import { A } from '@ember/array';
import { isNone } from '@ember/utils';
import { Headers } from '../types';

/**
 * Do a case-insensitive lookup of an HTTP header
 *
 * @function getHeader
 * @private
 */
export default function getHeader(
  headers: Headers | undefined,
  name: string | undefined
): string | undefined | null {
  if (isNone(headers) || isNone(name)) {
    return undefined;
  }

  const matchedKey = A(Object.keys(headers)).find(key => {
    return key.toLowerCase() === name.toLowerCase();
  });

  return matchedKey ? headers[matchedKey] : undefined;
}