ThinkDeepTech/thinkdeep

import {getPublicIP} from '@thinkdeep/get-public-ip';

/**
 * Object representing the microservice itself.
 */
class Microservice {
  /**
   * @param {object} apolloServer - Apollo server instance.
   * @param {object} expressApp - Express instance.
   * @param {object} logger - The logger to use.
   */
  constructor(apolloServer, expressApp, logger) {
    this._apolloServer = apolloServer;
    this._expressApp = expressApp;
    this._logger = logger;
  }

  /**
   * Start server listener.
   */
  async listen() {
    this._logger.info(`Starting apollo server.`);
    await this._apolloServer.start();

    this._expressApp.disable('x-powered-by');

    // NOTE: Placing a forward slash at the end of any allowed origin causes a preflight error.
    let allowedOrigins = [
      'https://predecos.com',
      'https://www.predecos.com',
      'https://thinkdeep-d4624.web.app',
      'https://www.thinkdeep-d4624.web.app',
    ];
    const production = process.env.NODE_ENV.toLowerCase() === 'production';
    if (!production) {
      allowedOrigins = allowedOrigins.concat([
        /^https?:\/\/localhost:\d{1,5}/,
        'https://studio.apollographql.com',
      ]);
    }

    const path = process.env.GRAPHQL_PATH;
    if (!path) {
      throw new Error(
        `A path at which the application can be accessed is required (i.e, /graphql). Received: ${path}`
      );
    }

    this._logger.debug(`Applying middleware.`);
    this._apolloServer.applyMiddleware({
      app: this._expressApp,
      path,
      cors: {
        origin: allowedOrigins,
        methods: 'GET,HEAD,PUT,PATCH,POST,DELETE,OPTIONS,CONNECT,TRACE',
        credentials: true,
      },
    });

    const port = Number(process.env.GRAPHQL_PORT);
    if (!port) {
      throw new Error(
        `A port at which the application can be accessed is required. Received: ${port}`
      );
    }

    await new Promise((resolve) => this._expressApp.listen({port}, resolve));
    this._logger.info(
      `🚀 Server ready at http://${getPublicIP()}:${port}${
        this._apolloServer.graphqlPath
      }`
    );
  }
}

export {Microservice};