/* eslint-disable global-require, no-console */
/*
  A high level overview of our client-side JavaScript bundling strategy can be found here:
  https://github.com/bbc/simorgh/blob/latest/docs/JavaScript-Bundling-Strategy.md
 */

const fs = require('fs');
const crypto = require('crypto');
const CopyWebpackPlugin = require('copy-webpack-plugin');
const TerserPlugin = require('terser-webpack-plugin');
const LoadablePlugin = require('@loadable/webpack-plugin');
const webpack = require('webpack');
const dotenv = require('dotenv');
const DuplicatePackageCheckerPlugin = require('duplicate-package-checker-webpack-plugin');
const { getClientEnvVars } = require('./src/clientEnvVars');

const FRAMEWORK_BUNDLES = ['react', 'react-dom'];
const TOTAL_PAGE_TYPES = fs
  .readdirSync('./src/app/pages')
  .filter(file => file.match(/[A-Z].+?Page$/)).length;

const DOT_ENV_CONFIG = dotenv.config();

if (DOT_ENV_CONFIG.error) {
  throw DOT_ENV_CONFIG.error;
}

module.exports = ({
  resolvePath,
  IS_PROD,
  START_DEV_SERVER,
  IS_PROD_PROFILE,
  BUNDLE_TYPE,
}) => {
  const {
    SIMORGH_APP_ENV,
    SIMORGH_PUBLIC_STATIC_ASSETS_ORIGIN,
    SIMORGH_PUBLIC_STATIC_ASSETS_PATH,
  } = process.env;
  const APP_ENV = SIMORGH_APP_ENV || 'live';
  const IS_LEGACY_WEB = BUNDLE_TYPE === 'legacy';
  const webpackDevServerPort = 1124; // arbitrarily picked. Has to be different to server port (7080)
  const prodPublicPath =
    SIMORGH_PUBLIC_STATIC_ASSETS_ORIGIN + SIMORGH_PUBLIC_STATIC_ASSETS_PATH;

  const clientConfig = {
    name: BUNDLE_TYPE,
    target: ['web', IS_LEGACY_WEB ? 'es5' : 'es2017'], // compile for browser environment
    entry: START_DEV_SERVER
      ? ['webpack/hot/only-dev-server', './src/client']
      : [
          IS_LEGACY_WEB ? './src/poly/legacy.js' : './src/poly/modern.js',
          './src/client',
        ],
    devServer: {
      host: 'localhost',
      port: webpackDevServerPort,
      historyApiFallback: true,
      hot: true,
      headers: {
        'Access-Control-Allow-Origin': '*',
      },
      allowedHosts: 'all',
    },
    resolve: {
      fallback: {
        // Override webpacks default handling for these as they arnt availible on the client.
        fs: false,
        crypto: false,
        stream: require.resolve('stream-browserify'),
        https: false,
        http: false,
        tls: false,
      },
    },
    experiments: {
      outputModule: !IS_LEGACY_WEB,
    },
    output: {
      module: !IS_LEGACY_WEB,
      path: resolvePath('build/public'),
      /**
       * Need unhashed client bundle when running dev server.
       * Though we're no longer using Razzle, there is a good explanation here:
       * https://github.com/jaredpalmer/razzle/tree/master/packages/create-razzle-app/templates/default#how-razzle-works-the-secret-sauce
       */
      filename: START_DEV_SERVER
        ? `static/js/${BUNDLE_TYPE}.[name].js`
        : `static/js/${BUNDLE_TYPE}.[name].[chunkhash:8].js`, // hash based on the contents of the file
      // need full URL for dev server & HMR: https://github.com/webpack/docs/wiki/webpack-dev-server#combining-with-an-existing-server
      publicPath: START_DEV_SERVER
        ? `http://localhost:${webpackDevServerPort}/`
        : prodPublicPath,
    },
    optimization: {
      moduleIds: 'deterministic',
      minimizer: [
        new TerserPlugin({
          terserOptions: {
            // These options are enabled in production profile builds only and
            // prevent the discarding or mangling of class and function names.
            ecma: IS_LEGACY_WEB ? 5 : 2017,
            keep_classnames: IS_PROD_PROFILE,
            keep_fnames: IS_PROD_PROFILE,
            compress: {
              passes: 2,
            },
          },
        }),
      ],
      // specify min/max file sizes for each JS chunk for optimal performance
      splitChunks: {
        chunks: 'all',
        automaticNameDelimiter: '-',
        maxSize: 245760, // 240kb
        cacheGroups: {
          default: false,
          defaultVendors: false,
          framework: {
            name: 'framework',
            chunks: 'all',
            // This regex ignores nested copies of framework libraries so they're bundled with their issuer.
            test: new RegExp(
              `(?<!node_modules.*)[\\\\/]node_modules[\\\\/](${FRAMEWORK_BUNDLES.join(
                `|`,
              )})[\\\\/]`,
            ),
            priority: 40,
            // Don't let webpack eliminate this chunk (prevents this chunk from becoming a part of the commons chunk)
            enforce: true,
          },
          commons: {
            name: 'commons',
            // if a chunk is used on all pages we put it in commons
            minChunks: TOTAL_PAGE_TYPES,
            priority: 20,
          },
          lib: {
            // if a module is bigger than 160kb from node_modules we make a separate chunk for it
            test(module) {
              return (
                module.size() > 160000 &&
                /node_modules[/\\]/.test(module.identifier())
              );
            },
            name(module) {
              const rawRequest =
                module.rawRequest &&
                module.rawRequest.replace(/^@(\w+)[/\\]/, '$1-');
              if (rawRequest) return `${rawRequest}-lib`;

