rollup.config.js

import commonjs from '@rollup/plugin-commonjs';
import resolve from '@rollup/plugin-node-resolve';
import svelte from 'rollup-plugin-svelte';
import { terser } from 'rollup-plugin-terser';
import postcss from 'rollup-plugin-postcss';
import svg from 'rollup-plugin-svg';
import json from 'rollup-plugin-json';
import nodePolyfills from 'rollup-plugin-polyfill-node';
import copy from 'rollup-plugin-copy2';
import tar from 'tar';
import fs from 'fs';
import pkg from './package.json';
import crypto from 'crypto';
import autoPreprocess from 'svelte-preprocess';
import typescript from '@rollup/plugin-typescript';

const ignoredWarnings = [
  'unused-export-let',
  'css-unused-selector',
  'module-script-reactive-declaration',
  'a11y-no-onchange',
];

// Custom plugin to clean the dist folder before building
const clean = () => ({
  buildStart() {
    const dist = './dist/';
    if (fs.existsSync(dist)) {
      fs.readdirSync(dist).forEach(path => {
        if (path.endsWith('.tar.gz')) {
          fs.unlinkSync(dist + path);
        }
      });
    }
  },
});

// Custom plugin to hash the JS bundle and write it in the schema
const hash = () => ({
  writeBundle() {
    // Generate JS hash
    const fileBuffer = fs.readFileSync('dist/plugin.min.js');
    const hashSum = crypto.createHash('sha1');
    hashSum.update(fileBuffer);
    const hex = hashSum.digest('hex');

    // Read and parse existing schema from dist folder
    const schema = JSON.parse(fs.readFileSync('./dist/schema.json', 'utf8'));

    // Write updated schema to dist folder, pretty printed as JSON again
    const newSchema = {
      ...schema,
      hash: hex,
      version: pkg.version,
    };
    fs.writeFileSync('./dist/schema.json', JSON.stringify(newSchema, null, 2));
  },
});

// Custom plugin to bundle up our files after building
const bundle = () => ({
  async writeBundle() {
    const bundleName = `${pkg.name}-${pkg.version}.tar.gz`;
    return tar
      .c({ gzip: true, cwd: 'dist' }, [
        'plugin.min.js',
        'schema.json',
        'package.json',
      ])
      .pipe(fs.createWriteStream(`dist/${bundleName}`));
  },
});

export default {
  input: 'index.js',
  output: {
    sourcemap: process.env.ROLLUP_WATCH ? 'inline' : false,
    format: 'iife',
    file: 'dist/plugin.min.js',
    name: 'plugin',
    globals: {
      svelte: 'svelte',
      'svelte/internal': 'svelte_internal',
    },
  },
  external: ['svelte', 'svelte/internal'],
  plugins: [
    clean(),
    svelte({
      preprocess: autoPreprocess(),
      emitCss: true,
      onwarn: (warning, handler) => {
        // Ignore some warnings
        if (!ignoredWarnings.includes(warning.code)) {
          handler(warning);
        }
      },
    }),
    typescript(),
    postcss(),
    commonjs(),
    nodePolyfills(),
    resolve({
      preferBuiltins: true,
      browser: true,
      skip: ['svelte', 'svelte/internal'],
    }),
    svg({
      base64: true,
    }),
    json(),
    terser(),
    copy({
      assets: ['schema.json', 'package.json'],
    }),
    hash(),
    bundle(),
  ],
};