@scalar/build-tooling/src/rollup-plugins/emptyOutDir.ts

Build tooling and helpers

import { rm } from 'node:fs/promises'

import type { Plugin } from 'rollup'

/**
 * Remove all files in a directory before writing to it
 * Taken from rollup/rollup
 *
 * @see https://github.com/rollup/rollup/blob/master/build-plugins/clean-before-write.ts
 */
export default function emptyOutDir({ dir }: { dir: string }): Plugin {
  let removePromise: Promise<void>

  return {
    name: 'empty-out-dir',
    generateBundle: {
      // Run before all other `generateBundle` plugins
      order: 'pre',
      handler(_options, _bundle, isWrite) {
        if (isWrite) {
          // Only remove before first write, but make all writes wait on the removal
          removePromise ??= rm(dir, {
            force: true,
            recursive: true,
          })

          return removePromise
        }
      },
    },
  }
}