files-monitor/app.js

Monitor files and inform if they changed

#!/usr/bin/env node

// TODO: Add param to generate empty ".filesmonitorrc".
// TODO: Refactor all this code later.

// Import.
const fs = require('fs');
const os = require('os');
const path = require('path');
const childProcess = require('child_process');
const md5File = require('md5-file');
const Sendmail = require('sendmail');

// Constants.
const HOME_DIR = os.homedir();
const USER_CONFIG_FILE = os.platform() === 'win32' ? 'filesmonitorrc' : '.filesmonitorrc';
const USER_CONFIG_PATH = path.join(HOME_DIR, USER_CONFIG_FILE);
const ENCODING = 'utf8';

// Init.
const sendmail = Sendmail({ silent: true });

// Inform.
console.log(`Files Monitor started with PID ${process.pid}.`);

// Define config.
let email;
let command;
let checkInterval;
let filesInfo = [];
try {
  const configContent = fs.readFileSync(USER_CONFIG_PATH, {
    encoding: ENCODING
  });
  const config = JSON.parse(configContent);
  filesInfo = config.files.map(v => ({ path: v, hash: null }));
  email = config.email;
  command = config.command;
  checkInterval = config.checkInterval;
  console.log(`Files to check: ${config.files.map(v => `"${v}"`).join(', ')}.`);
} catch (err) {
  console.log(`Can't define config in file "${USER_CONFIG_PATH}".`);
  process.exit(1);
}

// Check files.
setInterval(() => {
  for (let i = 0; i < filesInfo.length; i++) {
    const fileInfo = filesInfo[i];
    const previousHash = fileInfo.hash;
    let calculatedHash;
    try {
      calculatedHash = md5File.sync(fileInfo.path);
    } catch (err) {
      console.error(err);
    }
    const now = new Date();
    if (previousHash && calculatedHash !== previousHash) {
      // Inform.
      const message = `File "${fileInfo.path}" at "${os.hostname()}" changed accordance to check at ${now.toISOString()}.`;
      console.log(message);
      if (email) {
        try {
          sendmail({
            from: 'Files Monitor <noreply@example.com>',
            to: email,
            subject: 'Files Monitor alert',
            html: message
          });
        } catch (err) {
          console.error(err);
        }
      }

      // Run command.
      if (command) {
        console.log(`Command "${command}" started.`);
        childProcess.exec(command, (err, stdout) => {
          if (err) {
            console.error(err);
          }
          console.log(stdout);
        });
      }
    }
    fileInfo.hash = calculatedHash;
  }
}, checkInterval * 1000);