ape-repo/ape-watching

/**
 * Watch files.
 * @memberof module:ape-watching/lib
 * @function watchFiles
 * @param {string|string} - Filenames to watch.
 * @param {object} [options] - Optional settings.
 * @param {string} [options.cwd] - Working directory path.
 * @param {string} [options.prefix] - Prefix for log
 * @param {function} handler - File change handler.
 */

'use strict'

const argx = require('argx')
const fs = require('fs')
const path = require('path')
const fwatcher = require('fwatcher')
const arrayfilter = require('arrayfilter')
const colorprint = require('colorprint')
const aglob = require('aglob')

/** @lends watchFiles */
function watchFiles (filenames, options, handler) {
  let args = argx(arguments)
  handler = args.pop('function') || argx.noop
  filenames = args.shift('string|array')
  options = args.pop('object') || {}

  let cwd = options.cwd || process.cwd()
  let prefix = options.prefix || 'ape-watching'
  filenames = aglob.sync(filenames, {
    cwd: cwd
  }).map((filename) =>
    path.resolve(cwd, filename)
  ).filter(fs.existsSync)
  colorprint.info('[%s] Start watch files...', prefix)
  colorprint.trace('%s', filenames.map((filename) => path.relative(process.cwd(), filename)))

  function _watchSingle (filename, options, listener) {
    if (!fs.existsSync(filename)) {
      return null
    }
    let watcher = fwatcher(filename, options, (err, event) => {
      if (err) {
        throw err
      }
      colorprint.debug('[%s] File changed: %s', prefix, path.relative(process.cwd(), filename))
      if (listener) {
        listener(event, filename)
      }
    })
    watcher.close = function () {
      watcher.off()
      let _ = watcher._
      if (_) {
        _.close()
      }
    }
    return watcher
  }

  return filenames.map((filename) => {
    return _watchSingle(filename, options, handler)
  }).filter(arrayfilter.emptyReject())
}

module.exports = watchFiles