leetcode/apps/docs/components/ProblemBadges.astro

---
/**
 * The MDX `wrapper`: the badge row between a page's description and its body.
 * Blume's page template renders the title and description itself and then
 * the MDX content, with no slot in between, so wrapping the content is the
 * only way to land right after the description. MDX hands a wrapper no
 * route, so it is read off the URL, and the page's frontmatter is then
 * looked up through the route manifest — the same `getEntry` call Blume's own
 * page template makes. Pages with none of the keys below (landing pages, the
 * changelog) render only their content.
 *
 * - `topics:` (problem pages, written by `apps/cli/sync.ts`) is LeetCode's own
 *   topic tags. A tag the campaign teaches (`topic-landings.ts`) links to that
 *   topic's landing page and is filled; any other tag links to its guide
 *   page, `/guides/<slug>` (sync creates one per such tag), and is outlined.
 *   `tagTarget()` picks the route (and between two landings, e.g. DFS); the
 *   `PageFooter` backlinks list reads the same answer. Each tag badge is a
 *   pill carrying the icon its target shows in the sidebar (the topic's
 *   `meta.ts` icon, the guide's `icon:`) and the tag's own colour
 *   (`lib/tag-colors.ts`), assigned over every tag the site has a page for,
 *   so no two tags share one. A tag with no page (the LeetCode-list fallback)
 *   stays gray and iconless.
 * - `video:` (problem pages, written by `apps/cli/videos.ts`) is the NeetCode
 *   walkthrough's YouTube id, the red "Explanation" badge at the end of the row.
 * - `list:` (guide pages, written by sync on create) is the tag's LeetCode
 *   problem list, an orange "LeetCode list" badge.
 */
import { getEntry } from "astro:content";
import data from "blume:data";
import Badge from "blume/components/content/Badge.astro";
import { stripBase, withBase } from "blume/components/islands/base-path.ts";
import { tagColors } from "../lib/tag-colors.ts";
import { TOPIC_LANDINGS, tagTarget, type TopicTag } from "../topic-landings.ts";

// `/sub/tree-dfs/invert-binary-tree/` (or `.../index.html` in a static build)
// -> `/tree-dfs/invert-binary-tree`, the base-less shape of `data.routes`.
const route =
  stripBase(import.meta.env.BASE_URL ?? "/", Astro.url.pathname)
    .replace(/(\/index)?\.html$/u, "")
    .replace(/(.)\/+$/u, "$1");
const at = data.routes.find((r: { path: string }) => r.path === route);
const entry = at ? await getEntry(at.collection, at.entryId) : undefined;
const tags: TopicTag[] = entry?.data.topics ?? [];
const video: string | undefined = entry?.data.video;
const list: string | undefined = entry?.data.list;

const served = new Set<string>(data.routes.map((r: { path: string }) => r.path));

// route → the icon its sidebar row shows: a page's own, or a topic group's
// (from its `meta.ts`) for the landing page the group row links to.
interface NavNode {
  route?: string;
  icon?: string;
  children?: NavNode[];
}
const icons = new Map<string, string>();
const walk = (nodes: NavNode[]) => {
  for (const node of nodes) {
    if (node.route && node.icon && !icons.has(node.route)) icons.set(node.route, node.icon);
    if (node.children) walk(node.children);
  }
};
walk(data.navigation.sidebar);

// Every tag with a page: the ones a landing teaches, plus every served guide.
const colors = tagColors([
  ...Object.keys(TOPIC_LANDINGS),
  ...[...served].flatMap((path) => path.match(/^\/guides\/([^/]+)$/u)?.slice(1) ?? []),
]);

const badges = tags.map((tag) => {
  const target = tagTarget(tag, { route, tags }, served);
  const external = target.kind === "external";
  return {
    name: tag.name,
    href: external ? target.href : withBase(target.href),
    external,
    icon: external ? undefined : icons.get(target.href),
    color: external ? undefined : colors.get(tag.slug),
    stroke: target.kind !== "landing",
  };
});

const linkClass = "no-underline transition-opacity hover:opacity-80";
---

{
  (badges.length > 0 || video || list) && (
    <div class="not-prose mb-6 flex flex-wrap gap-1.5">
      {badges.map((b) => (
        <a
          href={b.href}
          target={b.external ? "_blank" : undefined}
          rel={b.external ? "noopener" : undefined}
          class={linkClass}
        >
          <Badge color={b.color} icon={b.icon} shape="pill" stroke={b.stroke}>
            {b.name}
          </Badge>
        </a>
      ))}
      {video && (
        <a href={`https://www.youtube.com/watch?v=${video}`} target="_blank" rel="noopener" class={linkClass}>
          <Badge variant="danger" icon="youtube" shape="pill">
            Explanation
          </Badge>
        </a>
      )}
      {list && (
        <a href={list} target="_blank" rel="noopener" class={linkClass}>
          <Badge variant="warning" icon="list" shape="pill">
            LeetCode list
          </Badge>
        </a>
      )}
    </div>
  )
}

<slot />