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/*
Author Ivan Kopeykin @vankop
*/
"use strict";
/** @typedef {import("./Hash")} Hash */
const A_CODE = "a".charCodeAt(0);
/**
* Returns hash that has at least one non numeric char.
* @param {string} hash hash
* @param {number} hashLength hash length
* @returns {string} returns hash that has at least one non numeric char
*/
const nonNumericOnlyHash = (hash, hashLength) => {
if (hashLength < 1) return "";
const slice = hash.slice(0, hashLength);
if (/[^\d]/.test(slice)) return slice;
return `${String.fromCharCode(
A_CODE + (Number.parseInt(hash[0], 10) % 6)
)}${slice.slice(1)}`;
};
/**
* Digests a hash and truncates it to a content-hash string (non-numeric first char).
* @param {Hash} hash hash
* @param {string} hashDigest digest encoding
* @param {number} hashDigestLength hash length
* @returns {string} content hash string
*/
const digestNonNumericOnly = (hash, hashDigest, hashDigestLength) =>
nonNumericOnlyHash(hash.digest(hashDigest), hashDigestLength);
/**
* Digests a hash, returning both the truncated content-hash string and the full
* (untruncated) digest, so `[contenthash:<digest>]` can re-encode from full entropy.
* @param {Hash} hash hash
* @param {string} hashDigest digest encoding
* @param {number} hashDigestLength hash length
* @returns {[string, string]} content hash string and full digest
*/
const digestNonNumericOnlyWithFull = (hash, hashDigest, hashDigestLength) => {
const full = /** @type {string} */ (hash.digest(hashDigest));
return [nonNumericOnlyHash(full, hashDigestLength), full];
};
module.exports = nonNumericOnlyHash;
module.exports.digestNonNumericOnly = digestNonNumericOnly;
module.exports.digestNonNumericOnlyWithFull = digestNonNumericOnlyWithFull;