refactor: renamed md to posts, and plaintext to files

www/src/lib/posts.ts

@@ -0,0 +1,42 @@
+import type { CollectionEntry } from 'astro:content';
+import { DEFAULT_CATEGORY } from './consts';
+import { sortEntries } from './format';
+
+export type Post = CollectionEntry<'posts'> & { body?: string };
+
+export function getSlug(postId: string): string {
+  const parts = postId.split('/');
+  return parts[parts.length - 1];
+}
+
+export function resolveRelatedPosts<T extends { id: string }>(
+  slugs: string[],
+  allPosts: T[],
+): T[] {
+  const bySlug = new Map(allPosts.map(p => [getSlug(p.id), p]));
+  return slugs.flatMap(s => bySlug.get(s) ?? []);
+}
+
+export function organizePostsByCategory(posts: Post[]): {
+  grouped: Record<string, Post[]>;
+  categories: string[];
+} {
+  const grouped = posts.reduce((acc, post) => {
+    const category = post.data.category ?? DEFAULT_CATEGORY;
+    if (!acc[category]) acc[category] = [];
+    acc[category].push(post);
+    return acc;
+  }, {} as Record<string, Post[]>);
+
+  const categories = Object.keys(grouped).sort((a, b) => {
+    if (a === DEFAULT_CATEGORY) return -1;
+    if (b === DEFAULT_CATEGORY) return 1;
+    return a.localeCompare(b);
+  });
+
+  for (const category of categories) {
+    grouped[category] = sortEntries(grouped[category], p => p.data);
+  }
+
+  return { grouped, categories };
+}