import { IncomingMessage, ServerResponse } from 'http';
import url from 'url';
import urlJoin from 'url-join';
import createDebug from '../utils/debug';
import { Config, LogoutOptions } from '../config';
import { ClientFactory } from '../client';
import { SessionCache } from '../session-cache';

const debug = createDebug('logout');

export type HandleLogout = (req: IncomingMessage, res: ServerResponse, options?: LogoutOptions) => Promise<void>;

export default function logoutHandlerFactory(
  config: Config,
  getClient: ClientFactory,
  sessionCache: SessionCache
): HandleLogout {
  return async (req, res, options = {}) => {
    let returnURL = options.returnTo || config.routes.postLogoutRedirect;
    debug('logout() with return url: %s', returnURL);

    if (url.parse(returnURL).host === null) {
      returnURL = urlJoin(config.baseURL, returnURL);
    }

    if (!sessionCache.isAuthenticated(req, res)) {
      debug('end-user already logged out, redirecting to %s', returnURL);
      res.writeHead(302, {
        Location: returnURL
      });
      res.end();
      return;
    }

    const idToken = sessionCache.getIdToken(req, res);
    sessionCache.delete(req, res);

    if (!config.idpLogout) {
      debug('performing a local only logout, redirecting to %s', returnURL);
      res.writeHead(302, {
        Location: returnURL
      });
      res.end();
      return;
    }

    const client = await getClient();
    returnURL = client.endSessionUrl({
      post_logout_redirect_uri: returnURL,
      id_token_hint: idToken
    });
    returnURL = `${returnURL}&idToken=${idToken}`;

    debug('logging out of identity provider, redirecting to %s', returnURL);
    res.writeHead(302, {
      Location: returnURL
    });
    res.end();
  };
}