import { mkdir, readFile, rename, writeFile } from "node:fs/promises";
import { existsSync } from "node:fs";
import { join } from "node:path";

export interface Cache {
	get(key: string): Promise<Uint8Array | undefined>;
	put(
		key: string,
		value: Uint8Array,
		options?: { ttl?: number },
	): Promise<void>;
	delete(key: string): Promise<void>;
}

export interface CloudflareCacheLike {
	match(request: Request): Promise<Response | undefined>;
	put(request: Request, response: Response): Promise<void>;
	delete(request: Request): Promise<boolean>;
}

function cacheKey(key: string): string {
	return encodeURIComponent(key);
}

export function filesystemCache(dir: string): Cache {
	return {
		async get(key) {
			const path = join(dir, cacheKey(key));
			if (!existsSync(path)) return undefined;
			return new Uint8Array(await readFile(path));
		},
		async put(key, value) {
			await mkdir(dir, { recursive: true });
			const path = join(dir, cacheKey(key));
			const staged = `${path}.next`;
			await writeFile(staged, value);
			await rename(staged, path);
		},
		async delete(key) {
			const path = join(dir, cacheKey(key));
			if (existsSync(path)) await rename(path, `${path}.deleted`);
		},
	};
}

export function cloudflareCache(
	cache: CloudflareCacheLike,
	origin = "https://muddle.cache",
): Cache {
	const request = (key: string) =>
		new Request(new URL(`/${encodeURIComponent(key)}`, origin).toString());
	return {
		async get(key) {
			const response = await cache.match(request(key));
			return response
				? new Uint8Array(await response.arrayBuffer())
				: undefined;
		},
		async put(key, value, options) {
			const headers = options?.ttl
				? { "cache-control": `max-age=${options.ttl}` }
				: undefined;
			await cache.put(request(key), new Response(value, { headers }));
		},
		async delete(key) {
			await cache.delete(request(key));
		},
	};
}