous page this allows us to dismiss the image details on
+      // pressing the back button on mobile devices
+      window.location.hash = "#image-viewer";
+
+      searxng.scrollPageToSelected?.();
+
+      // if there is no element given by the caller, stop here
+      if (!resultElement) return;
+
+      // find image element, if there is none, stop here
+      const img = resultElement.querySelector<HTMLImageElement>(".result-images-source img");
+      if (!img) return;
+
+      // <img src="" data-src="http://example.org/image.jpg">
+      const src = img.getAttribute("data-src");
+      if (!src) return;
+
+      // use thumbnail until full image loads
+      const thumbnail = resultElement.querySelector<HTMLImageElement>(".image_thumbnail");
+      if (thumbnail) {
+        img.src = thumbnail.src;
+      }
+
+      // load full size image
+      loadImage(src, () => {
+        img.src = src;
+        img.onerror = () => {
+          img.src = `${searxng.settings.theme_static_path}/img/img_load_error.svg`;
+        };
+
+        img.removeAttribute("data-src");
+      });
+    };
+
+    searxng.closeDetail = (): void => {
+      const resultsElement = document.getElementById("results");
+      resultsElement?.classList.remove("image-detail-open");
+
+      // remove #image-viewer hash from url by navigating back
+      if (window.location.hash === "#image-viewer") {
+        window.history.back();
+      }
+
+      searxng.scrollPageToSelected?.();
+    };
+
+    searxng.listen("click", ".result-detail-close", (event: Event) => {
+      event.preventDefault();
+      searxng.closeDetail?.();
+    });
+
+    searxng.listen("click", ".result-detail-previous", (event: Event) => {
+      event.preventDefault();
+      searxng.selectPrevious?.(false);
+    });
+
+    searxng.listen("click", ".result-detail-next", (event: Event) => {
+      event.preventDefault();
+      searxng.selectNext?.(false);
+    });
+
+    // listen for the back button to be pressed and dismiss the image details when called
+    window.addEventListener("hashchange", () => {
+      if (window.location.hash !== "#image-viewer") {
+        searxng.closeDetail?.();
+      }
+    });
+
+    const swipeHorizontal = document.querySelectorAll<HTMLElement>(".swipe-horizontal");
+    for (const element of swipeHorizontal) {
+      searxng.listen("swiped-left", element, () => {
+        searxng.selectNext?.(false);
+      });
+
+      searxng.listen("swiped-right", element, () => {
+        searxng.selectPrevious?.(false);
+      });
+    }
+
+    window.addEventListener(
+      "scroll",
+      () => {
+        const backToTopElement = document.getElementById("backToTop");
+        const resultsElement = document.getElementById("results");
+
+        if (backToTopElement && resultsElement) {
+          const scrollTop = document.documentElement.scrollTop || document.body.scrollTop;
+          const isScrolling = scrollTop >= 100;
+          resultsElement.classList.toggle("scrolling", isScrolling);
+        }
+      },
+      true
+    );
+  },
+  { on: [searxng.endpoint === "results"] }
+);