scripts/build/generate_css_js_files.js

// Copyright 2021 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
const cssnano = require('cssnano');
const cssnanoPresetLite = require('cssnano-preset-lite');
const fs = require('fs');
const path = require('path');
const postcss = require('postcss');

const {writeIfChanged} = require('./ninja/write-if-changed.js');

async function runCSSMinification(input, fileName) {
  // postcss needs to be given a fileName, even though it doesn't read from it nor write to it.
  // So we pass in the correct name, even though it has no impact on the resulting code.
  const result = await postcss([
                   cssnano({preset: cssnanoPresetLite}),
                 ]).process(input, {from: fileName});
  return result.css;
}

async function codeForFile({fileName, input, isDebug, buildTimestamp}) {
  input = input.replace(/\`/g, '\\\'');
  input = input.replace(/\\/g, '\\\\');

  const stylesheetContents = isDebug ? input : await runCSSMinification(input, fileName);

  const year = new Date(Number(buildTimestamp) * 1000).getUTCFullYear();
  return `// Copyright ${year} The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
// IMPORTANT: this file is auto generated. Please do not edit this file.
/* istanbul ignore file */
export default \`${stylesheetContents}
/*# sourceURL=\${import.meta.resolve('./${fileName}')} */\`;`;
}

// Exported only so it can be unit tested.
exports.codeForFile = codeForFile;

async function runMain() {
  const [, , buildTimestamp, isDebugString, targetName, srcDir, targetGenDir, files, ] = process.argv;

  const filenames = files.split(',');
  const configFiles = [];
  const isDebug = isDebugString === 'true';

  for (const fileName of filenames) {
    const contents = fs.readFileSync(path.join(srcDir, fileName), {
      encoding: 'utf8',
      flag: 'r',
    });
    const newContents = await codeForFile({
      fileName,
      isDebug,
      input: contents,
      buildTimestamp,
    });
    const generatedFileName = `${fileName}.js`;
    const generatedFileLocation = path.join(targetGenDir, generatedFileName);

    writeIfChanged(generatedFileLocation, newContents);

    configFiles.push(`\"${generatedFileName}\"`);
  }

  writeIfChanged(
      path.join(targetGenDir, `${targetName}-tsconfig.json`),
      `{
    "compilerOptions": {
        "composite": true,
        "outDir": "."
    },
    "files": [
        ${configFiles.join(',\n        ')}
    ]
}
`,
  );
}

if (require.main === module) {
  runMain();
}