import {
  createLightship
} from 'lightship';

const configuration: LightshipConfigurationType = {};

const lightship: LightshipType = createLightship(configuration);

/**
 * A teardown function called when shutdown is initialized.
 */
type ShutdownHandlerType = () => Promise<void> | void;

/**
 * @property port The port on which the Lightship service listens. This port must be different than your main service port, if any. The default port is 9000.
 * @property signals An a array of [signal events]{@link https://nodejs.org/api/process.html#process_signal_events}. Default: [SIGTERM].
 * @property timeout A number of milliseconds before forcefull termination. Default: 60000.
 */
export type LightshipConfigurationType = {|
  +port?: number,
  +signals?: $ReadOnlyArray<string>,
  +timeout?: number
|};

/**
 * @property registerShutdownHandler Registers teardown functions that are called when shutdown is initialized. All registered shutdown handlers are executed in the order they have been registered. After all shutdown handlers have been executed, Lightship asks `process.exit()` to terminate the process synchronously.
 * @property shutdown Changes server state to SERVER_IS_SHUTTING_DOWN and initialises the shutdown of the application.
 * @property signalNotReady Changes server state to SERVER_IS_NOT_READY.
 * @property signalReady Changes server state to SERVER_IS_READY.
 */
type LightshipType = {|
  +isServerReady: () => boolean,
  +isServerShuttingDown: () => boolean,
  +registerShutdownHandler: (shutdownHandler: ShutdownHandlerType) => void,
  +shutdown: () => Promise<void>,
  +signalNotReady: () => void,
  +signalReady: () => void
|};

import express from 'express';

const app = express();

app.get('/', (req, res) => {
  res.send('Hello, World!');
});

app.listen(8080);

import express from 'express';
import {
  createLightship
} from 'lightship';

const app = express();

app.get('/', (req, res) => {
  res.send('Hello, World!');
});

const server = app.listen(8080);

const lightship = createLightship();

lightship.registerShutdownHandler(() => {
  server.close();
});

// Lightship default state is "SERVER_IS_NOT_READY". Therefore, you must signal
// that the server is now ready to accept connections.
lightship.signalReady();

import express from 'express';
import {
  createLightship
} from 'lightship';

const app = express();

const minute = 60 * 1000;

let runningTotal = 0;

app.get('/', (req, res) => {
  runningTotal++;

  setTimeout(() => {
    runningTotal--;

    if (runningTotal < 100) {
      lightship.signalReady();
    } else {
      lightship.signalNotReady();
    }
  }, minute);

  res.send('Hello, World!');
});

const server = app.listen(8080);

const lightship = createLightship();

lightship.registerShutdownHandler(() => {
  server.close();
});

// Lightship default state is "SERVER_IS_NOT_READY". Therefore, you must signal
// that the server is now ready to accept connections.
lightship.signalReady();

import express from 'express';
import delay from 'delay';
import {
  createLightship
} from 'lightship';

const app = express();

const minute = 60 * 1000;

let total = 0;
let runningTotal = 0;

app.get('/', (req, res) => {
  total++;
  runningTotal++;

  if (total === 1000) {
    lightship.shutdown();
  }

  setTimeout(() => {
    runningTotal--;

    if (runningTotal < 100) {
      lightship.signalReady();
    } else {
      lightship.signalNotReady();
    }
  }, minute);

  res.send('Hello, World!');
});

const server = app.listen(8080);

const lightship = createLightship();

lightship.registerShutdownHandler(async () => {
  // Allow sufficient amount of time to allow all of the existing
  // HTTP requests to finish before terminating the service.
  await delay(minute);

  server.close();
});

// Lightship default state is "SERVER_IS_NOT_READY". Therefore, you must signal
// that the server is now ready to accept connections.
lightship.signalReady();