import type http from 'http';
import type { ApolloServerPlugin } from '../../externalTypes/index.js';
import { Stopper } from './stoppable.js';

/**
 * Options for ApolloServerPluginDrainHttpServer.
 */
export interface ApolloServerPluginDrainHttpServerOptions {
  /**
   * The http.Server (or https.Server, etc) to drain. Required.
   */
  httpServer: http.Server;
  /**
   * How long to wait before forcefully closing non-idle connections.
   * Defaults to 10_000 (ten seconds).
   */
  stopGracePeriodMillis?: number;
}

/**
 * This plugin is used with frameworks built on Node's http.Server
 * (`startStandaloneServer`, Express, etc) to drain your HTTP server on
 * shutdown. See
 * https://www.apollographql.com/docs/apollo-server/api/plugin/drain-http-server/
 * for details.
 */
export function ApolloServerPluginDrainHttpServer(
  options: ApolloServerPluginDrainHttpServerOptions,
): ApolloServerPlugin {
  const stopper = new Stopper(options.httpServer);
  return {
    async serverWillStart() {
      return {
        async drainServer() {
          const stopGracePeriodMillis = options.stopGracePeriodMillis ?? 10_000;
          const signal = AbortSignal.timeout(stopGracePeriodMillis);
          await stopper.stop(signal);
        },
      };
    },
  };
}