import { ServerOptions, createExpressServer } from "@nimbus/server";
import { ApolloServer } from "apollo-server-express";
import { GetMiddlewareOptions } from "apollo-server-express/src/ApolloServer";
import { Application } from "express";
import { createServer, Server, ClientRequest } from "http";
import { ApolloServerConfig, createApolloServer } from "./apollo";

export interface ApolloServerExpress extends ApolloServerConfig {
  server?: GetMiddlewareOptions & ServerOptions,
}

/**
 * A configured ready to use graphql server
 */
export class GraphQLServer {
  _server: Server;
  private readonly _express: Application;
  private readonly _apollo: ApolloServer;

  constructor(
      private readonly _serverOptions: ApolloServerExpress,
      _express?: Application,
  ) {
    this._express = _express || createExpressServer(_serverOptions.server);
    this._server = createServer(this._express);
    this._apollo = createApolloServer(_serverOptions);
  }

  public prepare() {
    this.apollo.applyMiddleware({ app: this.express, ...this._serverOptions.server });

    if (this._serverOptions.subscriptions) {
      this.apollo.installSubscriptionHandlers(this._server);
    }

    return this;
  }

  get server() {
    return this._server;
  }

  get express() {
    return this._express;
  }

  get apollo() {
    return this._apollo;
  }

  on: Server["on"] = (...args: Parameters<ClientRequest["on"]>) => {
    return this._server.on(args[0] as string, args[1]);
  };

  listen(port: number) {
    this.prepare();

    return new Promise((resolve, reject) => {
      this._server.on('listening', () => {
        resolve();
      });

      this._server.on("error", (error: Error) => {
        reject(error);
      });

      this._server.listen(port);
    });
  }

  close() {
    return new Promise((resolve, reject) => {
      this._server.close((err) => {
        if (err) {
          reject(err);
        } else {
          resolve();
        }
      });

      setImmediate(() => {
        this._server.emit('close');
      });
    });
  }
}