workbox-build/src/lib/filter-files.js

/*
  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.
*/

const maximumSizeTransform = require('./maximum-size-transform');
const modifyURLPrefixTranform = require('./modify-url-prefix-transform');
const noRevisionForURLsMatchingTransform =
  require('./no-revision-for-urls-matching-transform');

/**
 * A `ManifestTransform` function can be used to modify the modify the `url` or
 * `revision` properties of some or all of the
 * {@link module:workbox-build#ManifestEntry|ManifestEntries} in the manifest.
 *
 * Deleting the `revision` property of an entry will cause
 * the corresponding `url` to be precached without cache-busting parameters
 * applied, which is to say, it implies that the URL itself contains
 * proper versioning info. If the `revision` property is present, it must be
 * set to a string.
 *
 * @example <caption>A transformation that prepended the origin of a CDN for any
 * URL starting with '/assets/' could be implemented as:</caption>
 *
 * const cdnTransform = (manifestEntries) => {
 *   const manifest = manifestEntries.map(entry => {
 *     const cdnOrigin = 'https://example.com';
 *     if (entry.url.startsWith('/assets/')) {
 *       entry.url = cdnOrigin + entry.url;
 *     }
 *     return entry;
 *   });
 *   return {manifest, warnings: []};
 * };
 *
 * @example <caption>A transformation that removes the revision field when the
 * URL contains an 8-character hash surrounded by '.', indicating that it
 * already contains revision information:</caption>
 *
 * const removeRevisionTransform = (manifestEntries) => {
 *   const manifest = manifestEntries.map(entry => {
 *     const hashRegExp = /\.\w{8}\./;
 *     if (entry.url.match(hashRegExp)) {
 *       delete entry.revision;
 *     }
 *     return entry;
 *   });
 *   return {manifest, warnings: []};
 * };
 *
 * @callback ManifestTransform
 * @param {Array<module:workbox-build.ManifestEntry>} manifestEntries The full
 * array of entries, prior to the current transformation.
 * @return {module:workbox-build.ManifestTransformResult}
 * The array of entries with the transformation applied, and optionally, any
 * warnings that should be reported back to the build tool.
 *
 * @memberof module:workbox-build
 */

module.exports = ({
  dontCacheBustURLsMatching,
  fileDetails,
  manifestTransforms,
  maximumFileSizeToCacheInBytes,
  modifyURLPrefix,
}) => {
  let allWarnings = [];

  // Take the array of fileDetail objects and convert it into an array of
  // {url, revision, size} objects, with \ replaced with /.
  const normalizedManifest = fileDetails.map((fileDetails) => {
    return {
      url: fileDetails.file.replace(/\\/g, '/'),
      revision: fileDetails.hash,
      size: fileDetails.size,
    };
  });

  let transformsToApply = [];

  if (maximumFileSizeToCacheInBytes) {
    transformsToApply.push(maximumSizeTransform(maximumFileSizeToCacheInBytes));
  }

  if (modifyURLPrefix) {
    transformsToApply.push(modifyURLPrefixTranform(modifyURLPrefix));
  }

  if (dontCacheBustURLsMatching) {
    transformsToApply.push(
        noRevisionForURLsMatchingTransform(dontCacheBustURLsMatching));
  }

  // Any additional manifestTransforms that were passed will be applied last.
  transformsToApply = transformsToApply.concat(manifestTransforms || []);

  let transformedManifest = normalizedManifest;
  for (const transform of transformsToApply) {
    const {manifest, warnings} = transform(transformedManifest);
    transformedManifest = manifest;
    allWarnings = allWarnings.concat(warnings || []);
  }

  // Generate some metadata about the manifest before we clear out the size
  // properties from each entry.
  const count = transformedManifest.length;
  let size = 0;
  for (const manifestEntry of transformedManifest) {
    size += manifestEntry.size;
    delete manifestEntry.size;
  }

  return {
    count,
    size,
    manifestEntries: transformedManifest,
    warnings: allWarnings,
  };
};