bcgov/PIMS

import logger from '@/utilities/winstonLogger';
import constants from '@/constants';
import app from '@/express';
import { AppDataSource } from '@/appDataSource';
import { Application } from 'express';
import { IncomingMessage, Server, ServerResponse } from 'http';
import cronSyncKeycloakRoles from '@/utilities/cronJobs/syncKeycloakRoles';

const { API_PORT } = constants;

/**
 * Starts the application server and initializes the database connection.
 *
 * @param app - The Express application instance.
 * @returns The server instance.
 */
const startApp = (app: Application) => {
  const server = app.listen(API_PORT, async (err?: Error) => {
    if (err) logger.error(err);
    logger.info(`Server started on port ${API_PORT}.`);

    // creating connection to database
    await AppDataSource.initialize()
      .then(() => {
        logger.info('Database connection has been initialized');
      })
      .catch((err?: Error) => {
        logger.error('Error during data source initialization. With error: ', err);
      });

    // Starting cron jobs
    cronSyncKeycloakRoles();
  });

  return server;
};

// Start the server here.
// Set up in a way that the server could be restarted (reassigned) if needed.
let server: Server<typeof IncomingMessage, typeof ServerResponse>;
(async () => {
  server = await startApp(app);
})();

/**
 * Stops the application gracefully.
 *
 * @param exitCode - The exit code to be used when terminating the process.
 * @param e - Optional. The error message to be logged.
 *
 * @returns void
 */
const stopApp = async (exitCode: number, e?: string) => {
  logger.error(`${e ?? 'unknown'}`);
  // Database connection may not be initialized.
  if (AppDataSource.isInitialized) {
    logger.warn('Closing database connection.');
    await AppDataSource.destroy();
  }
  // Server may not be defined.
  if (server) {
    logger.warn('Closing user connections.');
    server.closeAllConnections();
    server.close(() => {
      logger.warn('Express application terminated.');
      process.exit(exitCode);
    });
  }
};

// Error catching listeners
process.on('uncaughtException', (err: Error) => {
  logger.warn('Uncaught exception received. Shutting down gracefully.');
  stopApp(1, err.stack);
});

process.on('unhandledRejection', (err: Error) => {
  logger.warn('Unhandled rejection received. Shutting down gracefully.');
  stopApp(1, err.stack);
});

// When termination call is received.
process.on('SIGTERM', () => {
  logger.warn('SIGTERM received. Shutting down gracefully.');
  stopApp(0, 'SIGTERM request.');
});