now-sync/util/watch.js

A tool to help developers sync their JavaScript resources with ServiceNow.

const _ = require('lodash');
const chokidar = require('chokidar');
const fs = require('fs');
const path = require('path');
const Promise = require('bluebird');

const { getFieldValuesFromFileName } = require('./file-naming');
const { parseConfigFile, saveConfigFile } = require('./config');
const { updateRecord } = require('./service-now');

const readFileAsync = Promise.promisify(fs.readFile);

/**
 * Watches the configured directory for any file changes and updates the related ServiceNow record.
 *
 * When a file changes, the sync’d ServiceNow record’s field is updated with the file contents.
 * When a file is deleted, the file is removed from the .now-sync.yml configuration file.
 *
 * @returns {chokidar} A chokidar watcher instance
 */
function watch(cb) {
  const config = parseConfigFile();
  const dir = path.resolve(process.cwd(), config.filePath);

  const watcher = chokidar.watch(dir, {
    awaitWriteFinish: true,
    ignored: /(^|[/\\])\../, // dotfiles
  });

  watcher.on('ready', () => {
    cb(null, 'ready');
  });

  // Used for storing the file’s mtime (last modified time) before changes are made.
  // This is so we can compare whether the ServiceNow record was updated before the
  // user made their latest change.
  const fileStats = {};

  watcher.on('add', (watchPath, stats) => {
    fileStats[watchPath] = stats;

    cb(null, 'add', stats);
  });

  watcher.on('change', async (watchPath, stats) => {
    const latestConfig = parseConfigFile();
    const relativePath = watchPath.substr(dir.length + 1).split(path.sep);
    const table = relativePath[0];
    const file = relativePath[1];

    const fileConfig = _.find(
      latestConfig.records[table],
      (record) => record.fileName === file
    );
    if (!fileConfig) {
      cb(
        new Error(
          `Could not find a file configuration matching table record on ${table}: ${file}. Make sure that configuration exists in your .now-sync.yml file. If it does not exist, run \`now add\` to add the file configuration.`
        )
      );
      return;
    }

    const { contentField } = fileConfig;
    const { fileName: fileTemplate } = _.find(
      latestConfig.config[table].formats,
      (format) => format.contentField === contentField
    );
    const fieldValues = getFieldValuesFromFileName(file, fileTemplate);

    const fileContents = await readFileAsync(watchPath, 'utf8');
    const uploadBody = {};
    uploadBody[contentField] = fileContents;
    const updateRecordResponse = await updateRecord(
      table,
      fieldValues.sys_id,
      uploadBody
    );
    fileStats[watchPath] = stats;

    cb(null, 'change', stats, {
      table,
      sysId: fieldValues.sys_id,
      response: updateRecordResponse,
    });
  });

  watcher.on('unlink', (watchPath) => {
    delete fileStats[watchPath];
    const latestConfig = parseConfigFile();

    const relativePath = watchPath.substr(dir.length + 1).split(path.sep);
    const table = relativePath[0];
    const file = relativePath[1];

    const configRecords = latestConfig.records[table];
    const configRecordIndex = _.findIndex(
      configRecords,
      (record) => record.fileName === file
    );

    if (configRecordIndex > -1) {
      configRecords.splice(configRecordIndex, 1);

      saveConfigFile(latestConfig);
      cb(null, 'unlink', null, { path: watchPath, table, file });
    }
  });

  return watcher;
}
exports.watch = watch;