rollup.config.js

import ts from '@rollup/plugin-typescript';
import { builtinModules } from 'node:module';
import path from 'node:path';
import { defineConfig } from 'rollup';
import flatDts from 'rollup-plugin-flat-dts';
import typescript from 'typescript';

const externalModules = new Set([...builtinModules, 'deepmerge', 'jest', 'typescript']);

export default defineConfig({
  input: {
    'project-config': './src/mod.ts',
    'rollup.config': './src/rollup.config.js/main.ts',
  },
  plugins: [
    ts({
      typescript,
      tsconfig: './tsconfig.main.json',
      cacheDir: 'target/.ts_cache',
    }),
  ],
  external(id) {
    return (
      id.startsWith('node:') ||
      externalModules.has(id) ||
      id.startsWith('rollup') ||
      id.startsWith('@run-z/') ||
      id.startsWith('@rollup/')
    );
  },
  output: {
    dir: 'dist',
    format: 'esm',
    sourcemap: true,
    entryFileNames: '[name].js',
    chunkFileNames: '_[name].js',
    manualChunks(id) {
      if (id.startsWith(path.resolve('src', 'rollup.config.js'))) {
        return 'rollup.config.js';
      }
      if (id.startsWith(path.resolve('src'))) {
        return 'project-config';
      }
    },
    plugins: [
      flatDts({
        tsconfig: './tsconfig.main.json',
        lib: true,
        file: 'project-config.d.ts',
        compilerOptions: {
          declarationMap: true,
        },
        entries: {
          'rollup.config.js': {
            file: './rollup.config.d.ts',
          },
        },
        internal: ['**/impl/**', '**/*.impl'],
      }),
    ],
  },
});