Source: webCache/RemoteWebCache.js

const fetch = require('node-fetch');
const { WebCache, VersionResolveError } = require('./WebCache');
const { verifyWebCacheIntegrity } = require('./WebCacheIntegrity');

/**
 * RemoteWebCache - Fetches a WhatsApp Web version index from a remote server
 * @param {object} options - options
 * @param {string} options.remotePath - Endpoint that should be used to fetch the version index. Use {version} as a placeholder for the version number.
 * @param {boolean} options.strict - If true, will throw an error if the requested version can't be fetched. Defaults to true.
 * @param {Record<string, {sha256: string, sizeBytes: number}>} options.integrity - Optional immutable artifact manifest.
 */
class RemoteWebCache extends WebCache {
    constructor(options = {}) {
        super();

        if (!options.remotePath)
            throw new Error(
                'webVersionCache.remotePath is required when using the remote cache',
            );
        this.remotePath = options.remotePath;
        this.strict = options.strict !== false;
        this.integrity = options.integrity;
    }

    async resolve(version) {
        const remotePath = this.remotePath.replace('{version}', version);

        try {
            const cachedRes = await fetch(remotePath);
            if (cachedRes.ok) {
                const content = await cachedRes.text();
                return verifyWebCacheIntegrity(
                    content,
                    version,
                    this.integrity,
                );
            }
        } catch (err) {
            // An integrity manifest is a pin, not a best-effort cache hint.
            // Never turn a mismatched remote artifact into a live-Web fallback
            // when strict mode is disabled.
            if (err instanceof VersionResolveError) throw err;
            console.error(`Error fetching version ${version} from remote`, err);
        }

        if (this.strict)
            throw new VersionResolveError(
                `Couldn't load version ${version} from the archive`,
            );
        return null;
    }

    async persist() {
        // Nothing to do here
    }
}

module.exports = RemoteWebCache;