// Note: express is only used if you use the ApolloServer.listen API to create
// an express app for you instead of applyMiddleware (which you might not even
// use with express). The dependency is unused otherwise, so don't worry if
// you're not using express or your version doesn't quite match up.
import {
  ApolloServer as ApolloServerBase,
  Config,
  CorsOptions,
} from 'apollo-server-express'
import express from 'express'
import http from 'http'
import net from 'net'

export interface ServerInfo {
  address: string
  family: string
  url: string
  subscriptionsUrl: string
  port: number | string
  subscriptionsPath: string
  server: http.Server
}

export class ApolloServer extends ApolloServerBase {
  public express: express.Express
  private httpServer?: http.Server
  private cors?: CorsOptions | boolean
  private path?: string

  constructor(
    config: Config & {
      cors?: CorsOptions | boolean
      express?: express.Express
      path?: string
    },
  ) {
    super(config)
    this.cors = config && config.cors
    this.path = config && config.path
    this.express =
      (config && config.express) || (express && express())
  }

  private createServerInfo(
    server: http.Server,
    subscriptionsPath?: string,
  ): ServerInfo {
    const serverInfo: any = {
      ...(server.address() as net.AddressInfo),
      server,
      subscriptionsPath,
    }

    // Convert IPs which mean "any address" (IPv4 or IPv6) into localhost
    // corresponding loopback ip. Note that the url field we're setting is
    // primarily for consumption by our test suite. If this heuristic is
    // wrong for your use case, explicitly specify a frontend host (in the
    // `frontends.host` field in your engine config, or in the `host`
    // option to ApolloServer.listen).
    let hostForUrl = serverInfo.address
    if (serverInfo.address === '' || serverInfo.address === '::') {
      hostForUrl = 'localhost'
    }

    serverInfo.url = require('url').format({
      protocol: 'http',
      hostname: hostForUrl,
      port: serverInfo.port,
      pathname: this.graphqlPath,
    })

    serverInfo.subscriptionsUrl = require('url').format({
      protocol: 'ws',
      hostname: hostForUrl,
      port: serverInfo.port,
      slashes: true,
      pathname: subscriptionsPath,
    })

    return serverInfo
  }

  public applyMiddleware() {
    throw new Error(
      'To use Apollo Server with an existing express application, please use apollo-server-express',
    )
  }

  // Listen takes the same arguments as http.Server.listen.
  public async prepare() {
    await this.willStart()

    // This class is the easy mode for people who don't create their own express
    // object, so we have to create it.
    const app = this.express

    // provide generous values for the getting started experience
    super.applyMiddleware({
      app,
      path: this.path || '/',
      bodyParserConfig: { limit: '50mb' },
      cors:
        typeof this.cors !== 'undefined'
          ? this.cors
          : {
              origin: '*',
            },
    })

    const httpServer = http.createServer(app)
    this.httpServer = httpServer

    if (this.subscriptionServerOptions) {
      this.installSubscriptionHandlers(httpServer)
    }

    const listen = async (...opts: Array<any>) => {
      await new Promise(resolve => {
        httpServer.once('listening', resolve)
        // If the user passed a callback to listen, it'll get called in addition
        // to our resolver. They won't have the ability to get the ServerInfo
        // object unless they use our Promise, though.
        httpServer.listen(...(opts.length ? opts : [{ port: 4000 }]))
      })

      return this.createServerInfo(httpServer, this.subscriptionsPath)
    }

    return listen
  }

  listen(...opts: Array<any>): Promise<ServerInfo> {
    return this.prepare().then(startListening =>
      startListening(...opts),
    )
  }

  public async stop() {
    if (this.httpServer) {
      const httpServer = this.httpServer
      await new Promise(resolve => httpServer.close(resolve))
      this.httpServer = undefined
    }
    await super.stop()
  }
}