import type { Database } from "bun:sqlite";
import { mkdirSync, readFileSync, renameSync, rmSync, writeFileSync } from "node:fs";
import { join } from "node:path";
import { filesAt, objectBytes } from "../mirror/queries.ts";
import { buildTarball } from "./tar.ts";

/**
 * A save's tarball from `<tarballDir>/<repo>/<id>.tar.gz`, built there on first request. Built and
 * written in one synchronous run, so a strip landing mid-build can't leave a stale file behind.
 */
export function cachedTarball(
	tarballDir: string,
	db: Database,
	repo: string,
	saveId: string,
): Uint8Array<ArrayBuffer> {
	const path = join(tarballDir, repo, `${saveId}.tar.gz`);
	try {
		return readFileSync(path);
	} catch (error) {
		if ((error as NodeJS.ErrnoException).code !== "ENOENT") throw error;
	}
	const files = filesAt(db, saveId).map((file) => {
		const bytes = objectBytes(db, file.hash);
		if (!bytes) throw new Error(`${repo}: object ${file.hash} is missing from the mirror`);
		return { path: file.path, executable: file.executable, bytes };
	});
	const tarball = buildTarball(`${repo}-${saveId.slice(0, 8)}`, files);
	mkdirSync(join(tarballDir, repo), { recursive: true });
	writeFileSync(`${path}.tmp`, tarball);
	renameSync(`${path}.tmp`, path);
	return tarball;
}

/** Drops cached tarballs a strip event reaches: one save's, or every one of the repo's for a whole-history strip. */
export function dropTarballs(tarballDir: string, repo: string, saveId: string): void {
	const target =
		saveId === "" ? join(tarballDir, repo) : join(tarballDir, repo, `${saveId}.tar.gz`);
	rmSync(target, { recursive: true, force: true });
}