/**
 * A bucket in memory, served over HTTP for the joint public-steal test: koh's own S3 backend and
 * Bun's S3Client both talk to it, so Kepr and the two koh machines share one bucket.
 *
 * It runs as its own process because the test drives koh with `Bun.spawnSync`, which would block
 * the event loop this server needs. It prints its endpoint on the first line of stdout.
 *
 * Only what the two clients use is implemented: GET, HEAD, PUT (with `If-None-Match: *` for the
 * one conditional write that matters, `head`), DELETE, and ListObjectsV2. Signatures are ignored
 * rather than verified — the one way this is easier than a real bucket.
 */
const BUCKET = "kohbucket";
const objects = new Map<string, Uint8Array>();

async function handle(request: Request): Promise<Response> {
	const url = new URL(request.url);
	const [, bucket = "", ...rest] = url.pathname.split("/");
	if (bucket !== BUCKET) return new Response("", { status: 404 });
	if (url.searchParams.get("list-type") === "2") {
		const prefix = url.searchParams.get("prefix") ?? "";
		const delimiter = url.searchParams.get("delimiter");
		const keys = [...objects.keys()].filter((key) => key.startsWith(prefix)).sort();
		// With a delimiter, keys sharing a folder after the prefix roll up into one CommonPrefixes.
		const folders = new Set<string>();
		const listed = keys.filter((key) => {
			const at = delimiter ? key.indexOf(delimiter, prefix.length) : -1;
			if (at >= 0) folders.add(key.slice(0, at + 1));
			return at < 0;
		});
		const contents = listed
			.map(
				(key) =>
					`<Contents><Key>${key}</Key><Size>${objects.get(key)?.length ?? 0}</Size></Contents>`,
			)
			.join("");
		const common = [...folders]
			.map((folder) => `<CommonPrefixes><Prefix>${folder}</Prefix></CommonPrefixes>`)
			.join("");
		return new Response(
			`<?xml version="1.0" encoding="UTF-8"?><ListBucketResult><IsTruncated>false</IsTruncated>${contents}${common}</ListBucketResult>`,
			{ headers: { "content-type": "application/xml" } },
		);
	}
	const key = rest.join("/");
	if (request.method === "PUT") {
		const body = new Uint8Array(await request.arrayBuffer());
		if (request.headers.get("if-none-match") === "*" && objects.has(key)) {
			return new Response("", { status: 412 });
		}
		objects.set(key, body);
		return new Response("", { status: 200, headers: { etag: `"${body.length}"` } });
	}
	if (request.method === "GET" || request.method === "HEAD") {
		const body = objects.get(key);
		if (!body) return new Response("", { status: 404 });
		return new Response(request.method === "HEAD" ? null : body, {
			status: 200,
			headers: { etag: `"${body.length}"`, "content-length": String(body.length) },
		});
	}
	if (request.method === "DELETE") {
		objects.delete(key);
		return new Response("", { status: 204 });
	}
	return new Response("", { status: 404 });
}

const server = Bun.serve({ port: 0, fetch: handle });
console.log(`http://127.0.0.1:${server.port}`);