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import { join } from "https://deno.land/std@0.136.0/path/mod.ts";import { existsDir, existsFile } from "./fs.ts";import log from "./log.ts";import util from "./util.ts";
const memoryCache = new Map<string, [Uint8Array, { headers: Record<string, string> }]>();
/** fetch and cache remote contents */export default async function cache(  url: string,  options?: { forceRefresh?: boolean; retryTimes?: number; userAgent?: string },): Promise<Response> {  const { protocol, hostname, port, pathname, search } = new URL(url);  const isLocalhost = ["localhost", "0.0.0.0", "127.0.0.1"].includes(hostname);  const modulesCacheDir = Deno.env.get("MODULES_CACHE_DIR");  const hashname = isLocalhost ? "" : await util.computeHash("sha-256", pathname + search + (options?.userAgent || ""));
  let cacheDir = "";  let metaFilepath = "";  let contentFilepath = "";  if (modulesCacheDir) {    cacheDir = join(modulesCacheDir, util.trimSuffix(protocol, ":"), hostname + (port ? "_PORT" + port : ""));    contentFilepath = join(cacheDir, hashname);    metaFilepath = join(cacheDir, hashname + ".metadata.json");  }
  if (!options?.forceRefresh && !isLocalhost) {    if (modulesCacheDir) {      if (await existsFile(contentFilepath) && await existsFile(metaFilepath)) {        const [content, meta] = await Promise.all([          Deno.readFile(contentFilepath),          Deno.readTextFile(metaFilepath),        ]);        try {          const { headers = {} } = JSON.parse(meta);          return new Response(content, { headers: { ...headers, "cache-hit": "true" } });        } catch (_e) {          return new Response(content);        }      }    } else if (memoryCache.has(hashname)) {      const [content, { headers }] = memoryCache.get(hashname)!;      return new Response(content, { headers: { ...headers, "cache-hit": "true" } });    }  }
  const retryTimes = options?.retryTimes ?? 3;  let finalRes = new Response("Server Error", { status: 500 });  for (let i = 0; i < retryTimes; i++) {    if (i === 0) {      if (!isLocalhost) {        log.debug("Download", url);      }    } else {      log.warn(`Download ${url} failed, retrying...`);    }
    const res = await fetch(url, { headers: options?.userAgent ? { "User-Agent": options?.userAgent } : undefined });    if (res.status >= 500) {      finalRes = res;      continue;    }
    if (res.ok && !isLocalhost) {      const buffer = await res.arrayBuffer();      const content = new Uint8Array(buffer);      const headers: Record<string, string> = {};      res.headers.forEach((val, key) => {        headers[key] = val;      });      if (modulesCacheDir) {        if (!(await existsDir(cacheDir))) {          await Deno.mkdir(cacheDir, { recursive: true });        }        await Promise.all([          Deno.writeFile(contentFilepath, content),          Deno.writeTextFile(            metaFilepath,            JSON.stringify(              { headers, url, now: { secs_since_epoch: Math.round(Date.now() / 1000), nanos_since_epoch: 0 } },              undefined,              2,            ),          ),        ]);      } else {        memoryCache.set(hashname, [content, { headers }]);      }      return new Response(content, { headers: res.headers });    }
    return res;  }
  return finalRes;}