nx/packages/next/plugins/with-nx.ts

import type { NextConfig } from 'next';

export interface WithNxOptions extends NextConfig {
  nx?: {
    svgr?: boolean;
  };
}

export interface WithNxContext {
  workspaceRoot: string;
  libsDir: string;
}

function regexEqual(x, y) {
  return (
    x instanceof RegExp &&
    y instanceof RegExp &&
    x.source === y.source &&
    x.global === y.global &&
    x.ignoreCase === y.ignoreCase &&
    x.multiline === y.multiline
  );
}

/**
 * Do not remove or rename this function. Production builds inline `with-nx.js` file with a replacement
 * To this function that hard-codes the libsDir.
 */
function getWithNxContext(): WithNxContext {
  const { workspaceRoot, workspaceLayout } = require('@nrwl/devkit');
  return {
    workspaceRoot,
    libsDir: workspaceLayout().libsDir,
  };
}

export function withNx(
  nextConfig = {} as WithNxOptions,
  context: WithNxContext = getWithNxContext()
): NextConfig {
  // If `next-compose-plugins` is used, the context argument is invalid.
  if (!context.libsDir || !context.workspaceRoot) {
    context = getWithNxContext();
  }
  const userWebpack = nextConfig.webpack || ((x) => x);
  const { nx, ...validNextConfig } = nextConfig;
  return {
    eslint: {
      ignoreDuringBuilds: true,
      ...(validNextConfig.eslint ?? {}),
    },
    ...validNextConfig,
    webpack: (config, options) => {
      /*
       * Update babel to support our monorepo setup.
       * The 'upward' mode allows the root babel.config.json and per-project .babelrc files to be picked up.
       */
      options.defaultLoaders.babel.options.babelrc = true;
      options.defaultLoaders.babel.options.rootMode = 'upward';

      /*
       * Modify the Next.js webpack config to allow workspace libs to use css modules.
       * Note: This would be easier if Next.js exposes css-loader and sass-loader on `defaultLoaders`.
       */

      // Include workspace libs in css/sass loaders
      const includes = [
        require('path').join(context.workspaceRoot, context.libsDir),
      ];

      const nextCssLoaders = config.module.rules.find(
        (rule) => typeof rule.oneOf === 'object'
      );

      // webpack config is not as expected
      if (!nextCssLoaders) return config;

      /*
       *  1. Modify css loader to enable module support for workspace libs
       */
      const nextCssLoader = nextCssLoaders.oneOf.find(
        (rule) =>
          rule.sideEffects === false && regexEqual(rule.test, /\.module\.css$/)
      );
      // Might not be found if Next.js webpack config changes in the future
      if (nextCssLoader && nextCssLoader.issuer) {
        nextCssLoader.issuer.or = nextCssLoader.issuer.and
          ? nextCssLoader.issuer.and.concat(includes)
          : includes;
        delete nextCssLoader.issuer.and;
      }

      /*
       *  2. Modify sass loader to enable module support for workspace libs
       */
      const nextSassLoader = nextCssLoaders.oneOf.find(
        (rule) =>
          rule.sideEffects === false &&
          regexEqual(rule.test, /\.module\.(scss|sass)$/)
      );
      // Might not be found if Next.js webpack config changes in the future
      if (nextSassLoader && nextSassLoader.issuer) {
        nextSassLoader.issuer.or = nextSassLoader.issuer.and
          ? nextSassLoader.issuer.and.concat(includes)
          : includes;
        delete nextSassLoader.issuer.and;
      }

      /*
       *  3. Modify error loader to ignore css modules used by workspace libs
       */
      const nextErrorCssModuleLoader = nextCssLoaders.oneOf.find(
        (rule) =>
          rule.use &&
          rule.use.loader === 'error-loader' &&
          rule.use.options &&
          (rule.use.options.reason ===
            'CSS Modules \u001b[1mcannot\u001b[22m be imported from within \u001b[1mnode_modules\u001b[22m.\n' +
              'Read more: https://err.sh/next.js/css-modules-npm' ||
            rule.use.options.reason ===
              'CSS Modules cannot be imported from within node_modules.\nRead more: https://err.sh/next.js/css-modules-npm')
      );
      // Might not be found if Next.js webpack config changes in the future
      if (nextErrorCssModuleLoader) {
        nextErrorCssModuleLoader.exclude = includes;
      }

      /**
       * 4. Modify css loader to allow global css from node_modules to be imported from workspace libs
       */
      const nextGlobalCssLoader = nextCssLoaders.oneOf.find((rule) =>
        rule.include?.and?.find((include) =>
          regexEqual(include, /node_modules/)
        )
      );
      // Might not be found if Next.js webpack config changes in the future
      if (nextGlobalCssLoader && nextGlobalCssLoader.issuer) {
        nextGlobalCssLoader.issuer.or = nextGlobalCssLoader.issuer.and
          ? nextGlobalCssLoader.issuer.and.concat(includes)
          : includes;
        delete nextGlobalCssLoader.issuer.and;
      }

      /**
       * 5. Add env variables prefixed with NX_
       */
      addNxEnvVariables(config);

      /**
       * 6. Add SVGR support if option is on.
       */

      // Default SVGR support to be on for projects.
      if (nx?.svgr !== false) {
        config.module.rules.push({
          test: /\.svg$/,
          oneOf: [
            // If coming from JS/TS file, then transform into React component using SVGR.
            {
              issuer: /\.[jt]sx?$/,
              use: [
                {
                  loader: require.resolve('@svgr/webpack'),
                  options: {
                    svgo: false,
                    titleProp: true,
                    ref: true,
                  },
                },
                {
                  loader: require.resolve('url-loader'),
                  options: {
                    limit: 10000, // 10kB
                    name: '[name].[hash:7].[ext]',
                  },
                },
              ],
            },
            // Fallback to plain URL loader if someone just imports the SVG and references it on the <img src> tag
            {
              loader: require.resolve('url-loader'),
              options: {
                limit: 10000, // 10kB
                name: '[name].[hash:7].[ext]',
              },
            },
          ],
        });
      }

      return userWebpack(config, options);
    },
  };
}

function getNxEnvironmentVariables() {
  return Object.keys(process.env)
    .filter((env) => /^NX_/i.test(env))
    .reduce((env, key) => {
      env[key] = process.env[key];
      return env;
    }, {});
}

function addNxEnvVariables(config: any) {
  const maybeDefinePlugin = config.plugins?.find((plugin) => {
    return plugin.definitions?.['process.env.NODE_ENV'];
  });

  if (maybeDefinePlugin) {
    const env = getNxEnvironmentVariables();

    Object.entries(env)
      .map(([name, value]) => [`process.env.${name}`, `"${value}"`])
      .filter(([name]) => !maybeDefinePlugin.definitions[name])
      .forEach(
        ([name, value]) => (maybeDefinePlugin.definitions[name] = value)
      );
  }
}

// Support for older generated code: `const withNx = require('@nrwl/next/plugins/with-nx');`
module.exports = withNx;
// Support for newer generated code: `const { withNx } = require(...);`
module.exports.withNx = withNx;