/*
  Copyright 2019 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 {rollup} = require('rollup');
const {terser} = require('rollup-plugin-terser');
const {writeFile} = require('fs-extra');
const babel = require('rollup-plugin-babel');
const omt = require('@surma/rollup-plugin-off-main-thread');
const upath = require('upath');
const presetEnv = require('@babel/preset-env');
const replace = require('@rollup/plugin-replace');
const resolve = require('@rollup/plugin-node-resolve');
const tempy = require('tempy');

module.exports = async ({
  babelPresetEnvTargets,
  inlineWorkboxRuntime,
  mode,
  sourcemap,
  swDest,
  unbundledCode,
}) => {
  // We need to write this to the "real" file system, as Rollup won't read from
  // a custom file system.
  const {dir, base} = upath.parse(swDest);

  const temporaryFile = tempy.file({name: base});
  await writeFile(temporaryFile, unbundledCode);

  const plugins = [
    resolve(),
    replace({'process.env.NODE_ENV': JSON.stringify(mode)}),
    babel({
      // Disable the logic that checks for local Babel config files:
      // https://github.com/GoogleChrome/workbox/issues/2111
      babelrc: false,
      configFile: false,
      presets: [[presetEnv, {
        targets: {
          browsers: babelPresetEnvTargets,
        },
        loose: true,
      }]],
    }),
  ];

  if (mode === 'production') {
    plugins.push(terser({
      mangle: {
        toplevel: true,
        properties: {
          regex: /(^_|_$)/,
        },
      },
    }));
  }

  const rollupConfig = {
    plugins,
    input: temporaryFile,
  };

  // Rollup will inline the runtime by default. If we don't want that, we need
  // to add in some additional config.
  if (!inlineWorkboxRuntime) {
    rollupConfig.plugins.unshift(omt());
    rollupConfig.manualChunks = (id) => {
      return id.includes('workbox') ? 'workbox' : undefined;
    };
  }

  const bundle = await rollup(rollupConfig);

  const {output} = await bundle.generate({
    sourcemap,
    // Using an external Workbox runtime requires 'amd'.
    format: inlineWorkboxRuntime ? 'es' : 'amd',
  });

  const files = [];
  for (const chunkOrAsset of output) {
    if (chunkOrAsset.isAsset) {
      files.push({
        name: chunkOrAsset.fileName,
        contents: chunkOrAsset.source,
      });
    } else {
      let code = chunkOrAsset.code;

      if (chunkOrAsset.map) {
        const sourceMapFile = chunkOrAsset.fileName + '.map';
        code += `//# sourceMappingURL=${sourceMapFile}\n`;

        files.push({
          name: sourceMapFile,
          contents: chunkOrAsset.map.toString(),
        });
      }

      files.push({
        name: chunkOrAsset.fileName,
        contents: code,
      });
    }
  }

  // Make sure that if there was a directory portion included in swDest, it's
  // preprended to all of the generated files.
  return files.map((file) => {
    file.name = upath.format({
      dir,
      base: file.name,
    });
    return file;
  });
};