app.js

const EventEmitter = require("events");
const architect = require("architect");
const debug = require("debug");
const chalk = require("chalk");
const lodash = require("lodash");
const path = require("path");

const expr = require("./utils/expressions");
const packageJSON = require("./package.json");

const CORE_CONFIG_PATH = path.join(__dirname, "conf.js");
const EVENTS = {
  APPLICATION_READY: "APPLICATION:READY",
  APPLICATION_SHUTDOWN: "APPLICATION:SHUTDOWN",
  SERVICE_REGISTERED: "SERVICE:REGISTERED",
  PLUGIN_REGISTERED: "PLUGIN:REGISTERED"
};
let shutdownWasCalled = false;
const log = debug(`${packageJSON.name}:app`);

const shutdown = function() {
  expr.whenFalse(shutdownWasCalled, () => {
    shutdownWasCalled = true;
    let counter = this.listeners(EVENTS.APPLICATION_SHUTDOWN).length;
    expr.whenTrue(counter === 0, process.exit.bind(process, 0));

    // count the handlers , and when handler call next, augment +1 counter
    // when counter is equal to the handler , close in a 'sign kill'
    this.emit(EVENTS.APPLICATION_SHUTDOWN, () => {
      counter--;
      if (counter <= 0) {
        // kill process in a sigterm
        process.exit(1);
      }
    });
  });
};

class App extends EventEmitter {
  get events() {
    return EVENTS;
  }

  constructor() {
    super();
    this.services = null;

    const bindedShutdown = shutdown.bind(this);
    process.on("SIGINT", bindedShutdown);
    process.on("SIGTERM", bindedShutdown);
  }

  start(configPath) {
    // creating built in core plugins config
    const coreConfig = architect.loadConfig(CORE_CONFIG_PATH);

    // creating client config
    const clientConfig = architect.loadConfig(configPath);

    const config = [...coreConfig, ...clientConfig];

    architect.createApp(config, (err, app) => {
      if (err) {
        log(chalk.red("Was an error creating architect pipe flow app"));
        log(err);
        throw err;
      }

      app.on("service", this.emit.bind(this, EVENTS.SERVICE_REGISTERED));
      app.on("plugin", this.emit.bind(this, EVENTS.PLUGIN_REGISTERED));
      // set services to provide using app.service
      this.services = app.services;
      log(chalk.green("Sherminator is ready :)"));
      this.emit(EVENTS.APPLICATION_READY);
    });
  }

  service(pattern) {
    return lodash.get(this.services, pattern);
  }
}

module.exports = App;