microsite/utils/prefetch.js

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var __rest = (this && this.__rest) || function (s, e) {
    var t = {};
    for (var p in s) if (Object.prototype.hasOwnProperty.call(s, p) && e.indexOf(p) < 0)
        t[p] = s[p];
    if (s != null && typeof Object.getOwnPropertySymbols === "function")
        for (var i = 0, p = Object.getOwnPropertySymbols(s); i < p.length; i++) {
            if (e.indexOf(p[i]) < 0 && Object.prototype.propertyIsEnumerable.call(s, p[i]))
                t[p[i]] = s[p[i]];
        }
    return t;
};
import fetch, { Request } from "node-fetch";
import CachePolicy from "http-cache-semantics";
import { promises as fsp } from "fs";
import { join } from "path";
import { createHash } from "crypto";
export function createPrefetch(previousKey) {
    return async function prefetch(info, init = {}) {
        // file mode
        if (typeof info === "string" && !info.startsWith("http")) {
            const key = await createFileKey(info);
            return Buffer.from(JSON.stringify({ type: "fs", key })).toString("base64");
        }
        // fetch mode
        let req = new Request(info, Object.assign(Object.assign({}, init), { method: "HEAD" }));
        let previousPolicy = null;
        let previousRes = null;
        if (previousKey) {
            const { policy, response } = JSON.parse(Buffer.from(previousKey, "base64").toString("utf8"));
            previousPolicy = CachePolicy.fromObject(policy);
            previousRes = response;
        }
        if (previousPolicy && previousPolicy.satisfiesWithoutRevalidation(req)) {
            previousRes.headers = previousPolicy.responseHeaders();
            const response = !previousPolicy.storable()
                ? null
                : serializeRes(previousRes);
            return Buffer.from(JSON.stringify({
                type: "network",
                policy: previousPolicy.toObject(),
                response,
            })).toString("base64");
        }
        if (previousPolicy) {
            req = new Request(info, Object.assign(Object.assign({}, init), { method: "HEAD", headers: Object.assign(Object.assign({}, req.headers), previousPolicy.revalidationHeaders(serializeReq(req))) }));
            const res = await fetch(req);
            const { policy, modified } = previousPolicy.revalidatedPolicy(req, res);
            const response = !policy.storable() ? null : serializeRes(res);
            if (modified) {
                return Buffer.from(JSON.stringify({
                    type: "network",
                    policy: policy.toObject(),
                    response,
                })).toString("base64");
            }
            return Buffer.from(JSON.stringify({
                type: "network",
                policy: previousPolicy.toObject(),
                response,
            })).toString("base64");
        }
        const res = await fetch(req);
        const policy = createPolicy(req, res);
        const response = !policy.storable() ? null : serializeRes(res);
        return Buffer.from(JSON.stringify({ policy: policy.toObject(), response })).toString("base64");
    };
}
export const isKeyValid = (previousKey, key) => {
    if (!previousKey || !key)
        return false;
    const { type } = JSON.parse(Buffer.from(previousKey, "base64").toString("utf8"));
    if (type === "fs")
        return previousKey === key;
    const _a = JSON.parse(Buffer.from(key, "base64").toString("utf8")), { type: _type } = _a, current = __rest(_a, ["type"]);
    return current.response.status === 200 || current.response.status === 304;
};
const serializeReq = (req) => ({
    url: req.url,
    method: req.method,
    headers: iterableToObject(req.headers),
});
const serializeRes = (res) => ({
    status: res.status,
    headers: iterableToObject(res.headers),
});
const iterableToObject = (iter) => {
    if (typeof iter.keys !== "function")
        return iter;
    let obj = {};
    for (const key of iter.keys()) {
        obj[key] = iter.get(key);
    }
    return obj;
};
const createPolicy = (req, res) => new CachePolicy(serializeReq(req), serializeRes(res), { shared: false });
async function createFileKey(p) {
    const hash = createHash("sha1");
    const stat = await fsp.stat(p);
    if (stat.isDirectory()) {
        for (const ent of await addDir(p, { mode: "dir" })) {
            hash.update(ent);
        }
    }
    else {
        hash.update(await addFile(p, { mode: "file" }));
    }
    return hash.digest("base64");
}
const addDir = async (p, { mode }) => {
    const ents = await fsp.readdir(p, { withFileTypes: true });
    const results = await Promise.all(ents.map((ent) => ent.isDirectory()
        ? addDir(join(p, ent.name), { mode })
        : addFile(join(p, ent.name), { mode })));
    return [].concat(...results);
};
const addFile = async (p, { mode }) => {
    if (mode === "dir") {
        return p;
    }
    else if (mode === "file") {
        const content = await fsp.readFile(p);
        return content;
    }
};