Add Goodreads series and group them on the about page

src/lib/books/series.ts

@@ -0,0 +1,60 @@
+import type { Book, BookShelf } from '#lib/content';
+
+export interface BookSeriesGroup {
+	name: string;
+	url: string;
+	books: Book[];
+	counts: Record<BookShelf, number>;
+}
+
+export interface GroupedBooks {
+	series: BookSeriesGroup[];
+	standalone: Book[];
+}
+
+const positionGroups = { single: 0, range: 1, none: 2 };
+
+function seriesOrder(first: Book, second: Book): number {
+	const [firstGroup, firstNumber] = positionKey(first);
+	const [secondGroup, secondNumber] = positionKey(second);
+	return firstGroup - secondGroup || firstNumber - secondNumber;
+}
+
+function positionKey(book: Book): [number, number] {
+	const position = book.series?.position ?? '';
+	const match = position.match(/\d+(?:\.\d+)?/);
+	if (!match) return [positionGroups.none, 0];
+	const isRange = /\d\s*[-–]\s*\d/.test(position);
+	return [isRange ? positionGroups.range : positionGroups.single, Number(match[0])];
+}
+
+function shelfCounts(books: Book[]): Record<BookShelf, number> {
+	return {
+		read: books.filter((book) => book.shelf === 'read').length,
+		reading: books.filter((book) => book.shelf === 'reading').length,
+		'want-to-read': books.filter((book) => book.shelf === 'want-to-read').length
+	};
+}
+
+export function groupBySeries(books: Book[]): GroupedBooks {
+	const groups = new Map<string, Book[]>();
+	const standalone: Book[] = [];
+
+	for (const book of books) {
+		if (!book.series) {
+			standalone.push(book);
+			continue;
+		}
+		const key = book.series.url || book.series.name;
+		groups.set(key, [...(groups.get(key) ?? []), book]);
+	}
+
+	const series = [...groups.values()]
+		.map((seriesBooks) => {
+			const ordered = [...seriesBooks].sort(seriesOrder);
+			return { name: ordered[0].series!.name, url: ordered[0].series!.url, books: ordered, counts: shelfCounts(ordered) };
+		})
+		.sort((first, second) => second.counts.read - first.counts.read || first.name.localeCompare(second.name));
+
+	return { series, standalone };
+}