util.js

const path   = require('path')
    , fs     = require('fs')
    , mkdirp = require('mkdirp')
    , vw     = require('visualwidth')


function repeat (ch, sz) {
  return new Array(sz + 1).join(ch)
}


function idFromName (id) {
  return id.toLowerCase()
    .replace(/\s/g, '_')
    .replace(/[^\w]/gi, '')
}


function dirFromName (exerciseDir, name) {
  return path.join(exerciseDir, idFromName(name))
}

function assertFs (type, options, field, base, fallback) {
  var target = options[field]
    , stat
  if (typeof target != 'string')
    if (fallback)
      options[field] = target = path.join(base, fallback)
    else
      throw new TypeError('need to provide an "' + field + '" String option')

  try {
    stat = fs.statSync(target)
  } catch (e) {}

  if (!stat || !(type === 'file' ? stat.isFile() : stat.isDirectory()))
    throw new Error('"' + field + '" [' + path.relative('.', target) + '] does not exist or is not a ' + type)

  return target
}

function userDir () {
  var folders = [process.env.HOME || process.env.USERPROFILE].concat(Array.prototype.slice.apply(arguments))
  var dir = path.join.apply(path, folders)
  mkdirp.sync(dir)
  return dir
}

function applyTextMarker (text, marker, size) {
  var availableSpace = size - vw.width(marker, true)

  text = vw.truncate(text, availableSpace, '...', true)

  return text + repeat(' ', availableSpace - vw.width(text, true)) + marker
}

module.exports = {
	  idFromName: idFromName
	, dirFromName: dirFromName
  , repeat: repeat
  , applyTextMarker: applyTextMarker
  , assertDir: assertFs.bind(null, 'dir')
  , assertFile: assertFs.bind(null, 'file')
  , userDir: userDir
}