              const identifier = module.identifier();
              const trimmedIdentifier = /(?:^|[/\\])node_modules[/\\](.*)/.exec(
                identifier,
              );
              const processedIdentifier =
                trimmedIdentifier &&
                trimmedIdentifier[1].replace(/^@(\w+)[/\\]/, '$1-');

              return `${processedIdentifier || identifier}-lib`;
            },
            priority: 30,
            minChunks: 1,
            reuseExistingChunk: true,
          },
          shared: {
            name(module, chunks) {
              const chunkName = chunks.map(({ name }) => name).join('-');
              const cryptoName = crypto
                .createHash('sha1')
                .update(chunkName)
                .digest('base64');

              return [
                'shared',
                chunkName === 'russian-ukrainian' ? chunkName : cryptoName,
              ]
                .join('-')
                .replace(/[=+/]/g, '');
            },
            priority: 10,
            minChunks: 2,
            reuseExistingChunk: true,
          },
        },
        // Keep maximum initial requests to 25
        maxInitialRequests: 25,
        // A chunk should be at least 20kb before using splitChunks
        minSize: 20000,
      },
    },
    node: {
      __filename: 'mock',
    },
    plugins: [
      // copy static files otherwise untouched by Webpack, e.g. favicon
      ...(BUNDLE_TYPE === 'modern'
        ? [
            new CopyWebpackPlugin({
              patterns: [{ from: 'public' }],
            }),
          ]
        : []),
      new DuplicatePackageCheckerPlugin({
        // Emit compilation warning or error? (Default: `false`)
        emitError: true,
        // Display full duplicates information? (Default: `false`)
        verbose: true,
        exclude({ name, path }) {
          return (
            name === '@babel/runtime' &&
            [
              './~/@emotion/react/~/@babel/runtime',
              './~/@loadable/component/~/@babel/runtime',
              './~/react-router-dom/~/@babel/runtime',
            ].includes(path)
          );
        },
      }),
      /*
       * webpack 5 does no longer includes a polyfill for the Node.js process variable in
       * frontend code. webpack advise to avoid using it in the frontend code however the
       * following plugin will enable the process variable in frontend code until we find
       * an alternative for this sort of thing.
       */
      new webpack.ProvidePlugin({
        process: 'process/browser',
      }),
      new webpack.DefinePlugin({
        'process.env': getClientEnvVars(DOT_ENV_CONFIG),
      }),
      /*
       * This replaces calls to logger.node.js with logger.web.js, a client
       * side replacement, when building the bundle code for the client.
       * This avoids the weight of winston being included in the bundles and
       * issues arising from it trying to the use the file system
       */
      new webpack.NormalModuleReplacementPlugin(
        /(.*)logger.node(\.*)/,
        resource => {
          // eslint-disable-next-line no-param-reassign
          resource.request = resource.request.replace(
            /logger.node/,
            `logger.web`,
          );
        },
      ),
      /*
       * Exclude all moment locales so they can be included within service bundles
       */
      new webpack.IgnorePlugin({
        resourceRegExp: /^\.\/locale$/,
        contextRegExp: /moment$/,
      }),
      // keep track of the generated chunks
      // this determines what scripts get put in the footer of the page
      new LoadablePlugin({
        filename: `${BUNDLE_TYPE}-loadable-stats-${APP_ENV}.json`,
        writeToDisk: true,
      }),
    ],
  };

  if (IS_PROD) {
    const CompressionPlugin = require('compression-webpack-plugin');

    clientConfig.plugins.push(
      /**
       * Compresses Webpack assets with gzip Content-Encoding.
       * https://github.com/webpack-contrib/compression-webpack-plugin
       */
      new CompressionPlugin({
        algorithm: 'gzip',
        test: /\.js$/,
        threshold: 10240,
        minRatio: 0.8,
      }),
    );
  }
  if (IS_PROD) {
    const { BundleAnalyzerPlugin } = require('webpack-bundle-analyzer'); // eslint-disable-line
    /**
     * Visualize size of webpack output files with an interactive zoomable treemap.
     * https://github.com/webpack-contrib/webpack-bundle-analyzer
     */
    clientConfig.plugins.push(
      new BundleAnalyzerPlugin({
        analyzerMode: 'static',
        defaultSizes: 'gzip',
        generateStatsFile: true,
        openAnalyzer: false,
        reportFilename: `../../reports/${BUNDLE_TYPE}.webpackBundleReport.html`,
        statsFilename: `../../reports/${BUNDLE_TYPE}.webpackBundleReport.json`,
      }),
    );
  }
  return clientConfig;
};