import { IncomingMessage } from 'http';
import { Http2ServerRequest } from 'http2';

const HOST_NORMALIZE_REGEX = /(^www\.)?([^:]+)(:\d+)?$/;

export function normalizeHost(host: string): string {
  const match = HOST_NORMALIZE_REGEX.exec(host.toLowerCase());
  return match ? match[2] : host;
}

export function resolveHostFromRequest(req: IncomingMessage|Http2ServerRequest): string {
  const authority: string = req.headers[':authority'] as string|undefined;
  return normalizeHost(authority ||
    req.headers.host ||
    'unknown')
  ;
}

export function resolveIpFromRequest(req: IncomingMessage|Http2ServerRequest, behindProxy = false): string {
  // for security reasons, we should never ASSUME the server is behind a proxy
  // and only support `x-forwarded-for` is explicitly enabled
  const forwardedFor: string = behindProxy && req.headers['x-forwarded-for'] as string|undefined;
  return forwardedFor ||
    req?.socket?.remoteAddress ||
    'unknown'
  ;
}