/* Copyright 2018 Google LLC Use of this source code is governed by an MIT-style license that can be found in the LICENSE file or at https://opensource.org/licenses/MIT. */ import {errors} from './errors'; import {escapeRegExp} from './escape-regexp'; import {ManifestTransform} from '../types'; export function modifyURLPrefixTransform(modifyURLPrefix: { [key: string]: string; }): ManifestTransform { if ( !modifyURLPrefix || typeof modifyURLPrefix !== 'object' || Array.isArray(modifyURLPrefix) ) { throw new Error(errors['modify-url-prefix-bad-prefixes']); } // If there are no entries in modifyURLPrefix, just return an identity // function as a shortcut. if (Object.keys(modifyURLPrefix).length === 0) { return (manifest) => { return {manifest}; }; } for (const key of Object.keys(modifyURLPrefix)) { if (typeof modifyURLPrefix[key] !== 'string') { throw new Error(errors['modify-url-prefix-bad-prefixes']); } } // Escape the user input so it's safe to use in a regex. const safeModifyURLPrefixes = Object.keys(modifyURLPrefix).map(escapeRegExp); // Join all the `modifyURLPrefix` keys so a single regex can be used. const prefixMatchesStrings = safeModifyURLPrefixes.join('|'); // Add `^` to the front the prefix matches so it only matches the start of // a string. const modifyRegex = new RegExp(`^(${prefixMatchesStrings})`); return (originalManifest) => { const manifest = originalManifest.map((entry) => { if (typeof entry.url !== 'string') { throw new Error(errors['manifest-entry-bad-url']); } entry.url = entry.url.replace(modifyRegex, (match) => { return modifyURLPrefix[match]; }); return entry; }); return {manifest}; }; }