@web/rollup-plugin-html/src/input/addRollupInput.ts

Rollup plugin for bundling HTML files

import { InputOptions } from 'rollup';
import { ScriptModuleTag } from '../RollupPluginHTMLOptions.js';
import { createError } from '../utils.js';

function fromEntries<V>(entries: [string, V][]) {
  const obj: Record<string, V> = {};
  for (const [k, v] of entries) {
    obj[k] = v;
  }
  return obj;
}

export function addRollupInput(
  inputOptions: InputOptions,
  inputModuleIds: ScriptModuleTag[],
): InputOptions {
  // Add input module ids to existing input option, whether it's a string, array or object
  // this way you can use multiple html plugins all adding their own inputs
  if (!inputOptions.input) {
    return { ...inputOptions, input: inputModuleIds.map(mod => mod.importPath) };
  }

  if (typeof inputOptions.input === 'string') {
    return {
      ...inputOptions,
      input: [
        ...(inputOptions?.input?.endsWith('.html') ? [] : [inputOptions.input]),
        ...inputModuleIds.map(mod => mod.importPath),
      ],
    };
  }

  if (Array.isArray(inputOptions.input)) {
    return {
      ...inputOptions,
      input: [...inputOptions.input, ...inputModuleIds.map(mod => mod.importPath)],
    };
  }

  if (typeof inputOptions.input === 'object') {
    return {
      ...inputOptions,
      input: {
        ...inputOptions.input,
        ...fromEntries(
          inputModuleIds
            .map(mod => mod.importPath)
            .map(i => [i.split('/').slice(-1)[0].split('.')[0], i]),
        ),
      },
    };
  }

  throw createError(`Unknown rollup input type. Supported inputs are string, array and object.`);
}