import babel from '@babel/core';

const babelOptions = {

  babelrc: false,

  ignore: [/\/(build|node_modules)\//],

  plugins: [

    '@babel/plugin-syntax-import-meta',

    '@babel/plugin-transform-react-jsx',

  ],

};

export async function load(url, context, defaultLoad) {

  const {format} = context;

  const result = await defaultLoad(url, context, defaultLoad);

  if (result.format === 'module') {

    const opt = Object.assign({filename: url}, babelOptions);

    const newResult = await babel.transformAsync(result.source, opt);

    if (!newResult) {

      if (typeof result.source === 'string') {

        return result;

      }

      return {

        source: Buffer.from(result.source).toString('utf8'),

        format: 'module',

      };

    }

    return {source: newResult.code, format: 'module'};

  }

  return defaultLoad(url, context, defaultLoad);

}

async function babelTransformSource(source, context, defaultTransformSource) {

  const {format} = context;

  if (format === 'module') {

    const opt = Object.assign({filename: context.url}, babelOptions);

    const newResult = await babel.transformAsync(source, opt);

    if (!newResult) {

      if (typeof source === 'string') {

        return {source};

      }

      return {

        source: Buffer.from(source).toString('utf8'),

      };

    }

    return {source: newResult.code};

  }

  return defaultTransformSource(source, context, defaultTransformSource);

}

export const transformSource =

  process.version < 'v16' ? babelTransformSource : undefined;