import path from 'path';

const safeResolve = (name: string, where: string[]): string | Error => {
  try {
    return require.resolve(name, {
      paths: where,
    });
  } catch (e: unknown) {
    return e as Error;
  }
};

const suffixes = ['.js', '.ts', '.jsx', '.tsx'].reduce((acc: string[], ext) => {
  acc.push(`/index${ext}`);
  acc.push(ext);
  return acc;
}, []);

export const syncResolve = (
  what: string,
  importer: string,
  stack: string[]
): string => {
  const where = [importer, ...stack].map((p) => path.dirname(p));
  const resolved = safeResolve(what, where);
  if (!(resolved instanceof Error)) {
    return resolved;
  }

  // eslint-disable-next-line no-restricted-syntax
  for (const suffix of suffixes) {
    const resolvedWithSuffix = safeResolve(what + suffix, where);
    if (resolvedWithSuffix instanceof Error) {
      // eslint-disable-next-line no-continue
      continue;
    }

    return resolvedWithSuffix;
  }

  throw resolved;
};

const asyncResolve = (
  what: string,
  importer: string,
  stack: string[]
): Promise<string> => {
  const where = [importer, ...stack].map((p) => path.dirname(p));
  const resolved = safeResolve(what, where);
  if (!(resolved instanceof Error)) {
    return Promise.resolve(resolved);
  }

  // eslint-disable-next-line no-restricted-syntax
  for (const suffix of suffixes) {
    const resolvedWithSuffix = safeResolve(what + suffix, where);
    if (resolvedWithSuffix instanceof Error) {
      // eslint-disable-next-line no-continue
      continue;
    }

    return Promise.resolve(resolvedWithSuffix);
  }

  throw resolved;
};

export default asyncResolve;