var extend = require('extend')
var fs = require('fs')
var Handlebars = require('handlebars')

module.exports = plugin

function plugin (options) {
  options = extend({
    directory: 'helpers'
  }, options || {})

  return function (files, metalsmith, done) {
    fs.readdir(metalsmith.path(options.directory), function (err, files) {
      if (err) throw err

      files.forEach(function (file) {
        var templateName = file.split('.').shift()
        var path = metalsmith.path(options.directory, file)
        var helperContents = require(path)
        Handlebars.registerHelper(templateName, helperContents)
      })

      done()
    })
  }
}