v6 / lib / events.js

import { execSync } from 'node:child_process';
import { existsSync, mkdirSync } from "node:fs";
import { join } from "node:path";
import sharp from "sharp";

export function setupEvents(eleventyConfig) {
	let blogPosts = [];

	eleventyConfig.addCollection("posts", (collectionApi) => {
		const posts = collectionApi.getFilteredByTag("post");
		blogPosts = posts;
		return posts;
	});

	eleventyConfig.on("eleventy.after", async () => {
		mkdirSync("_site/og", { recursive: true });

		for (const post of blogPosts) {
			const { data, page } = post;

			const title = data?.title ?? "Untitled";
			const subtitle = data?.description ?? data?.subtitle ?? "";
			const datestring = data?.date
				? new Date(data.date).toLocaleDateString("en-GB", {
						year: "numeric",
						month: "long",
						day: "numeric",
					})
				: "";

			const slug = page.url.replace(/^\/|\/$/g, "").replace(/\//g, "-") || "index";
			const outPath = join("_site/og", `${slug}.jpg`);

			if (existsSync(outPath)) {
				console.log(`[og] Skipping ${outPath} (already exists)`);
				continue;
			}

			try {
				const png = execSync(
					[
						`typst compile ./typst/og_image.typ`,
						`--font-path ./typst/`,
						`--input title=${JSON.stringify(title)}`,
						`--input subtitle=${JSON.stringify(subtitle)}`,
						`--input datestring=${JSON.stringify(datestring)}`,
						`--format png -`,
					].join(" "),
					{ maxBuffer: 10 * 1024 * 1024 }
				);

				await sharp(png)
					.jpeg({ quality: 85, mozjpeg: true })
					.toFile(outPath);

				console.log(`[og] Generated ${outPath}`);
			} catch (err) {
				console.error(`[og] Failed for ${page.url}:`, err.message);
			}
		}
	});
}