import type { Hono } from "hono";
import type { Bucket } from "../bucket/reader.ts";
import { headId, saveByPrefix } from "../mirror/queries.ts";
import { notFound, openPublicRepo, type PageContext } from "../pages/layout.ts";
import { countInstall } from "../releases/releases.ts";
import { cachedTarball } from "./cache.ts";

// Long-lived but never `immutable` (§18): a strip can change what a save's tarball holds. `private`,
// so no shared cache keeps it after the repo turns private (§20).
const TARBALL_CACHE = "private, max-age=31536000";

export function registerTarballRoutes(app: Hono, ctx: PageContext, bucket: Bucket): void {
	app.get("/:repo/archive/HEAD.tar.gz", (c) => {
		const repo = openPublicRepo(ctx, c.req.param("repo"));
		const head = repo && headId(repo.mirror);
		if (!repo || !head) return notFound(c, ctx);
		const path = `/${repo.settings.name}/archive/${head}.tar.gz`;
		// Nix pins the immutable link in its lock file, so it must be absolute.
		c.header("Link", `<https://${ctx.domain}${path}>; rel="immutable"`);
		c.header("Cache-Control", "no-cache");
		return c.redirect(path, 302);
	});

	app.get("/:repo/archive/:id{[0-9a-f]+\\.tar\\.gz}", async (c) => {
		const repo = openPublicRepo(ctx, c.req.param("repo"));
		const id = c.req.param("id").replace(/\.tar\.gz$/, "");
		const save = repo && saveByPrefix(repo.mirror, id);
		if (!repo || !save) return notFound(c, ctx);
		const name = repo.settings.name;
		if (save.id !== id) {
			c.header("Cache-Control", "public, max-age=60");
			return c.redirect(`/${name}/archive/${save.id}.tar.gz`, 302);
		}
		const bytes = await cachedTarball(bucket, repo.mirror, name, save.id);
		if (!bytes) return notFound(c, ctx);
		// §22.2: a Nix fetch is an install. Only the tarball itself counts, not the redirects to it.
		if (c.req.header("User-Agent")?.includes("nix/")) countInstall(ctx.kepr, name);
		c.header("Content-Type", "application/gzip");
		c.header("Content-Disposition", `attachment; filename="${name}-${save.id.slice(0, 8)}.tar.gz"`);
		c.header("Cache-Control", TARBALL_CACHE);
		return c.body(bytes.slice());
	});
}