storybook/code/frameworks/nextjs/src/utils.ts

import path from 'path';
import { Configuration as WebpackConfig, DefinePlugin } from 'webpack';

export const configureRuntimeNextjsVersionResolution = (baseConfig: WebpackConfig): void => {
  baseConfig.plugins?.push(
    new DefinePlugin({
      'process.env.__NEXT_VERSION': JSON.stringify(getNextjsVersion()),
    })
  );
};

export const getNextjsVersion = (): string => require(scopedResolve('next/package.json')).version;

// This is to help the addon in development
// Without it, webpack resolves packages in its node_modules instead of the example's node_modules
export const addScopedAlias = (baseConfig: WebpackConfig, name: string, alias?: string): void => {
  baseConfig.resolve ??= {};
  baseConfig.resolve.alias ??= {};
  const aliasConfig = baseConfig.resolve.alias;

  const scopedAlias = scopedResolve(`${alias ?? name}`);

  if (Array.isArray(aliasConfig)) {
    aliasConfig.push({
      name,
      alias: scopedAlias,
    });
  } else {
    aliasConfig[name] = scopedAlias;
  }
};

/**
 *
 * @param id the module id
 * @returns a path to the module id scoped to the project folder without the main script path at the end
 * @summary
 * This is to help the addon in development.
 * Without it, the addon resolves packages in its node_modules instead of the example's node_modules.
 * Because require.resolve will also include the main script as part of the path, this function strips
 * that to just include the path to the module folder
 * @example
 * // before main script path truncation
 * require.resolve('styled-jsx') === '/some/path/node_modules/styled-jsx/index.js
 * // after main script path truncation
 * scopedResolve('styled-jsx') === '/some/path/node_modules/styled-jsx'
 */
export const scopedResolve = (id: string): string => {
  const scopedModulePath = require.resolve(id, { paths: [path.resolve()] });
  const moduleFolderStrPosition = scopedModulePath.lastIndexOf(
    id.replace(/\//g /* all '/' occurances */, path.sep)
  );
  const beginningOfMainScriptPath = moduleFolderStrPosition + id.length;
  return scopedModulePath.substring(0, beginningOfMainScriptPath);
};