import {buildConfig} from './build-config';
import MagicString from 'magic-string';

/** License banner from the build config that will be removed in all source files. */
const licenseBanner = buildConfig.licenseBanner;

/**
 * Rollup plugin that removes all license banners of source files.
 * This is necessary to avoid having the license comment repeated in the output.
 */
export const rollupRemoveLicensesPlugin = {
  name: 'rollup-clean-duplicate-licenses',
  transform: (code: string) => {
    const newContent = new MagicString(code);

    // Walks through every occurrence of a license comment and overwrites it with an empty string.
    for (let pos = -1; (pos = code.indexOf(licenseBanner, pos + 1)) !== -1; null) {
      newContent.overwrite(pos, pos + licenseBanner.length, '');
    }

    return {
      code: newContent.toString(),
      map:  newContent.generateMap({ hires: true })
    };
  }
};