chore: website tooling (#41)

website/src/utils/globWithParser.ts

@@ -0,0 +1,81 @@
+import { glob, type ParseDataOptions } from 'astro/loaders';
+
+/**
+ * Parser function that runs before Astro's schema validation.
+ * Receives the entry and the original filename (before generateId transforms it).
+ */
+type Parser = <TData extends Record<string, unknown>>(
+	options: ParseDataOptions<TData>,
+	originalEntry: string,
+) => Promise<ParseDataOptions<TData>>;
+
+type GlobWithParserOptions = Parameters<typeof glob>[0] & {
+	parser: Parser;
+};
+
+/**
+ * Wraps Astro's glob loader to provide a parser function that has access to both
+ * the transformed entry and the original filename.
+ *
+ * This is useful when using generateId to transform entry IDs (e.g., for clean URLs)
+ * but still needing the original filename to extract metadata (e.g., dates from filenames).
+ *
+ * @example
+ * ```ts
+ * loader: globWithParser({
+ *   base: './src/content/blog',
+ *   pattern: '**\/*.md',
+ *   generateId: ({ entry }) => entry.replace(/^\d{4}-\d{2}-\d{2}-/, ''),
+ *   parser: async (entry, originalEntry) => {
+ *     // entry.id = "my-post", originalEntry = "2024-01-01-my-post.md"
+ *     const date = extractDateFromFilename(originalEntry);
+ *     entry.data.pubDate = date;
+ *     return entry;
+ *   }
+ * })
+ * ```
+ */
+export function globWithParser({
+	parser,
+	generateId,
+	...globOptions
+}: GlobWithParserOptions) {
+	/**
+	 * Store mapping of transformed IDs to original entry filenames.
+	 * Created per-invocation to avoid memory leaks across builds.
+	 * This is needed because generateId transforms the entry name (e.g., removes date prefix),
+	 * but we need access to the original filename in the parser (e.g., to extract date from filename).
+	 */
+	const entryMap = new Map<string, string>();
+
+	// Wrap generateId to capture the original entry name before transformation
+	// This allows us to maintain a mapping from the transformed ID back to the original filename
+	const wrappedGenerateId = generateId
+		? (ctx: Parameters<NonNullable<typeof generateId>>[0]) => {
+				const newId = generateId(ctx);
+				// Store mapping: transformed ID -> original filename
+				entryMap.set(newId, ctx.entry);
+				return newId;
+			}
+		: undefined;
+
+	// Create the base glob loader with our wrapped generateId
+	const loader = glob({ ...globOptions, generateId: wrappedGenerateId });
+	const originalLoad = loader.load;
+
+	// Intercept the load function to inject our custom parser
+	// This allows us to provide both the transformed entry and original filename to the parser
+	loader.load = async ({ parseData, ...rest }) => {
+		return originalLoad({
+			parseData: async (entry) => {
+				// Retrieve the original filename from our map, falling back to entry.id if not found
+				const originalEntry = entryMap.get(entry.id) || entry.id;
+				// Call user's parser with both the transformed entry and original filename
+				return parseData(await parser(entry, originalEntry));
+			},
+			...rest,
+		});
+	};
+
+	return loader;
+}