import * as fs from 'fs';
import {
  resolvePackageUrl,
} from 'node-sass-magic-importer/dist/toolbox';
import { defaultOptions } from './default-options';

import { IPackageImporterOptions } from 'node-sass-magic-importer/dist/interfaces/IImporterOptions';

export = function packageImporter(userOptions?: IPackageImporterOptions) {
  const options = Object.assign({}, defaultOptions, userOptions);

  if (options.hasOwnProperty(`prefix`)) {
    process.emitWarning('Using the `prefix` option is not supported anymore, use `packagePrefix` instead.');
  }

  const escapedPrefix = options.packagePrefix.replace(/[-/\\^$*+?.()|[\]{}]/g, `\\$&`);
  const matchPackageUrl = new RegExp(`^${escapedPrefix}(?!/)`);

  return function importer(url: string) {
    if (!url.match(matchPackageUrl)) {
      return null;
    }

    const cleanedUrl = url.replace(matchPackageUrl, ``);
    const file = resolvePackageUrl(
      cleanedUrl,
      options.extensions,
      options.cwd,
      options.packageKeys,
    );

    if (!file) {
      return null;
    }

    if (/\.css$/.test(file)) {
      return { contents: fs.readFileSync(file, 'utf-8') };
    }

    return { file: file.replace(/\.css$/, ``) };
  };
};