import { resolve, join, dirname } from 'path' import { readFile, writeFile } from 'mz/fs' import { transform } from 'babel-core' import chokidar from 'chokidar' import mkdirp from 'mkdirp-then' export default babel async function babel (dir, { dev = false } = {}) { dir = resolve(dir) let src try { src = await readFile(join(dir, 'pages', '_document.js'), 'utf8') } catch (err) { if (err.code === 'ENOENT') { src = await readFile(join(__dirname, '..', '..', '..', 'pages', '_document.js'), 'utf8') } else { throw err } } const { code } = transform(src, { babelrc: false, sourceMaps: dev ? 'inline' : false, presets: [require.resolve('./preset')] }) const file = join(dir, '.next', 'dist', 'pages', '_document.js') await mkdirp(dirname(file)) await writeFile(file, code) } export function watch (dir) { return chokidar.watch('pages/_document.js', { cwd: dir, ignoreInitial: true }) }