feat: refactored docs structure

apps/docs/components/ProblemBadges.astro

@@ -0,0 +1,134 @@
+---
+/**
+ * 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 card on the
+ *   Appendix glossary, `/appendix#<slug>` (`appendix.ts`), and is outlined.
+ *   `tagTarget()` picks the route (and between two landings, e.g. DFS); the
+ *   `PageFooter` backlinks list and the Appendix page read the same answer.
+ *   Each tag badge is a pill carrying the icon its target shows (a topic's
+ *   `meta.ts` icon in the sidebar, a term's `icon` on its card) and the tag's
+ *   own colour (`lib/tag-colors.ts`), assigned over every tag the site has a
+ *   page or card for — no two tags share one, and tags that share problem
+ *   pages are spread furthest apart. A tag with neither (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.
+ * - `issue:` (problem pages, written by sync) is the problem's GitHub issue
+ *   URL, a neutral "Issue #N" badge with the GitHub mark, right after
+ *   "Explanation" at the end of the row.
+ */
+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 { APPENDIX } from "../appendix.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 issue: string | undefined = entry?.data.issue;
+
+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 landing or an Appendix card, coloured against how problem
+// pages (`<num>. <name>` titles, the shape sync writes) combine them. Only a
+// page with tags needs the answer.
+const colors = tags.length
+  ? tagColors(
+      [...Object.keys(TOPIC_LANDINGS), ...Object.keys(APPENDIX)],
+      await Promise.all(
+        data.routes
+          .filter((r: { title: string }) => /^\d+\.\s/u.test(r.title))
+          .map(async (r: { collection: string; entryId: string }) => {
+            const page = await getEntry(r.collection, r.entryId);
+            return (page?.data.topics ?? []).map((t: TopicTag) => t.slug);
+          }),
+      ),
+    )
+  : new Map<string, string>();
+
+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: target.kind === "appendix" ? APPENDIX[tag.slug]?.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 || issue) && (
+    <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>
+      )}
+      {issue && (
+        <a href={issue} target="_blank" rel="noopener" class={linkClass}>
+          <Badge icon="github" shape="pill">
+            Issue #{issue.slice(issue.lastIndexOf("/") + 1)}
+          </Badge>
+        </a>
+      )}
+    </div>
+  )
+}
+
+<slot />