@reclaimprotocol/zk-symmetric-crypto/lib/file-fetch.js

JS Wrappers for Various ZK Snark Circuits

import { GIT_COMMIT_HASH } from "./config.js";
const DEFAULT_REMOTE_BASE_URL = `https://github.com/reclaimprotocol/zk-symmetric-crypto/raw/${GIT_COMMIT_HASH}/resources/`;
const DEFAULT_BASE_PATH = '../resources';
/**
 * Fetches ZK resources from a remote server.
 * Assumes the structure of the resources is:
 * BASE_URL/{engine}/{filename}
 *
 * By default, it uses the resources from a specific commit
 * of the `zk-symmetric-crypto` repository.
 */
export function makeRemoteFileFetch({ baseUrl = DEFAULT_REMOTE_BASE_URL, maxRetries = 3, logger } = {}) {
    return {
        async fetch(engine, filename) {
            const url = `${baseUrl}/${engine}/${filename}`;
            let lastError;
            for (let attempt = 1; attempt <= maxRetries; attempt++) {
                try {
                    const res = await fetch(url);
                    if (!res.ok) {
                        throw new Error(`${engine}-${filename} fetch failed with code: ${res.status}`);
                    }
                    const arr = await res.arrayBuffer();
                    return new Uint8Array(arr);
                }
                catch (err) {
                    logger?.warn({ err, attempt, engine, filename }, 'failed to fetch zk resource');
                    lastError = err;
                    if (attempt < maxRetries) {
                        // add some delay before retrying
                        await new Promise(resolve => setTimeout(resolve, 1000 * attempt));
                    }
                }
            }
            throw lastError || new Error(`Failed to fetch ${engine}-${filename} after ${maxRetries} attempts`);
        },
    };
}
/**
 * Fetches ZK resources from the local file system.
 * Assumes the structure of the resources is:
 * BASE_PATH/{engine}/{filename}
 */
export function makeLocalFileFetch({ basePath = DEFAULT_BASE_PATH } = {}) {
    return {
        async fetch(engine, filename) {
            const path = `${basePath}/${engine}/${filename}`;
            // import here to avoid loading fs in
            // a browser env
            const { readFile } = await import('fs/promises');
            const { join, dirname } = await import('path');
            const { fileURLToPath } = await import('url');
            // fileURLToPath handles the Windows file:///F:/... -> F:\... conversion;
            // stripping the `file://` prefix by hand leaves a leading slash that breaks fs ops.
            const __dirname = dirname(fileURLToPath(import.meta.url));
            const fullPath = join(__dirname, path);
            const buff = await readFile(fullPath);
            return buff;
        },
    };
}