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