import assert from 'assert';
import { extname } from 'path';

export default function() {
  return {
    name: 'cssModulesExcludes',
    validate(val) {
      assert(Array.isArray(val), `The cssModulesExcludes config must be Array, but got ${val}`);
      val.forEach(file => {
        const ext = extname(file).toLowerCase();
        assert(
          ext === '.css' || ext === '.less',
          `Items in the cssModulesExcludes config must end with .css or .less, but got ${file}`,
        );
      });
    },
  };
}